Millennium Time Capsule/AC2000.BIN/disks/ac10disk/atozbook/s.txt

Text File | 1998-06-10 | 96KB | 2,335 lines

                             "The Atari A to Z"
                              by Mark S Baines
                      Copyright (c) 1998 Mark S Baines
                             All Rights Reserved


       YOU MUST READ "READ_ME.NOW" BEFORE YOU LOOK AT ANY OF THIS FILE
*****************************************************************************


S


Sampling
The process of measuring a variable (such as frequency) at timed intervals and
storing it to analyse or manipulate that data. Quite often, it applies to
converting the amplitude of an analogue waveform into a digital form, such as
with sound. This is synonymous with the term digitizing. The more often the
analogue signal is sampled, the more accurate the representation of the
resulting digital form will be. This is the sampling frequency, and if a
sample is taken 44,100 times a second then we have a sampling rate of 44.1 kHz
which is that used to produce audio compact discs. As long as the sample is
taken at a frequency greater than twice the highest frequency component of the
signal, then no data will be lost. Since the human ear cannot hear a frequency
above about 20 kHz, then the highest frequency sampled by a CD disc is 22.05
kHz which is quite adequate. The STE introduced hardware to playback sampled
sound from digital data stored in a disk file and loaded into memory. The DSP
system in the Falcon030 can sample sound through a stereo microphone input
with eight channels and 16-bit resolution. That means that sixteen bits are
used to store each sample of the analogue signal. Sampling rates are variable,
but typical ones are 49.17 kHz, 44.1 kHz (CD quality), 48.0 kHz (DAT quality)
and a maximum of 62.5 kHz. The Falcon can play back this digital sample at
these rates as well. See DMA sound, DSP, Falcon.


SASI
Shugart Associates System Interface. The precursor to SCSI developed by
Shugart in the 1970s as a hard disk controller.


SC1224
Atari 12 inch colour monitor with .38 mm dot pitch, RGB analog input, a
vertical scan rate of 60±10 Hz and horizontal frequency of 15.75 kHz. Maximum
resolution is 640 x 200 or 80 columns x 25 lines. It has a built-in speaker
and many external controls.


SC1435
Atari 14 inch colour monitor effectively replacing the SC1224. It has a swivel
base.


Scalar
Capable of being represented by a single number, as opposed to vectors which
are represented by two end coordinates.


Scalable font
A typeface font that is constructed from a set of mathematical rules
describing each character's appearance rather than using a bitmap. The
advantage is that any character can be scaled to any point size without loss
of detail or crude 'blockiness' that is the result of scaling bitmapped fonts.
A single scalable font file can therefore give rise to any set of font sizes
which saves enormous amounts of disk space as well as computer memory when
utilizing fonts, in a DTP program, for instance. Such fonts can also output to
any device so that there isn't the need for separate screen and different
printer fonts. It has to be noted that any output from a scalable font is
bitmapped when it appears on the screen of a computer or on paper when printed
as computer screens, laser printers and dot matrix printers are all bitmapped
devices. For very small point sizes, bitmapped fonts may be superior depending
on the algorithm used by the scaling routine for scalable fonts. Some scalable
fonts have a special algorithm for producing small point sizes to optimize the
positioning of the few dots making up a character at that size. This is known
a hinting. Scalable fonts are also called outline or vector fonts.


Scale
The size relationship between one entity or value and another. Also, to change
values to bring them within a certain range, for instance to make the
dimensions of a drawing smaller (reduce its scale).


Scan
In a CRT, to move the electron beam across the display area in closely spaced
lines in order to place an image on the screen. Also, to pass a sensor across
a graphic image in a sequence of closely spaced lines in order to detect
differences in light transmission or reflectivity and so to represent that
image as a series of electrical signals for transmission to a device for
storage and manipulation. Also, to continually read registers or other bit
positions in rotation for changes to them.


Scan line
A line followed by a scanning element, such as an electron beam across a CRT
screen or image.


Scanner
A device that passes a sensor over a graphic image in a sequence of parallel
lines in order to detect differences in light transmission or reflectivity
converting that image to a bit-pattern for storage, manipulation and
reproduction. The resulting file is a bitmap file, usually in the IMG format.
Also, a device that can connect a single circuit to each of a number of other
circuits in rotation, as in multiplexing.


SCC ports
These are two serial ports on the Mega STE, TT and Falcon using the Zilog
85C30 SCC chip. Port A can be used as the Local Area Network port or as a
high-speed RS-232C port the output being directed to the appropriate connector
(when bit 7 of the PSG sound chip Port A is zero, LAN mode is selected). Port
B is a high-speed RS-232C serial port for modems. Both the serial ports are 9-
pin DB connectors (joystick-like) compatible with IBM PC-AT style. Port B has
the Ring Indicator signal connected. The Port A LAN connector port is an 8-pin
female DIN connector. On the Falcon030 the SCC ports are the only serial
ports, (Port A always being the LAN port) whilst the TT has two MFP 68901
ports as well. The SCC can handle both asynchronous and synchronous transfers
with speeds up to 115,200 bps on Port A and 153,600 bps on Port B although
there is no provision within the XBIOS to support such a speed. See LAN port,
Zilog 85C30 SCC.


Scope
The parts of a program in which a variable can be accessed. In block
structured languages such as C and Pascal, it extends to the end of the block
in which it was declared, including any inner blocks.


Scrap file
A temporary work file often used to transfer data between applications as in
the Atari Clipboard protocol. The file is normally called SCRAP.* where the
extender specifies the type of data it contains.


Scratch
To erase data from a magnetizable surface medium.


Scratch file
A file allocated to a program as a temporary work file.


Screen
That part of a display device where the display appears.


Screen image
The display image.


Screen saver
If the monitor screen if left with an unchanging display for any length of
time (no-one appears to know exactly how long) the electron beam will burn the
image into the screen phosphors permanently. Subsequent use of the monitor
will reveal a faint ghost image of this display on top of the current one. To
stop this happening there are many programs available which come into effect
only after a certain amount of time of inaction from the mouse or keyboard.
Many of these will just blank the screen and will require some memory to store
the display image beforehand. On a monochrome screen, some will reverse video
the whole display image every few seconds. This does not require any memory
and acts as a warning to the user that he hasn't done any work for the last
five minutes! Others will present a constantly changing image to the screen
for amusement. Another method is to blank the screen and require the user to
enter a password to unblank the display. This may be useful in offices where
sensitive data is being used and a user does not wish to switch off the
computer when she leaves her desk.


Scroll
Where display elements make vertical or horizontal movements across a screen
under user control. As the display image disappears at one edge it is replaced
at the other thus maintaining a complete screen image. The use of the arrow
keys and/or GEM window scroll arrows and scroll bars are normally used for
scrolling.


Scroll arrow
Arrow icons on the right and bottom GEM window edges which move the display by
a single increment in the direction of the arrow. If the display is of text,
then the movement is normally one text line vertically and one character
horizontally. If it is a graphics display, say an image file, then the
movement will be some small prearranged size, for instance 8 or 16 bits.


Scroll bar
The right and bottom GEM window edges containing two scroll arrows, a scroll
box and one or two shaded areas each. They are joined together in the bottom
right-hand corner by the Size box.


Scroll box
The white scroll box (although it may be coloured to a user's choice in TOS 2,
3 and 4) within the scroll bar of a GEM window indicates the current position
of the window's contents relative to the whole file. The size of the scroll
box compared to the shaded areas next to it corresponds to the portion of the
total file currently in the window. The scroll box can be used for scrolling
the window, one window area unit in any direction by clicking in the shaded
area. Finer control can be had by dragging the scroll box along the scroll bar
to a required position.


SCSI
Small Computer Systems Interface. A common interface standard for linking up
to seven other devices to microcomputers originally developed by Shugart
Associates in the 1970s as a hard disk controller called SASI. It has a 50-pin
connector (two rows of 25) allowing for two-way communication, although the
SCSI port on the Mega STE and TT is a 25-way connector (the full 50-pin
cabling is used internally). Theoretically, any device with the appropriate
interface can be connected to a computer, such as disk drives (floppy, hard
disk, CD-ROM, removable SyQuest cartridges), tape devices, scanners,
typesetting machines etc. The SCSI port on the Mega STE and TT is controlled
by a NCR5380 SCSI controller which is capable of a data transfer rate of 4 Mb
a second with access to the full 32-bit address space on a TT. The most up-to-
date version is SCSI-2 which has a theoretical transfer rate of 40 Mb per
second. The Falcon's SCSI port complies to this standard and the ACSI is a
subset of its commands. Third party developers provide SCSI 2 to ACSI adapters
to allow the Atari SLM laser printers and Atari hard disks to be attached to
the Falcon's SCSI port.

  Table S1: SCSI Pin Functions

  Pin   Meaning/Function
   2    Data bit SCSI ID 0 - DB(0)
   4    Data bit SCSI ID 1 - DB(1)
   6    Data bit SCSI ID 2 - DB(2)
   8    Data bit SCSI ID 3 - DB(3)
  10    Data bit SCSI ID 4 - DB(4)
  12    Data bit SCSI ID 5 - DB(5)
  14    Data bit SCSI ID 6 - DB(6)
  16    Data bit SCSI ID 7 - DB(7)
  18    Data bit parity - DB(P)
  20    Ground - GND
  22    Ground - GND
  24    Ground - GND
  26    Terminator power
  28    Ground - GND
  30    Ground - GND
  32    Attention - ATN
  34    Ground - GND
  36    Busy - BSY
  38    Acknowledge - ACK
  40    Reset - RST
  42    Message - MSG
  44    Select - SEL
  46    Control/Data - C/D
  48    Request - REQ
  50    Input/Output - I/O

All odd numbered pins, except pin 25, are connected to ground (GND). Pin 25 is
not connected. Pin one is marked by a triangle indentation on the connector.
For the pinouts on the TT and Falcon see the Connectors Appendix C.


