home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Games of Daze
/
Infomagic - Games of Daze (Summer 1995) (Disc 1 of 2).iso
/
x2ftp
/
msdos
/
utils
/
diagdemo
/
amidiag.hlp
< prev
next >
Wrap
INI File
|
1994-08-24
|
34KB
|
971 lines
[Main menu]
The AMIDiag 4.5 main menu has the following items:
{System Board menu},
{Memory menu},
{Hard disk menu},
{Floppy menu},
{Keyboard menu},
{Video menu},
{Misc menu},
{User menu},
{Options menu}.
Use the left and right arrow keys to select a menu.
Then use the up and down arrow keys to select a test.
Press <Enter> to run the test. Press <F1> at any time to
display a Help screen.
If using a mouse, you can double-click on a menu item to select
that item. To select a test to be run in batch mode, single-click
on the test. Single-click on a selected test to deselect it.
See also - {About AMIDiag}
[About AMIDiag]
AMIDiag 4.5 provides the most comprehensive tests for advanced
PC technologies like {EISA}, {PCI}, {Plug&Play}, and {PCMCIA}.
Equally outstanding is the SYSINFO utility that is part of AMIDiag.
SYSINFO can detect resource allocation (such as IRQ and DMA
assignments) for SCSI controllers, IDE controllers, sound cards,
CD-ROM drives, and many other types of devices.
[System board menu]
This set of diagnostic tests checks motherboard functions.
The tests are:
{Basic Functionality test},
{CPU Protected Mode test},
{Processor speed test},
{Coprocessor test},
{DMA controller test},
{Interrupt controller test},
{Timer test},
{Real time clock test},
{CMOS validity test},
{EISA system test},
{PCI system test}
See also - {Main menu}
{About AMIDiag}
[Memory menu]
This set of tests checks the memory functions. The tests are:
{BIOS ROM test},
{Parity test},
{Pattern test},
{Walking 1's test},
{Walking 0's test},
{Random read/write test},
{Address test},
{Refresh test},
{Cache memory test}
See also - {Main menu}
{About AMIDiag}
[Hard disk menu]
This set of tests checks the hard disk drive functions.
The tests are:
{Hard disk format},
{Auto interleave},
{Media analysis},
{Performance test},
{Seek test},
{Read/verify test},
{Check test cyl},
{Force bad tracks}
See also - {Main menu}
{About AMIDiag}
[Basic Functionality Test]
The Basic Functionality Test runs in one of two modes,
depending on the {CPU} installed in the system.
If the processor is an 80286, the test is run in 16-bit
mode and checks:
* the functionality of the 16-bit registers,
* {16 bit flags}, and
* special 80286 instructions.
If the processor is an 80386 or higher:
The test is run in 32-bit mode and checks:
* the functionality of the 32-bit registers,
* {32 bit flags}, and
* special 80386 and 80486 instructions.
[CPU Protected Mode Test]
The CPU Protected Mode Test tests the {protected mode}
features of Intel 80286 and above {CPU}s.
The processor is switched to protected mode and then all
protected mode special instructions are tested.
For example, a protected mode selector is loaded with a
segment limit of 256 bytes. Then an LSL (Load Segment Limit)
instruction is used to make sure it returns the segment
limit properly.
[Processor Speed Test]
This test determines and displays the CPU clock speed by
measuring the time taken to execute a specific instruction.
The time is calculated by using a separate clock source
with a known frequency.
Special care has been taken to eliminate the effect of any
{prefetch queue} and cache memory. The CPU speed is displayed
in bar chart form. The CPU clock speeds of commercially
available CPUs are displayed on the scale for reference.
[Coprocessor Test]
This test checks the functionality of the 80287 or 80387
math coprocessor.
The tests include loading and storing the control and
status word, data transfer between CPU and NPX, and
exception checking while the data transfer is in progress.
[DMA Controller Test]
The {DMA} Controller Test is a series of read/write tests
on the memory address registers and page registers of DMA
controllers 1 and 2.
[Interrupt Controller Test]
This test performs a series of read/write tests on the {interrupt}
mask registers of the interrupt controller. It also checks for
stray interrupts by setting the mask for all interrupts and
then enabling the processor interrupt.
[Timer Test]
This test checks the accuracy of the timer count by
calibrating it against the periodic interrupt of the real
time clock ({RTC}).
[Real Time Clock Test]
This test checks the accuracy of the real time clock by
calibrating it against the timer (IRQ 0) interrupt.
[CMOS Validity Test]
This test checks the condition of AT {CMOS} RAM
(non-volatile memory).
The test makes sure that the CMOS battery is in good
condition and that the CMOS RAM checksum is correct.
[EISA system test]
This test runs on {EISA} systems only.
This test performs read/write/compare tests on some
EISA-specific {DMA} and {interrupt} controller registers.
It also checks the EISA software NMI and fail-safe timer.
[PCI system test]
This test runs on {PCI} systems only.
This test scans the PCI bus and finds all PCI devices.