SCU
System Control Unit. A TT chip providing an additional level of interrupts
control for the system, containing registers that allow the software
generation of interrupts. There are two mask registers permitting independent
control over which levels will be seen by the processor. There are interrupt
request registers showing the current state of the seven interrupt request
levels from each of the sources and there are two read/write registers for
system configuration information. A system bus timer is also implemented where
the SCU will signal a bus error if nothing concludes a bus cycle within
sixteen microseconds.


SD
Single Density. An outmoded and unused form of data encoding using simple FM
techniques for disk drives.


SDMA
The Atari custom chip in the Falcon030 which is the SoundDMA coprocessor chip.
See DMA, DMA Sound.


Search
An operation performed to locate one or more particular items amongst a group
of such items.


SECAM
SEquential Couleur A Mémoire. The French television standard. See PAL and
NTSC.


Secondary channel
A data communications transmission channel that can be used as a supervisory
channel for low-speed data that is independent of the main channel.


Second generation computer
A computer employing transistors circa 1950s-early 1960s.


Sector
The smallest unit of any track on magnetic disk storage that can be accessed
directly by the hardware of the disk unit. Each track consists of several
sectors, the norm being nine on a double density floppy disk, forming 'pie-
slice' shaped divisions on the disk surface.


Security
The operations and checks made to prevent loss or corruption of data and to
prevent unauthorized use of programs and data.


Seek
The operation of moving the read/write heads on a magnetic disk unit to the
correct track position so as to read or write data.


Seek rate/time
The measurement of the time required to move a disk drive's read/write heads
to a different track. It is usually expressed as an average time, that is, the
time required to move to half the number of tracks on a disk surface.


Segment
A separately loadable sequence of instructions as part of an overlay program.
Also, one of the components of a LED or LCD display character.


Select
To chose one of several items or possibilities, such as an item from a menu.
Single-clicking on an item on the GEM Desktop will select that item which will
remain highlighted to show its selection.


Semantics
The study of the meanings of words, concerned with their definitions rather
than their use in relation to others (syntax). In programming, it is the
relationship between the use of symbols and keywords and their consistency of
meaning. For instance, it is a semantic rule that forbids reserved keywords,
such as FOR or which, to be used as names for variables or functions.


Semaphore
A flag, a bit or bit-group indicating that a particular event has occurred
during processing. In the concurrent processing of two interdependent
programs, it is a control structure by which intermediate results are passed
between programs.


Semiconductor
An electronic device that depends on a controlled, unidirectional flow of
electrons between two types of silicon or germanium for its operation, silicon
being the most commonly used. Pure silicon is a poor conductor of electricity
and so if 'doped' with a small amount of another substance, usually
phosphorus, free electrons become available to conduct electricity, this being
N-type (negative) silicon. If boron is used, for instance, 'holes' appear
between which electrons can jump, this being P-type (positive) silicon. If the
two types of silicon are placed side by side, a junction is formed and a
depletion layer forms where no carriers (electrons or holes) exist. If a
current is maintained, the depletion layer can grow and exist as a barrier to
further current. If the arrangement of N-type and P-type silicon is reversed
or the polarity of the current, then the depletion layer disappears. A
semiconductor device that limits current to one direction is called a diode.
All semiconductor devices use depletion layers to control current.


Semiconductor device
An electronic component consisting of one or more semiconductors and circuit
terminals for wiring into a circuit.


Semiconductor memory
Memory in which each storage cell consists of one or more semiconductors. ROMs
have a bit permanently written in each storage cell, whilst RAM has storage
cells which can be changed quickly by an electrical pulse. Semiconductor
memory is normally coordinate-addressable memory in which each storage cell is
arranged in a matrix with connecting 'row' and 'column' conductors by which
they are selected for reading and writing.


Send
To move signals or messages from one location to another.


Sense
To detect a particular physical condition or a change in one and to output an
electrical signal as a measurement of that condition or change.


Sensitive
Capable of detecting a small change in some condition.


Separator
A delimiter, a character that separates units of data in storage or
transmission.


Sequence
A group of items arranged in some particular order one following another.
Also, a set of procedural or programming steps taken one after another.


Sequencer
A program used in conjunction with MIDI devices that can be likened to a
multi-track tape recorder on which separate music parts can be recorded
building up, track by track, a more complex piece of music. A sequencer allows
for the editing, storage, manipulation and play back of this music data.


Sequential
Arranged or occurring in sequence.


Sequential access
An operating system access that presents records to an application in an order
according to the numeric values of their keys rather than the organization of
the records in the file.


Sequential file
A file in which records are held in physical locations in storage in an order
according to the numeric values of their keys.


Serial
In a string, following one another in space or time.


Serial access
An operating system access that presents records to an application in the
order in which they are held in storage.


Serial access device
A device where the access of a particular item requires the reading, checking
and counting of other data items first, such as in tape. Such a process is, of
course, slower than random access.


Serial file
A file in which records are stored one after another on the storage medium
without regard to the sequence of their keys.


Serial interface
An interface through which data can only pass in bit-serial form, such as the
RS-232C port. Although many other interfaces are bit-serial (MIDI, LAN, floppy
disk) the term normally refers to the modem or RS-232C port. See RS-232 port,
SCC ports, RS-232C.


Serial number
A number, usually unique and perhaps with letters, placed on an item by a
manufacturer to provide identification of that item. Serial numbers are
commonly found on software as well as hardware items, that number being the
unique registration or licence number of the software. Floppy disks also have
a serial number which is randomly chosen and written to the disk when it is
formatted. It is used by TOS which checks these numbers whenever a disk is
placed into the drive. If the operating system suspects that a disk has been
changed, it checks the serial number before writing to the disk assuming that
it is the same disk if the serial number matches. It is important, therefore,
that third party floppy disk formatters correctly provide random and unique
serial numbers for disks. Unfortunately some of the earlier ones and
preformatted disks do not which can cause the complete loss of a disk's data
when swapped undetected in a drive. A disk's FAT data is stored in a memory
buffer and if a file is copied onto the second disk the original disk's FAT is
also copied which, bearing no resemblance to the second disk's contents,
corrupts it.


Serial port bug
The most persistent bug in TOS is the notorious serial port bug. In fact, over
the years it has been a series of different bugs which Atari kept introducing
as they tried to deal with a much deeper underlying problem. TOS and the
actual hardware in all Atari computers is incapable of handling the CTS/RTS
hardware flow signals correctly. TOS 1.0 doesn't handle CTS at all and a patch
program called TURBOCTS corrected the bug but added overheads to the data
transmission, slowing it down. The bug was corrected in TOS 1.2 but another
bug was introduced with the Rsconf() function in TOS 1.4 which meant that flow
control cannot be turned on at all. Setting RTS/CTS resulted in no flow
control at all. This was fixed in TOS 1.6 and 1.62.

With the introduction of TOS 2 and 3 the serial port bug was reintroduced but
again cured in TOS 2.06 and 3.06 which supposedly do not need any patches.
However, further investigations of the root of the problem show that it is not
due to an incorrectly written TOS but due to the nature of the systems
hardware that goes back to the original design of the ST. It would appear that
the priority of the CTS interrupt in the MFP 68901 chip is too low at Level 2,
resulting in the computer's RS-232 buffer to still send data after the CTS
signal has been lowered. To fix this hardware problem is likely to make a lot
of software (not just comms and printer drivers) stop working. Atari took the
decision a long time ago not to do that but to try to alleviate the symptoms
as much as possible, hence the relevant patch programs from them and third
parties.


Serial processing
Processing in which each item in a sequence of instructions passes through the
processor one after another. See Parallel processing.


Serial transfer
A bit-serial transfer.


Serializer
A device that converts bit-parallel data to bit-serial form, such as a UART.


Series
A sequence, items or events occurring one after another. Also, a string, a
group of items arranged contiguously.


SERPTCH.PRG
An official freeware Atari patch program to fix the serial port RTS/CTS
problem in TOS 2.05, 3.01 and 3.05. It should run from the AUTO folder.

Besides having serial ports controlled by the usual MFP chip, the Mega STE and
TT also have serial ports supervised by a SCC chip. Unfortunately, additional
bugs were introduced into the SCC code concerning parity and word size. Also,
on the Mega STE the Iorec(0) function (which obtains information vital for any
comms program to work properly) does not work correctly. SERPTCH.PRG fixes
these problems as well.


Server
A central and controlling computer with large storage capability in a local
area network supplying applications and data to the stations. Also, in any
connection between two computers on the Internet, there are two pieces of
software communicating with each other - a client and a server. The client
runs on the computer requesting the service and the server runs on the remote
computer providing it. The network using TCP/IP is the medium by which the two
programs communicate.

Servers normally run in the background and are often referred to as 'daemons'.
When called they tell the networking software they are ready to receive
commands. Any results are sent back and then they wait for the next
connection. A communication protocol ensures that servers can handle a variety
of clients and operating systems. See Client.


Service provider
A company that provides access to the Internet for a fee, such as Demon
Internet Services, EasyNet or CIX. The connection is usually via SLIP or PPP
using a modem and telephone line.


Set
A group of items of the same class to be used in sequences or combinations to
perform some function, such as a character set. Also, to place a device in a
particular condition or establish a particular value or condition. Also, to
write a 1-bit in a particular location or to put into a form acceptable for
printing.


Set up
To make a functional unit or program ready for operation.


Setup
The arrangement of a system.


SF314
Atari external double-sided 3.5 inch floppy disk drive with an average access
time of 96 ms and data transfer rate of 250 Kbits/s.


SF354
Atari external single-sided 3.5 inch floppy disk drive with the same
specifications as the SF134 but with only one head.


SFP004
An Atari expansion board for the internal expansion bus of the Mega ST
computer which contains a MC68881 floating point processor and the logic
devices to decode addresses. The MC68881 appears as a peripheral input/output
port in the memory map of the Mega ST as the MC68000 CPU does not support
coprocessors unlike the MC68030. This makes the operation of the MC68881
slower, but processing is still faster than if one wasn't fitted. Using
floating point routine benchmarks, the SFP004 can improve certain operations
by a factor of ten. Programs specifically written for the SFP004 will not
recognize a MC68882 on a TT and will not work, but 'will' work on a Mega STE.
See FPU, MC68881, MC68882.


SH204
First Atari external 20 Mb 5.25 inch hard disk drive in a 'brick-like' case.
Using MFM encoding with 2,448 tracks, 612 cylinders and 17 sectors per track.
It has a data transfer rate of 5 Mbits/s.


SH205
Atari external 20 Mb 5.25 inch hard disk drive in a Mega ST type case.


Shareware
Shareware programs are commercial programs and not to be confused with public
domain or freeware programs which carry no charge. The programmer retains
copyright as with freeware programs but normally allows the user to run the
program for a specified amount of time or under other conditions specified in
the documentation. After those conditions are met or that time period it up,
the user is under a legal obligation to pay the shareware fee for the program.
If the user doesn't then he must delete the program as he will be unauthorized
to use it. Shareware programs are usually cheaper than commercial programs and
use this 'try before you buy' distribution method, where they are available
form PD libraries and bulletin board networks. Because they are freely
available does not affect their commercial nature and the legal rights and
obligations of the programmer and user. Although the concept of shareware is
very successful in the US, it has not seriously caught on in the UK where the
majority of users do not pay the required fees. A common excuse is the
perceived difficulty in sending money abroad which is, in fact, very easy
through any Post Office or Bank. See Public domain, Freeware.


Sheet feed
A term applied to a printer that uses separate sheets of paper rather than
continuous stationery.


Shell
A user interface program from which other programs can be run and returned to
after completion, such as a menu system or GUI.


Shift
To move bits one bit increment at a time to the left or right. In text
processing, it may be one character increments (eight bits), such as when
characters are inserted into a line of text. Also, in a keyboard, to change
the relationship between the keys and the characters they cause to be printed,
such as the [Shift] key which changes characters between upper and lower case
or provides extra punctuation marks. Also, to change a value or position as in
a frequency change in frequency shift keying.


Shift-click
Clicking with the mouse button whilst holding down the [Shift] key.


SHIFTER
An Atari custom chip converting the data in video RAM into a monitor signal
output from the monitor or TV modulator port. On the ST it is a 40-pin DIL
packaged chip and takes its data in 16-bit parallel form from RAM with the MMU
handling the addressing. The data sent to the monitor or modulator (if fitted)
is in bit-serial form. The GLUE chip provides the VSYNC and HSYNC signals for
synchronizing the monitor to the video output, the DE (Display Enable) and
BLANK signals. The SHIFTER can produce a monochrome output signal and three
sets of colour signals, red, green and blue. The SHIFTER also produces a 16
MHz clock signal from the master crystal's 32 MHz signal. On the STE and TT
the SHIFTER was converted to allow for the greater colour palettes. It exists
as an 84-pin PLCC chip and is normally socketed. Besides the red, green and
blue colour signals, it also produces the HSYNC, VSYNC and DE signals. A
separate SHIFTER, a National DP8516 graphics processor is used on the TT to
generated the TT high resolution mono display. See RGB, TTVIDEO, DP8516.


Shift key
A keyboard key that is used to change the characters produced by other keys,
such as from lower case to upper case letters or to provide a '£' character on
the [3] key.


SHIPACC.PRG
An official freeware Atari program that 'ships' hard disks, that is, parks the
heads of the hard disk. As most disks are auto-parking, this program is not
generally required.


Short, shortword
A 16-bit integer on the ST-Falcon range.


SI
Système International d'Unités. The international metric system standard.


Sign
A symbol or character(s) associated with a number to indicate whether it is
positive or negative, such as the - and + signs.


Sign bit
The most significant bit in a bit-pattern indicating the sign of the bit-
pattern's value of a signed number. Conventionally, a 0-bit indicates a
positive value and a 1-bit a negative value. See Signed number.


Signal
A particular line condition, or change of it that is passed between two
locations to represent data or control sequences. The line condition is either
a carrier wave frequency or a voltage. Also, a message from one process to
another in a multitasking environment. See MiNT signals.


Signed number
A number with a sign associated with it, such as -45 or 378 which is assumed
to imply +378. A signed 16-bit integer will have a range of -2^15 to +2^15 (-
32,768 to 32,768), the positive value being half that of an unsigned integer
which has the range 0 to 2^16 (65,536), because of the loss of one bit as the
sign bit.


Significant digits
Those digits with the highest positional values or weights in a number, at the
left, are the most significant digits. Those on the right are the least
significant digits. See MSD, LSD.


SIL
Single In-Line. An integrated circuit chip package with a single line of pins
in line.


Silicon - Si
An abundant element which is the main constituent of glass and the wafers made
to form semiconductors.


Silicon Valley
A term applied to the area around Palo Alto and Sunnyvale south of San
Francisco where there is extensive semiconductor development and
manufacturing, as well as the home of some of the leading computer companies
and research institutions.


SIMM
Single In-line Memory Module. A compact memory expansion board containing
eight or nine DRAM chips which plugs into an appropriate carrier on a
computer's motherboard via a single row of connection pads on its lower
surface. They are used extensively in PCs, providing a cheap and easy user-
installable means of upgrading memory. Some STEs have SIMM sockets depending
on their price at manufacture of the motherboard.


Simplex
The transmission of data in only one preassigned direction.


Simulation
The use of a computer and programs to form an analogue model of some system so
that it can be tested with different inputs and under different conditions.
Research on simulation models is cheaper than on the 'real' thing, which may
have to be built many times before it is correct. Some models may be of
systems that can't directly be perceived by the human senses, such as inside a
molecule, on another planet or the world's weather system.


Simultaneous
Also, parallel or synchronous. Occurring at the same time or during the same
time interval.


Single precision
The use of a single word to hold a numeric value.


Single-stepping
An operation in which instructions are translated one at a time, executed and
the result displayed, such as in an interpreter or debugging monitor program.


SIP
Single In-line Package. A compact memory expansion board containing eight or
nine DRAM chips which plugs into an appropriate carrier on a computer's
motherboard via a single row of connection pins on its lower surface. They are
used in PCs although less frequently than SIMMs, providing a cheap and easy
user-installable means of upgrading memory. Some STEs have SIP sockets
depending on their price at manufacture of the motherboard.


Size box
The bottom right-hand corner GEM window icon that changes the size of the
window by dragging the icon and the window outline on the screen.


Sizing
The process of changing the size or shape of an active window.


Skewing
See Interleave.


Slave
A device that cannot initiate its own actions thus being under the control of
another.


Slider
A mouse controlled GUI graphic device representing sliding controls to alter
particular values, as in the Control Panel accessory. They work in the same
way as the scroll bar of a window.


SLIP
Serial Line Internet Protocol. An ad hoc protocol that allows a computer to
connect to the Internet and use the Internet Protocols (IP) using a modem and
standard telephone line. Such connections are usually for stand-alone
(unnetworked) PCs and made through a Service Provider. Although SLIP
connections are better for bulk transfers via ftp it is rapidly being
superseded with PPP ones. See TCP/IP, PPP.


SLSI
Super Large Scale Integration. An integrated circuit with more than 100,000
logic gates per chip.


SLM605
Atari dumb laser printer superseding the SLM804. It has a smaller footprint
than the SLM804 and a more modern and sleeker appearance. It is rated at six
pages per minute and supports letter, legal, A4 and B5 paper formats. It has a
resolution of 300 x 300 dpi.


SLM804
The first Atari dumb laser printer.


SSI
Small Scale Integration. An integrated circuit with less than ten gates per
chip.


SSI
Synchronous Serial Interface. Another name for the Falcon030 external DSP
port.


SM124
The first Atari 12 inch non-glare, white phosphor monochrome monitor for the
ST range characterized by its sharp and stable image with a high scan rate of
71.4 Hz, a horizontal frequency of 35.7 kHz and low electromagnetic radiation.
It is capable of a resolution of 640 x 400 pixels but with an overscan
modification a newer version can display up to 704 x 480 pixels. An internal
mono speaker was supplied.


SM125
The Atari 12 inch 640 x 400 pixel monochrome monitor with swivel base,
external picture controls and a mono speaker. It replaced the SM124 for a
time, but some production difficulties caused Atari to revert to the older
design.


SM144
Atari 14 inch 640 x 400 pixel monochrome monitor, initially of poor
manufacture causing many to be returned and for it to be replaced by the SM146
and SM147. It has a flatter screen than the SM124/5 and a mono speaker.


SM146
Atari 14 inch monochrome monitor replacing the SM144.


SM147
Atari 14 inch monochrome monitor replacing the SM144.


SM194
Atari 19 inch monochrome monitor for the TT with up to 1,280 x 960 resolution.
Now known as the TTM194.


SM195
Atari 19 inch monochrome monitor for the TT with up to 1,280 x 960 resolution.
Now known as the TTM195.


Small scale integration - SSI
An integrated circuit with less than ten logic gates.


Smart
Intelligent, with programmable memory.


SMD
Surface Mount Device.


SMM804
An early Atari 9-pin dot matrix printer.


Smiley
A group of ASCII characters in e-mail and other messages that represent a
simple image which, in turn, denotes a particular emotion which the writer
wishes to convey in his message. They are viewed by turning the head to the
left and work best with monospaced characters. The basic smileys are:

  :-)   Happy
  ;-)   Winking, mischievous
  :-(   Sad
  :-|   Frown

The main reason for their use is to overcome the lack of body language and
expression in e-mail which are normally present in face-to-face conversations
and hence reduce misunderstanding. There are many hundreds of these, most very
obscure.


SMT
Surface Mount Technology.


SMTP
Simple Mail Transfer Protocol. Part of the TCP/IP protocols which describes
the format of an e-mail message and how mail programs should handle them. See
TCP/IP, E-mail.


Snapshot
A program performing a dump of designated locations during the execution of a
program, such as of processor registers and other memory locations for
debugging. The term is, however, commonly associated with any program that
saves the screen image to a file (rather than sending it to the printer). The
normal file format is either GEM IMG or one of the Degas formats depending on
resolution. Such screen dumps can be inserted into documents within a DTP
program, for instance.


SNDSHIFTER
An Atari custom chip for the STE and TT controlling the 8-bit stereo digital
sound replay timing.


Socket
A female connector.


Soft copy
Data that is displayed on a screen rather than paper (hard copy).


Soft keys
Keyboard keys that are user programmable.


Software
Any bit-patterns stored and manipulated by a computer. The term contrasts with
'hardware' and although it encompasses data, the term is often used to imply
programs only.


Software development
The development of programs for a particular application.


Software engineering
Software development.


Solid state
A device or circuit that uses semiconductors rather than relays and valves.


Son
A term applied to the current version of a file. See Generation.


Sort
To arrange entities according to some predefined criteria into groups or
sequences.


Sort key
A value that, if present in an item, results in it being sorted into a
particular group.


Sound
The sound capabilities of the ST was rather crude when released, using the
same family of sound chip (PSG) as the 8-bit micros, the AY-3-8910 or YM-2149.
The sound system on the STE was enhanced using a full PCM stereo output with
DMA support and a National LMC1992 Volume/Tone Control chip. Output is stereo
to two phono sockets and can be mixed with the PSG sound at these sockets or
sent to the mono monitor loudspeaker. This sound system is carried over into
the Mega STE and TT. The Falcon030 introduced another sound system whilst
still retaining the other two for compatibility. Here, eight channel 16-bit
digital DMA sound is supported with stereo 16-bit digital input and output
with up to a 50 kHz sampling rate. A SoundDMA, CODEC (DAC and ADC) and a
Digital Signal Processor are used to make processing of this sound data very
quick and versatile. See YM-2149, DMA sound, DSP, LMC1992, PCM.


Sound chip
An integrated circuit capable of generating synthesized or sampled sounds. On
the ST range it is the Yamaha YM-2149 chip.


SoundDMA
See SDMA.


Source
An original or input form document. Also, a place from which data is read or a
data transmission originates. In source code or consisting of source code.


Source code
A form of a program as produced by a programmer in a programming language
before it is compiled or interpreted. The file is normally a straight ASCII
text file and produced in an editor and does not constitute a program until it
is translated.


Source disk
The disk that data is written from during a copy or diskcopy operation.


Source file
A file containing a program or routines in source or programming language
form.


Source language
A programming language.


Space
A storage location of the correct size for a particular unit. Also, ASCII
character 32, the character acting as a word delimiter in text appearing as a
blank or gap between characters. Also, synonymous with a 0-bit in data
transfer.


Spacing
The typographical control of space between letters and words.


Span
The difference between the highest and lowest values of a quantity.


Sparrow
An Atari TOS compatible computer which had similar specifications to the
Falcon030. The original Falcon was a high-end machine probably a successor to
the TT with a 32 MHz 68040 processor and 24-bit true-colour. Its development
was slow and finally dropped by June 1992 when Atari started calling the
Sparrow the Falcon030.


Sparse
With gaps or omissions, without all places being filled.


Sparse array
An array with a size greater than initially required.


Special character
Any character other than letters, numbers, and a space, i.e. !"£$%^&*() etc.


Specification
A description of the design features and functions of an item, such as
hardware or a program.


SPECmark
Systems Performance Evaluation Cooperative's benchMARK. A SPECmark is an
average performance of a computer carrying out a set of ten benchmarks as set
by the participants of SPEC. A MC68040 has a SPECmark of eleven compared to an
Intel 80486 of 19.


Speech chip
An integrated circuit that holds speech in a digitized form and can be used to
reproduce it, usually and unfortunately with a Californian accent!


SpeedoGDOS
A new version of GDOS using the Bitstream Speedo Font Scaler technology which
replaced FSMGDOS as the Atari font scaling module. Readily available Bitstream
fonts can be used which are fully compatible with the new GDOS. Bitstream is
one of the largest font publishers with a huge library of fonts at reasonable
prices. SpeedoGDOS is reputedly faster than Adobe Type Manager on the Mac.

Development was passed to COMPO in 1994 and with the release of version 5
SpeedoGDOS now supports TrueType and PostScript Type 1 scalable fonts in
addition to Bitstream Speedo fonts. See FSMGDOS.


Spool
Simultaneous Peripheral Operation On-Line. To use an intermediate storage when
making a data transfer between high-speed storage and a slow device. Also, to
redirect the normal output of data to another destination, i.e. from the
screen to the printer or a disk file often with the intention of letting the
processor get on with another task whilst that data is printed in the
background.


Spreadsheet
A program using a large grid or worksheet of 'boxes' or cells arranged in
columns and lines into which data can be placed in the form of numbers,
formulae, text, commands etc. Columns, rows or blocks of data can be processed
by formulae entered by the user, which in turn may be processed in graphical
form, such as bar charts or line graphs. Most spreadsheets provide very
powerful functions to aid financial and scientific analysis of numerical data
to the extent that they effectively replace such things as ledger and accounts
books. The orderly array of data is also useful for simple databases and time
management projects. Spreadsheets are one of the three most used programs in
the world together with word processors and databases.


Sprite
A graphic block which can be moved around the screen without affecting what is
underneath it. They are usually found in video games and controlled by
specifically written hardware. The GEM mouse pointer is a sprite.


Sprocket feed
A printer mechanism that moves continuous paper by means of a sprocket or
tractor with pins that engage holes at the edges of the paper.


Spurious interrupt
A processor exception that results when a bus error occurs during a system
interrupt and causing 24 bombs. See Exceptions vectors, Bombs.


SQL
Structured Query Language. A language used with databases and defined by ANSI
to make queries of data and to format the results into a report or file which
is portable to other systems or programs.


SRAM
Static Random Access Memory. See Static RAM.


SS
Single-Sided. A disk which has only one usable surface for data storage.


SSI
Small Scale Integration.


SSI
Synchronous Serial Interface. Another name for the Falcon's external DSP port.


ST
Sixteen-Thirtytwo. The ST's name is derived from the architecture of the
MC68000 chip which has 16-bit external and 32-bit internal addressing. The ST
came in various forms as it evolved but essentially featured an 8 MHz 68000
with 512 K of RAM although some very early models only had 256 K RAM. The TOS
was loaded from disk originally, which was probably the initial impetus for
the increase in memory, and a mouse and GEM interface was standard. TOS was
incorporated into a 192 K ROM soon after. The single-sided 360 K floppy disk
drive was a separate unit (SF354) which was incorporated into the body of the
machine with the introduction of the STF. Although the 68000 CPU has the
capability to address memory up to 16 Mb, the MMU has always reduced that to a
maximum of 4 Mb. Screen resolutions of 320 x 200 x sixteen colours, 640 x 200
x four colours and 640 x 400 in monochrome were excellent when launched but
the lower resolutions have become quickly dated. The wide range of ports,
parallel, serial, MIDI, DMA (hard disks) floppy drive, joystick, mouse and
video helped to make the initial machine attractive and versatile. The
inspired inclusion of MIDI ports guaranteed its use in the MIDI and electronic
music revolution that developed in the late 1980s making a strong niche for
the ST which remains today.

  Table S2: ST Specification

  Processor          8 MHz MC68000
                     DMA
  Bus                16-bit external data, 32-bit internal data, 24-bit
                     address
  RAM                512 K or 1 Mb
  ROM                6 sockets providing 192 K of ROM space
  Floppy Disk Drive  3.5" single-sided double density 360 K replaced by
                     double-sided 720 K. Internal on 'F' designated STs or
                     external SF354 or SF314
  Input/Output       MIDI in and out (5-pin DINs)
                     Monitor port (13-pin DIN) for ST monochrome or colour
                     monitors
                     RF modulator output on 'M' designated STs (colour
                     resolutions only)
                     Parallel printer port
                     Serial port from MFP 68901 (25-pin DB)
                     External floppy disk (14-pin DIN)
                     Atari ACSI connector with DMA (19-pin DB)
                     ST compatible cartridge port (128 K)
                     ST joystick port (9-pin DB)
                     ST mouse port (9-pin DB)
  Video              Colour palette of 512 colours:
                     320 x 200 x 16 colours ST low resolution
                     640 x 200 x 4 colours ST medium resolution
                     640 x 400 monochrome ST high resolution
                     Text display 80 columns (high resolution) or 40 columns
                     (low resolution) x 25 lines
  Sound              3 channel PSG sound
                     Total MIDI compatibility
  Keyboard           Integral QWERTY keyboard, 95 keys, numeric keypad, 10
                     function keys, cursor keys
  Mouse              128 dpi 2 button
  Power              Originally external PSU. Internal on 'F' designated STs
  Operating System   TOS 1.0 with GEM Desktop in ROM (upgradeable to TOS 1.4)


Stable
Capable of maintaining an operating condition without change, fluctuations or
errors.


Stacy
Atari ST laptop, initially battery powered but later mains only and about the
size of a briefcase. It has an internal hard disk drive, floppy and backlit
LCD screen which is ST high resolution compatible. An external monitor can be
attached. A small integral trackball is used instead of a mouse to move and
control the cursor (a mouse can be plugged in) and the function keys, cursor
keys and numeric keypad are all half-sized keys to fit within the smaller
footprint. At 6.9 kg (15.2 lb) it was heavy and generally considered expensive
at around £1,500 but it was very popular with musicians who apparently cried
out for the machine despite its faults. A major problem was that a hard disk
equipped Stacy failed to run for more than an hour with its twelve C-size
batteries and around half an hour with rechargeable batteries. In the summer
of 1991, the battery pack was removed and the compartment sealed up with Atari
ceasing to claim that the Stacy was truly portable. A major redesign of the
motherboard to cater for CMOS technology and low-power drives to attain three
to four hours was in hand in 1991 but the ST Book reached a stage in 1992
where it replaced the Stacy's technology. A mains only version was still
available for some time if requested directly from Atari.

  Table S3: Stacy Specification

  Processor          8 MHz MC68000 (CMOS)
                     DMA
  Bus                16-bit external data, 32-bit internal data, 24-bit
                     address
  RAM                1, 2 or 4 Mb and 32 K static screen RAM
  ROM                2 sockets providing 256 K of ROM space
  Floppy Disk Drive  3.5" double density double-sided 720 K
  Hard Disk Drive    20 Mb or 40 Mb built-in
  Screen             Supertwist backlit LCD high resolution monochrome 640 x
                     400 built-in compatible with ST high resolution mode
  Input/Output       MIDI in and out (5-pin DINs)
                     Monitor port (13-pin DIN) for ST monochrome or colour
                     monitors
                     Parallel printer port
                     Serial port from MFP 68901 (25-pin DB)
                     External floppy disk (14-pin DIN)
                     Atari ACSI connector with DMA (19-pin DB)
                     ST compatible cartridge port (128 K)
                     ST joystick port (9-pin DB)
                     ST mouse port (9-pin DB)
                     Internal bus expansion port (64-pin)
  Video              640 x 400 monochrome ST high resolution
                     With external monitors -
                     Colour palette of 512 colours
                     320 x 200 x 16 colours ST low resolution
                     640 x 200 x 4 colours ST medium resolution
                     Text display 80 columns (high resolution) or 40 columns
                     (low resolution) x 25 lines
  Sound              3 channel PSG sound (ST compatible)
                     Total MIDI compatibility
  Keyboard           Integral QWERTY keyboard, 95 keys, half-size numeric
                     keypad, 10 half-size function keys, half-size cursor
                     keys, trackball
  Mouse              128 dpi 2 button
  Real-Time Clock    Battery backed
  Power              External PSU (originally battery powered)
  Operating System   TOS 1.4 with GEM Desktop in ROM


Stack
A data structure in which data items can be added or removed at one end only.
Stacks are closely associated with processors to provide a storage space for
holding the operands of an operation or the return addresses from routines.
See Push, Pop, LIFO.


Stack pointer - SP
The address of the location of a stack. The MC68000 in the ST and STE has two
32-bit wide Stack Pointers, one the System Stack Pointer (SSP) for its
Supervisor mode and the other the User Stack Pointer (USP) for User mode.


Stand-alone
Capable of functioning independently not requiring the support of other
systems or devices.


Standard form
Normalized form. See Normalization.


Standby
Where a functional unit is ready to operate and awaiting inputs. Also, a
system that is available to perform some function in the event of a failure of
another system or device. Also, a low-voltage condition used with static RAM
to reduce power consumption when not being read or written to.


Star network
A data network in which the remote stations are connected radially to the
master station or server. Each has an individual circuit thus enabling the
whole network to perform if one station goes down. However, communication from
one station to another is slow and places extra demands on the central, master
station.


Start bit
A 0-bit (usually) indicating the start of a character byte in an asynchronous
data transmission.


Start-stop transmission
Data transmission where a character is preceded by a start element (commonly a
0-bit) and followed by a stop element (commonly one or two 1-bits). Continuous
1-bits are sent when no character is being sent and the appearance of a 0-bit
indicates to a receiving station that a character follows. This station's
equipment is programmed as to the length of each character (seven or eight
bits usually) and uses this to separate these characters bits from the
'framing' bits. Start-stop transmission are normally asynchronous.


Start up
To place a device into an operational state. A cold or a warm boot of a
computer.


Statement
In a high-level language, a complete instruction.


Static
Not occurring or performed during the time a program is being executed. Also,
interference on a communications channel.


Static allocation
The allocation of processing resources, such as memory and devices, to a
program when initially run rather than during execution. See Dynamic
allocation.


Static memory
See Static RAM.


Static RAM
Static Random Access Memory. Very fast, volatile RAM in which each bit is held
in four or more transistor flip-flops needing no refreshing. However, the
resulting circuit is more complex than that of DRAM which only needs one
capacitor per memory bit and so less data can be stored in the same amount of
space. SRAM chips are more expensive than dynamic RAM but very much faster.
See DRAM, Wait states.


Static variable
A variable that is allocated storage space at run time and remains active
throughout execution, thus retaining its value.


Station
A user terminal or computer attached to a network.


Status
The condition that a device or operation is in at a particular time.


ST Book
Atari A4-size notebook computer weighing about 1.9 kg (4.2 lb). Based on an 8
MHz MC68HC000 ST running TOS 2.06 in a 512 K ROM, with a BLiTTER and a built-
in 640 x 400 mono LCD screen. It can be run for five to ten hours on seven AA
batteries with an optional rechargeable NiCad battery pack. Storage is 1 or 4
Mb of RAM and an internal 20 Mb hard disk drive. A separate small 3.5 inch
1.44 Mb floppy disk drive was to be an optional extra as well as larger hard
disks, FAX modems, external keyboard and a mouse. An expansion bus to the
MC68HC000 is fitted in place of the cartridge port. Built-in software included
a diary, calendar, alarm, calculator and a scheduler. File transfer software
utilizing the parallel port is also included which is vital without a built-in
floppy disk. Either the external disk drive is necessary or the ST Book can be
connected to another ST back at home or work. With PC compatible disks, it is
even possible to transfer ST software into a PC and port it across using a
serial connection and comms terminal software. One innovation is the
VectorPad. This consists of a pressure sensitive circular pad which is pressed
in the direction that the mouse cursor is to move, the greater the pressure
the faster the movement. Two extra pads act as mouse buttons. Apparently, in
practice some found it difficult to use. There were several other problems in
the design which caused its withdrawal from release in 1992 for a redesign.
The LCD screen (unlike the Stacy) did not have backlighting making it useless
in poor lighting situations and the cartridge port was absent making it
difficult for musicians (many of the perceived buyers) to use because of the
cartridge port dongles that most MIDI software use. A 120-pin expansion bus to
40-pin ROM cartridge connector was available but apparently presented
problems. The ST Book has a 'Suspend and Resume' feature whereby it can be
turned off in the middle of an application without loss of data. Features such
as this, its long battery life, its lightness and portability and excellent
screen and operating system place it well on a par with comparable PC note
books. With backlighting, a cartridge port, a faster processor and 4 Mb RAM
(and the right price!) this would have been an excellent computer and a great
advance on the Stacy.

  Table S4: ST Book Specification

  Processor          8 MHz MC68000
                     8 MHz BLiTTER
                     DMA
  Bus                16-bit external data, 32-bit internal data, 24-bit
                     address
  RAM                1 Mb low power pseudo-static. Upgradeable to 4 Mb
  ROM                4 socketed 1 Mbit ROMs providing 512 K of ROM space
  Floppy Disk Drive  Optional external battery powered 3.5" double density
                     double-sided 720 K
  Hard Disk Drive    20 Mb built-in
  Screen             Supertwist Nematic LCD high resolution monochrome 640 x
                     400 built-in compatible with ST high resolution mode
  Input/Output       MIDI in and out (5-pin DINs)
                     Parallel printer port
                     Serial port from MFP 68901 (25-pin DB)
                     External floppy disk (14-pin DIN)
                     Atari ACSI connector with DMA (19-pin DB)
                     Expansion bus port (120-pin)
                     ST mouse port (9-pin DB)
                     External keyboard connector
  Video              640 x 400 monochrome ST high resolution
                     Text display 80 columns (high resolution) or 40 columns
                     (low resolution) x 25 lines
  Sound              3 channel PSG sound (ST compatible)
                     Total MIDI compatibility
  Keyboard           Integral QWERTY keyboard, 84 keys, VectorPad mouse cursor
                     control
  Mouse              Optional
  Real-Time Clock    Battery backed
  Power              7 alkaline AA battery pack with optional AC adaptor with
                     rechargeable NiCad battery pack
  Operating System   TOS 2.06 with GEM Desktop in ROM
  Options            3.5" battery powered floppy disk drive
                     Internal FAXmodem, 2400 bps data, 9600 bps FAX,
                     MIDI/SMPTE adaptor


STE
Sixteen-Thirtytwo Enhanced. A development of the ST with 8-bit PCM stereo DMA
sound capabilities with variable playback frequencies and an enhanced colour
palette of 4,096 colours compared to the ST's 512 (only sixteen colours can be
shown on screen at once). PCM stereo sound is in addition to the normal
programmable sound generator. Hardware support for horizontal and vertical
scrolling, external Genlock support and analogue joystick, light-gun and
paddle controller ports are included. A major improvement over previous
designs was the inclusion of SIMM or SIP sockets for memory expansion, using
cheap SIMMs or SIPs used on PCs. However, Atari would not standardize on the
use of these sockets, using whatever was cheapest at the time of manufacture.
The TOS supplied is TOS 1.6 and 1.62. The Cookie Jar was introduced with this
version of the ST and the MICROWIRE bus interface. See DMA sound, PCM,
Hardware scrolling, Genlock, MICROWIRE.

  Table S5: STE Specification

  Processor          8 MHz MC68000
                     DMA
                     8 MHz BLiTTER
  Bus                16-bit external data, 32-bit internal data, 24-bit
                     address
  RAM                512 K or 1 Mb expandable to 4 Mb with SIMMs
  ROM                2 sockets providing 256 K of ROM space
  Floppy Disk Drive  3.5" double-sided double density 720 K
  Input/Output       MIDI in and out (5-pin DINs)
                     Monitor port (13-pin DIN) for ST monochrome or colour
                     monitors
                     RF modulator output for TV (colour resolutions only)
                     Parallel printer port
                     Serial port from MFP 68901 (25-pin DB)
                     External floppy disk (14-pin DIN)
                     Atari ACSI connector with DMA (19-pin DB)
                     ST compatible cartridge port (128 K)
                     ST joystick port (9-pin DB)
                     ST mouse port (9-pin DB)
                     2 enhanced joystick ports for analogue joysticks, light
                     guns and paddles (15-pin DB)
                     2 stereo sound output RCA-style phono sockets
  Video              Colour palette of 4,096 colours
                     320 x 200 x 16 colours ST low resolution
                     640 x 200 x 4 colours ST medium resolution
                     640 x 400 monochrome ST high resolution
                     Text display 80 columns (high resolution) or 40 columns
                     (low resolution) x 25 lines
                     Hardware assisted scrolling
                     External Genlock support
  Sound              8-bit stereo PCM DMA sound
                     3 channel PSG sound
                     Total MIDI compatibility
  Keyboard           Integral QWERTY keyboard, 95 keys, numeric keypad, 10
                     function keys, cursor keys
  Real-Time Clock    Battery backed
  Mouse              128 dpi 2 button
  Power              Internal PSU
  Operating System   TOS 1.6 and 1.62 with GEM Desktop in ROM


STE_FIX.PRG
TOS 1.6 contains a bug in the Desktop code that prevents the user from booting
into medium resolution. Examination of the DESKTOP.INF file will show a line
that starts with #E. The last number on this line is the resolution number and
always shows 3 instead of 2 for medium resolution. This simple patch which is
placed in the AUTO folder cures this problem. This bug is fixed in TOS 1.62.
The _INF Cookie shows that the TOS 1.06 Desktop medium resolution bug patch is
installed.


STF
Early model Atari ST with built-in single-sided (later double-sided) floppy
disk drive and power supply unit.


STFM
Early model Atari ST with built-in floppy disk drive (initially single-sided)
and RF modulator for connection to TV sets for colour resolutions only.


STM
Early model Atari ST with built-in RF modulator for connection to TV sets but
separate floppy disk drive and power supply unit.


Stop bit
A 1-bit used as a character delimiter in asynchronous start-stop transmission.


Storage
A device or medium that can receive, retain and output bit-patterns
representing data. Data is either read from or written to storage usually by
means of making a physical change in the medium, such as by using an
electrical pulse in RAM or magnetic field in disks. Data is stored in either
of two physical conditions representing a 0-bit or a 1-bit.


Storage allocation
The allocation of storage locations, usually memory, to executing programs
which is normally an operating system task.


Storage capacity
The amount of data that a unit of storage can hold, normally measured in
bytes.


Storage cell
The amount of storage medium that can hold one bit. The term normally applies
to a transistor flip-flop in semiconductor storage, such as RAM, but can apply
to the smallest unit of magnetizable disk track.


Storage code
The code in which data in a character form is stored, usually ASCII or EBCDIC.


Storage device
A functional unit that is capable of receiving, retaining and outputting data.
The term applies to any semiconductor memory as well as peripheral devices,
such as hard disks and tape drives.


Storage location
An addressable position where data can be held.


Storage medium
Computer storage as identified by its physical form - semiconductor, disk,
tape - rather than the device that operates the medium.


Storage protection
The procedures used to prevent corruption, loss and unauthorized access to
data. As an operating system function, it is concerned with preventing
executing programs from accessing locations other than those that they are
intended to access. See Memory protection.


Store
To place data into storage.


ST Pad
The early name for the Atari Stylus computer. See Stylus.


ST RAM
This is dual purpose RAM used for both video and system memory on a ST and TT
but only referred to as such on the latter. It consists of 120 ns or less DRAM
chips yielding a 64-bit wide internal bus for fast video access. The video
chip on a TT can only display screen data from ST RAM. The memory access
cycles are interleaved between the processor and the video controller in 250
ns RAM time slices allowing the video display memory to reside as part of the
main memory. During active display cycles the processor cannot access the
memory but is allocated the next 250 ns time slice. It interfaces to this RAM
through a 32-bit bus, but the video subsystem access memory on a 64-bit wide
bus, the TT SHIFTER having on-chip buffering to provide high bandwidths for
data. The DMA sound chip can only play data stored in ST RAM. See FUNNEL, Fast
RAM.


Stream
A continuous flow of bit-patterns between two points in a computer or data
transmission circuit.


Streamer
A high-speed magnetic tape unit normally used to backup a hard disk unit.


String
A sequence or series of items (usually characters) in contiguous positions.


String handling
The operations involved with forming and manipulating strings of characters,
such as counting, sorting, concatenating and appending.


Strobe
Pulses applied in a high-speed sequence to a group of contiguous locations.


Structure
The way elements are organized or arranged. A data structure is a group of
data items (which may be similar or of different types) arranged in a way to
aid access to them.


Structured program
A program produced by structured programming techniques. Usually, it has a
hierarchy of modules each with a single entry and exit point and through which
control passes in a downward sequence without unconditional branches to higher
levels of the structure.


Structured programming
A programming method intended to provide efficient, logical and non-
individualistic programs with economy of effort and ease of maintenance. It is
particular suited to large complex applications where these techniques force
attention on to the logical analysis and breakdown of the problem rather than
on trial and error and individualistic techniques. Each program consists of
modules of code representing the individual elements of the problem.


STTL
Schottky Transistor Transistor Logic. A development of TTL chips with faster
operation and using less power, which themselves form the basis of a whole
family of chips.


Stylus
A pen-like element of a graphics device, moveable by hand and used to identify
and manipulate coordinate data, such as used in a graphics pad or light pen.
In a matrix printer, the element of the print head that produces the dot, a
pin or needle.


Stylus
Atari A4-sized hand-held computer using a stylus as the main input device
rather than a keyboard and mouse and containing handwriting recognition
software. It is STE compatible, running TOS with a 640 x 400 monochrome LCD
touch-sensitive screen accommodating 1 Mb or 4 Mb of main RAM but with no hard
or floppy disk. It is to use Flash RAM or silicon drives - low power plug in
cards - to store data. It is powered by an 8 MHz MC68000 which is underpowered
for the type of software it is to run and the ports are the same as those on
the ST Book. The handwriting character recognition (HCR) code is contained in
the ROMs and tied into the operating system and Desktop such that a gesture in
the Menu Bar area will bring up a window (as invisibly to existing
applications as possible) into which handwritten characters are drawn. As they
are written, the characters are converted to ASCII. When the user is
satisfied, the characters are sent, via the keyboard input stream to the
application. This way, existing applications will have HCR capabilities. The
'hooks' to call the HCR system were intended to be available to software
developers, so that they may call it directly, to recognize ASCII characters,
special character sets or even gestures. The HCR software is a neural-net
simulation. Ahead of its time in 1991-92 it has been officially dropped by
Atari because the cost of making the necessary market penetration was too
high. However, it is also rumoured that the HCR software only recognized the
handwriting of one person - the programmer!


Subdirectory
A directory contained within another parent directory and often called a
folder under GEM.


Subprogram
A labelled module of a program intended to be executed more than once during
the execution of a program being specific to that program and compiled with
it.


Subroutine
A short sequence of instructions written to perform a certain operation, often
available from a library of such routines to be included in or to be called by
different programs. There is really no difference between a routine and a
subroutine except that routines may be constructed from subroutines.


Subscript
That which is printed in a lower position on a line of text and usually of a
smaller size, as in H2O. Also, a value identifying a location in a table or
array, such as list[10].


Subset
A group of items from a set. The ASCII character set is a subset of the ISO-7
character set, for instance.


Substrate
A base or supporting medium. The substrate of a floppy disk is a Mylar disk,
the substrate of a hard disk is an aluminium disk and the silicon chip is that
of an integrated circuit.


Substring
A section of a string.


Suite
A group of items that are used together to accomplish some operation, such as
a programming language program suite.


Superscript
That which is printed in a higher position on a line of text and usually of a
smaller size, as in x².


Supervisor
A group of interrelated programs or routines performing some recurring
operations required in the execution of user programs. They generally form the
backbone of an operating system.


Supervisor mode
The processing state in which the instructions of system software (the
operating system) are executed. The MC68000 runs in one of two operating
modes. The operating system is driven at the first level or supervisor mode.
The user mode is intended for user programs. If a user program tries to access
protected areas of memory, containing systems data (for instance, the first
2,048 bytes containing the exception vectors and system variables) then a bus
error is generated. The processor stops execution of the instruction, saves
the program counter and status register on the stack and branches to a
routine, the address of which is normally contained at address $008. To access
these areas of memory intentionally, the programmer has to make a conscious
effort by placing the processor into supervisor mode. In this way, accidental
and potentially damaging accesses are prevented.


Supervisory channel
A backward channel. A channel of narrower bandwidth than the main channel in a
data communications system that is used to carry acknowledgements and other
supervisory messages, such as ACK or NAK and error detection characters. See
Asymmetric duplex.


Support
That which a manufacturer or supplier gives to users in assisting them with
their products.


Suppress
To prevent from happening, to reduce or limit.


Surface mount device - SMD
Electronic components are normally connected to a circuit board by placing
pins or legs through holes drilled in it. The size and spacing of these holes
limits the size and amount of components that can be placed on the board. More
and more devices are now being soldered directly to the surface of the circuit
board which means that they and the finished product can be made smaller. The
production costs are also cheaper. The biggest disadvantage is that these
components are very difficult to remove and replace for upgrading or repair
purposes.


Surface mount technology - SMT
The technology of soldering electronic components directly to the surface of a
circuit board. See Surface mount device.


Suspend
To temporarily discontinue a program whilst retaining storage and register
values to permit its continuation when conditions permit.


SVGA
Super Video Graphics Adaptor. A screen display standard usually found on IBM
PC compatibles which is a development of the VGA system, giving 800 x 600
pixels with sixteen or 256 colours. Also known as EVGA.


Switch
To change the contents of a storage cell from a 1-bit to a 0-bit or vice
versa. A basic logic circuit, such as an AND, OR or NOT operation. A
conditional branch instruction, such as the C language switch...case or
if...else statements. A manually operated device used to open and close
circuits.


Symbol
A single or group of characters that represent an entity, an operation or
concept in accordance with some convention. For instance, a '£' represents
'Pounds', '+' indicates 'addition' and 'Kb' means 'Kilobytes'.


Symbolic address
A name in source code assigned to a storage location by the programmer. It is
converted to a relative or virtual address by a compiler and to an absolute
address by the operating system when the program is running.


Symbolic logic
A system for solving non-numerical problems by using a set of unambiguous
symbols to represent logical conditions and relationships. See Logic and
Boolean algebra.


Symmetric channel
A duplex circuit where both channels have the same speed and characteristics.
See Asymmetric duplex.


Symmetric circuit
A full-duplex data transmission circuit.


SYNC
SYNChronization.


Synchronization
The condition in which two or more operations are performed with common
timing. Also, the process of adjusting event timing of a system or functional
unit so that events occur in time frames established by another system or
functional unit. Also, the process of aligning numeric data to the correct
word or half-word boundary in memory for performing arithmetic operations.


Synchronization pulses
Pulses sent from one system or functional unit to another for purposes of
establishing, checking and adjusting event timing.


Synchronous
A system or operation in which events occur in a sequence of fixed time
frames.


Syntax
The rules or practice governing the placement of words of different types in
relation to each other in a sentence. In a programming language, the rules for
forming valid instructions or statements.


Synthesizer
A device holding bit-pattern representations of analogue waves (speech,
musical instrument) and performing the digital to analogue conversion to
produce sound.


Sysop
SYStems OPerator. The person in charge of a local area network or a node on a
wide area network. The term commonly refers to a person who owns and/or runs a
bulletin board system.


System
A group of complementary elements organized to work together to perform some
operation, such as a computer, its display, storage (disks) and peripherals
(printer, modem). Also, pertaining to the control and management of processing
functions.


System crash
A complete failure of the operating system caused by an attempt to execute an
illegal instruction or access illegal and protected memory.


System data
Data held in a file and used by the operating system to control processing
operations, such as the DESKTOP.INF file.


System disk
A disk containing the operating system, in a system where it is loaded from
disk and not stored in ROM, such as in MS-DOS-based PCs.


System font
The operating system font used for screen display. On the ST-Falcon range
there are three, a 16 x 8 pixel character font, an 8 x 8 font and a 6 x 6 font
used on the Desktop for icon labels, for instance. All three are monospaced
and can be replaced by others using appropriate software.


System program
A program other than an application, a program concerned with the operating
functions of the computer but not necessarily part of the operating system.


Systems analysis
The job of determining how best to implement particular user applications on
particular systems, typically transferring the techniques of 'manual' methods
into a computer system.


System variables
The addresses in a protected area of memory storing important system data
needed by the operating system.


System variables - TOS
The addresses and meanings of the system variables will not change in future
revisions of TOS except to be added to. Any other variables in RAM, routines
in the ROM or vectors below $400 that are not documented here will, and have
been known to change, so if you are a programmer do not use them. It is
important not to depend on undocumented variables or ROM locations.

The system variables start in low RAM directly above the exception vectors at
address $400 (1,024) and space for them continues to address $7FF (2,047)
although the highest to date is at $600. Please note that these can only be
accessed in MC680x0 supervisor mode as these address ranges are protected.

All the system variable names are official Atari names (they do, however,
change from time to time), with one or two adjustments by the author (themd
and _bufl have personalized suffixes). Each starts with its address followed
by its name, the length of its value and an example value in hex taken from
TOS 1.4. A long = 32 bits, a word = sixteen bits and a byte = eight bits.

  Table S7: TOS System Variables

  Address  Name             Length     Typical TOS 1.4 value
  in hex
  $400     etv_timer        long       $FCB36C
           GEM event timer interrupt chain vector.

  $404     etv_critic       long       $FDD20C
           Critical error chain handler.

  $408     etv_term         long       $FC0652
           GEM vector for ending a program.

  $40C     etv_xtra         5 longs    $0 $0 $0 $0 $0
           Additional GEM vectors.

  $420     memvalid         long       $752019F3
           If it contains the magic number shown it validates, together with
           memval2, the configuration of the memory controller memcntrl and
           indicates a successful cold start. As of TOS 1.2, memval3 must also
           be correct.

  $424     memcntrl         word       $A00
           The value is a copy of the configuration value of the memory
           controller. Only the low nybble of the high byte (bits 8-11)
           applies, ST only.
           Value     Meaning
            0          256 K
            4          512 K
            5        1,024 K
            8        2,048 K
            9        2,560 K
           10 ($A)   4,160 K

  $426     resvalid         long       $31415926
           If the value is as shown on a system reset, the system will jump to
           the address shown in resvector.

  $42A     resvector        long       $66BE2
           A system reset will jump to the vector contained here if resvalid
           contains the magic number as above. The return address is placed in
           CPU register A6.

  $42E     phystop          long       $400000
           Physical top of ST RAM (not Alternative TT RAM). It contains a
           pointer to the first unusable byte. RAM disks, for instance will
           set phystop to below their memory space giving what appears to be a
           strange value at first.

  $432     _membot          long       $A84E
           Bottom of available ST RAM, the start of the TPA. The GEMDOS free
           memory is initialized from this value.

  $436     _memtop          long       $3F8000
           Top of available ST RAM, the end of the TPA and usually the start
           of the video RAM. The GEMDOS free memory is initialized up to this
           value.

  $43A     memval2          long       $237698AA
           If it contains the magic number shown, it validates the memory
           configuration together with memvalid and indicates a successful
           cold start.

  $43E     flock            word       $0
           A non-zero value indicates that a disk (DMA registers) access is in
           progress and prevents TOS or another process from accessing the DMA
           registers at the same time.

  $440     seekrate         word       $3
           Floppy disk seek rate. The value is contained in bits 0 and 1 only:
           Value    Seek rate
            0        6 ms
            1       12 ms
            2        2 ms
            3        3 ms (default)

  $442     _timer_ms        word       $14
           The interval between two system timer calls and should be the value
           shown ($14 = decimal 20 ms) which corresponds to 50 Hz.

  $444     _fverify         word       $FF00
           Floppy verify flag. If the value is non-zero a verify is performed
           after each disk write operation. The default is to do a verify.

  $446     _bootdev         word       $2
           This contains the device number the system was booted from, where 0
           = drive A: and 2 = drive C: etc.

  $448     palmode          word       $0
           When non-zero, the colour system is in PAL video mode (50 Hz), if
           zero the colour system is in NTSC video (60 Hz) mode.

  $44A     defshiftmd       word       $0
           Default colour video resolution. If the ST resets from monochrome
           mode to colour mode, the resolution is taken from here where 0 =
           low and 1 = medium resolution. First byte only.

  $44C     sshiftmd         word       $200
           A copy or shadow of the shiftmd hardware register at $00FF8260
           which indicates the current ST SHIFTER mode for screen resolution.
           The value is contained in the high byte:
           Value    Resolution
            0         320 x 200 x 4 planes (ST low resolution)
            1         640 x 200 x 2 planes (ST medium resolution)
            2         640 x 400 x 1 plane (ST high resolution)
            3       Any Falcon resolution
            4         640 x 480 x 4 planes (TT medium resolution)
            6       1,280 x 960 x 1 plane (TT high resolution)
            7         320 x 480 x 8 planes (TT low resolution)

  $44E     _v_bas_ad        long       $3F8000
           Pointer to the physical video RAM, the logical screen base. For TOS
           versions before TOS 1.6 screen RAM has to be 256 byte aligned,
           otherwise it can be word (sixteen bits) aligned.

  $452     vblsem           word       $1
           VBL semaphore. If this value is zero then a vertical blank routine
           is not executed. If the value is one then VBLs are enabled.

  $454     nvbls            word       $8
           Number of vertical blank routines which defaults to a value of
           eight. It is the number of long words that _vblqueue points to.

  $456     _vblqueue        long       $4CE
           Pointer to a list (nvbls long) of routines that will be executed
           during a vertical blank.

  $45A     colorptr         long       $0
           If this value is non-zero it is a pointer to a colour palette of
           sixteen values which are loaded on the next vertical blank into the
           hardware registers.

  $45E     screenpt         long       $0
           Pointer to the start of the screen memory which will be loaded into
           the hardware register pointing to the base of the physical screen
           on the next vertical blank. If the value is zero then no new
           address is to be set.

  $462     _vbclock         long       $7F128
           Count of the number of vertical blank interrupts since the last
           reset.

  $466     _frclock         long       $7F12F
           Count of the number of vertical blank interrupt routines that have
           been executed and not blocked by vblsem.

  $46A     hdv_init         long       $FC16BA
           The address of the hard disk initialization routine. If zero then
           no hard disk is installed.

  $46E     swv_vec          long       $FC0030
           Vector for monitor change. The system continues at the address
           contained here if the monochrome monitor detect signal is changed
           (i.e. switching to a colour monitor from a monochrome one or vice
           versa). The vector is normally the start of the operating system
           (after the operating system header block) thus performing a reset.

  $472     hdv_bpb          long       $A91E
           Address of a routine to get a hard disk's BIOS Parameter Block
           (BPB). If zero then no hard disk is installed.

  $476     hdv_rw           long       $A92E
           Vector to a routine to read and write to a hard disk. If zero then
           no hard disk is installed.

  $47A     hdv_boot         long       $FC1CC6
           Vector to a routine to boot from a hard disk. If zero then no hard
           disk is installed.

  $47E     hdv_mediach      long       $A93E
           Vector to a routine to get a hard disk's media change mode. If zero
           then no hard disk is installed.

  $482     _cmdload         word       $0
           If the boot program sets this to a non-zero value an attempt is
           made to load and execute a program called COMMAND.PRG from the boot
           device. This can be a shell or an application which will replace
           the Desktop.

  $484     conterm          byte       $6
           Contains some attribute bits for the console output:
           Bit      Meaning
            0       Key click on/off
            1       Key repeat on/off
            2       Bell on/off (The tone when [Cntl-G] or ASCII 7 is sent to
                    console)
            3       kbshift on/off. If set it enables BIOS function Bconin()
                    (and GEMDOS Cconin() and others) to return the key shift
                    status. Defaults to off.

  $485     reserved

  $486     trp14ret         long       $0
           Return address for a TRAP #14.

  $48A     criticret        long       $0
           Return address for critical error handler (etv_critic) routine.

  $48E     themd_m_link     long       $0
           Memory descriptor filled in by the BIOS function Getmpb(). It
           indicates to GEMDOS the size of the TPA. This and the next three
           system variables form part of the structure which cannot be changed
           once it has been initialized:
           typedef struct md
           {
             struct md *m_link;        /* next MD                  */
             void *m_start;            /* start of block           */
             long m_length;            /* length of block in bytes */
             BASEPAGE *m_own;          /* owner's basepage         */
           } MD;

  $492     themd_m_start    long       $A84E
           See themd_m_link.

  $496     themd_m_length   long       $4909C
           See themd_m_link.

  $49A     themd_m_own      long       $5FB2
           See themd_m_link.

  $49E     ___md            2 words    $0 $0
           Space for additional memory descriptors.

  $4A2     savptr           long       $90C
           Pointer to a save area for the processor registers after a BIOS
           call.

  $4A6     _nflops          word       $1
           Number of floppy disk drives attached to the system.

  $4A8     con_state        long       $FCA320
           Console state. Vector for screen output which can be set by various
           VT52 Esc functions.

  $4AC     save_row         word       $B
           Temporary store for the cursor position with the VT52 Esc Y
           command.

  $4AE     sav_context      long       $0
           Saved processor context. Pointer to a temporary area for exception
           handling.

  $4B2     _bufl_sect       long       $4E1F8
           Pointer to first GEMDOS Buffer Control Block used to store data
           sectors.

  $4B6     _bufl_FAT        long       $50FB0
           Pointer to second GEMDOS Buffer Control Block used to store FAT and
           directory sectors. The Buffer Control Block has the structure:
           typedef struct _bcb
           {
             struct _bcb *_link;       /* point to next BCB    */
             int b_neg1;               /* = -1                 */
             int b_private[5];         /* private parts        */
             char *b_buf;              /* point to data buffer */
           } BCB;

  $4BA     _hz_200          long       $177D
           Counter for the 200 Hz system timer and used to seed the Random()
           function.

  $4BE     the_env          4 bytes    $0 $0 $0 $0
           Default environment string, containing four zero bytes. It is
           currently not used by TOS and is reserved by Atari.

  $4C2     _drvbits         long       $1FF
           32-bitmap of connected drives. Bit 0 is drive A:, bit 1 drive B:,
           bit 2 drive C: and so on. The shown value equals binary %111111111
           which is drives A: to I: inclusive. If only one floppy drive is
           connected, both floppy bits will be set, drive B: being a virtual
           drive.

  $4C6     _dskbufp         long       $181C
           Pointer to a 1024 byte disk buffer also used for GSX graphic
           operations and should not be used by interrupt routines.

  $4CA     _autopath        long       $0
           Pointer to AUTO folder path. Usually zero to indicate default.

  $4CE     _vbl_list        8 longs    $FD0A8C $0 $0 $0 $0 $0 $0 $B19E
           Eight vectors pointing to the installed VBL routines.

  $4EE      _prt_cnt        word       $FFFF
           Pressing [Alt-Help] to dump the screen to the printer increments
           this value by one from the default value of -1 ($FFFF) to zero. The
           screen dump code will only dump the screen when this contains a
           value of zero. Pressing [Alt-Help] again will abort the dump.

  $4F0     _prtabt          word       $0
           Printer abort flag due to a time out.

  $4F2     _sysbase         long       $FC0000
           Pointer to the start of the operating system header block in ROM or
           RAM. See System header block.

  $4F6     _shell_p         long       $0
           Points to global shell specific information.

  $4FA     end_os           long       $A84E
           Pointer to the byte after the last byte of the low RAM used by the
           operating system. This is the equivalent to the start of the TPA.

  $4FE     exec_os          long       $FD3B34
           Pointer to the start of the shell that is executed by the BIOS
           after the system initialization. This is normally the AES start-up
           code.

  $502     scr_dump         long       $FC0D0C
           Pointer to the screen dump routine.

  $506     prv_lsto         long       $FC3392
           Vector for getting the printer (PRN: or LST:) output status for the
           screen dump routine.

  $50A     prv_lst          long       $FC32F6
           Vector for the printer (PRN: or LST:) output for the screen dump
           routine.

  $50E     prv_auxo         long       $FC3408
           Vector for getting the serial (SER: or AUX:) output status for the
           screen dump routine.

  $512     prv_aux          long       $FC3422
           Vector for the serial (SER: or AUX:) output for the screen dump
           routine.

           The following were introduced with TOS 1.2

  $516     pun_ptr          long       $C70A
           Pointer to the hard disk driver data pun_info structure. See
           PUN_INFO.

  $51A     memval3          long       $5555AAAA
           Contains the shown magic number if a cold start was successful. See
           memvalid and memval2.

  $51E     xconstat         8 longs    $FC0652 $FC33A6 $FC3494 $FC32A6
                                       $FC0652 $FC0652 $FC0652 $FC0652
           Eight pointers to routines for getting input status of a character
           device jumped to by BIOS function 1, Bconstat(). Each applies to a
           different device starting from 0 to 7. Where there isn't a specific
           physical device the routine points to a RTS command, as at $FC0652
           in TOS 1.4. The devices are:
           Device   Meaning
            0       Parallel printer port
            1       Auxiliary device, currently-mapped serial port
            2       Console device
            3       MIDI port

  $53E     xconin           8 longs    $FC3372 $FC33BE $FC34AA $FC32C0
                                       $FC0652 $FC0652 $FC0652 $FC0652
           Eight pointers to routines for getting a character from a device
           jumped to by BIOS function 2, Bconin(). The devices are the same as
           for Bconstat().

  $55E     xcostat          8 longs    $FC3392 $FC3408 $FC34E0 $FC344A
                                       $FC326A $FC0652 $FC0652 $FC0652
           Eight pointers to routines for getting the output status for
           devices 0 to 7 jumped to from BIOS function 8, Bcostat(). There are
           two additional devices:
           Device   Meaning
            4       Keyboard port (IKBD)
            5       Raw screen device
           Due to a bug, the 4th address is for IKBD and the 5th for MIDI.

  $57E     xconout          8 longs    $FC32F6 $FC3422 $FCA30A $FC327A
                                       $FC345C $FCA2FE $FC0652 $FC0652
           Eight pointers to routines for writing a character to a device
           jumped to by BIOS function 3, Bconout(). The devices are the same
           as for Bcostat().

           The following were introduced with TOS 1.6

  $59E     _longframe       word       $0
           If this value is non-zero the CPU has long exception stack frames
           (an extra word after the SR and PC) and is therefore not a MC68000.
           A value of zero signifies a short stack frame and therefore a
           MC68000 processor. Although introduced with TOS 1.6 it can be used
           with earlier TOS versions.

  $5A0     _p_cookies       long       $66EB6
           Pointer to Cookie Jar list.

  $5A4     fmemtop          long       $0
           Top of available Alternative Fast RAM (TT RAM) if fmemvalid is
           correct. If the value is zero there is no Fast RAM. A value of
           $1400000 means 4 Mb of Fast RAM which starts at $1000000.

  $5A8     fmemvalid        long       $0
           Contains the magic number $1357BD13 if Alternative Fast RAM is
           installed and validates the configuration of the memory controller.
           However, this value is also present in TOS 1.6 to TOS 2.06 where
           Alternative RAM is impossible but the value of fmemtop is zero
           anyway.

  $5AC     bell_hook        long       $0
           Pointer to a TSR bell routine.

  $5B0     kcl_hook         long       $0
           Pointer to a TSR key-click routine.

  $600     patchzone        long       $BADC0DE
           Area for patching, set to shown value if empty (usually TOS 1.4) or
           zero. Introduced with TOS 1.4.


S
253 entries
EOF