Then it uses a different procedure to find the same devices.
It checks for all valid combinations of PCI bus number, device
number and function number. It also checks the validity of PCI
BIOS32 service directories and the generation of PCI special
cycles.
[BIOS ROM Test]
The {BIOS ROM} test checks the data path of the BIOS
ROM and also assures that the ROM is write-protected.
A shadowed ROM may remain write-enabled by mistake, which may
cause serious problems.
[Parity Test]
This test reads all memory locations and checks for parity
errors in the entire memory space.
All IBM AT-compatible systems include memory {parity} checking
circuitry. When the {CPU} accesses a memory location that has
a parity error, a bit is set in a specific register and an
NMI (nonmaskable interrupt) is generated. The AMIDiag parity
test captures the interrupt so that the system does not crash
even when a parity error is encountered, Then it reads the
entire memory region for parity errors.
[Pattern Test]
This test performs a comprehensive read/write test on the
entire memory space, using worst-case bit patterns
such as AA55 (1010101001010101).
This test will identify most memory problems.
[Walking 1's Test]
This test identifies shorts on data lines. The following
diagram explains how this test works.
┌───────────────────────────────────────────┐
│ M E M O R Y D A T A │
└──┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌──┘
│D7│ │D6│ │D5│ │D4│ │D3│ │D2│ │D1│ │D0│
└┐┌┴─┴┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘
BUS ───────┼┼───┼┼───┼┼───┼┼───┼┼───┼┼───┼┼───┼┼────────────
└┘ └┘ └┘ └┘ └┘ └┘ └┘ └┘
This test writes a rolling 1s pattern in memory. It first
writes 1, then 2, then 4, then 8, then 16, etc, so that in the
written data, only one bit is on at a time.
Consider the memory chip shown above. It has a short between
data bits 7 and 6 (shown as D7 and D6). The walking 1s
test will pass up to the data pattern 20h (bit 5 on). When this
test writes 40h (bit 6 on), it reads back 0C0h (bits 7 and 6 on),
because bits 7 and 6 are shorted together.
The walking 1s test is useful in isolating data shorts.
[Walking 0's Test]
This test identifies open data lines. The following
diagram explains how this test works.
┌───────────────────────────────────────────┐
│ M E M O R Y D A T A │
└──┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌──┘
│D7│ │D6│ │D5│ │D4│ │D3│ │D2│ │D1│ │D0│
└┐┌┴─┴┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘
││ └┘ ││ ││ ││ ││ ││ ││
BUS ───────┼┼────────┼┼───┼┼───┼┼───┼┼───┼┼───┼┼────────────
└┘ └┘ └┘ └┘ └┘ └┘ └┘
This test writes a rolling 0s pattern in memory. It first
writes FEh, then FDh, then FBh, etc, so that in the written
data, only one bit is 0 at a time.
Consider the memory chip shown above. It has an open data pin
in bit position 6 (shown as D6). The walking 0s test will pass
up to the data pattern DFh (bit 5 off). When this test writes
BFh (bit 6 off), it reads back FFh, because bit 6 is open and
will always appear as set.
The walking 0s test is useful in isolating data opens.
[Random read/write test]
This test uses a pseudo-random number generator to
generate random addresses to the entire memory area. It
then writes random data to the location, reads
it back, and compares the data read with the data written.
Most motherboards have 32 KB 50 to 2 MB of cache memory.
However, depending on the cache algorithm, soft or flaky errors
in dynamic memory are sometimes difficult to catch. If a
memory test progresses sequentially, after some time it starts
accessing only cache memory. The random read/write test defeats
the cache strategy and accesses the DRAM as much as possible.
This test is also useful in finding cache loading problems
in motherboards. Since this test produces cache misses more
frequently than any other application program, this test
exercises the cache loading thoroughly.
[Address Test]
This test checks for shorts and opens on address lines.
The following diagram explains how the address test works.
┌───────────────────────────────────────────┐
│ M E M O R Y A D D R E S S │
└──┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌──┘
│A7│ │A6│ │A5│ │A4│ │A3│ │A2│ │A1│ │A0│
└┐┌┴─┴┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘ └┐┌┘
BUS ───────┼┼───┼┼───┼┼───┼┼───┼┼───┼┼───┼┼───┼┼────────────
└┘ └┘ └┘ └┘ └┘ └┘ └┘ └┘
The address test writes a value in one location of memory
and then scans the entire memory region to find a
reflection of that value. The address locations are so
selected that in the complete address, only one bit
remains set at a time. For example,, this test writes to
memory locations 1, 2, 4, 8, 16, etc.
In the memory chip shown above, address bits 7 and 6 are shorted
together. Any value written to xxxxxx40 will also appear at
xxxxxC0. On the other hand, if bit 7 if open, the address
xxxxxx01 becomes the same as xxxxxx81, since address bit 7
always remains high. The value written at xxxxxx01 will be
duplicated at xxxxxx81.
[Refresh Test]
This test makes sure the refresh circuitry is functioning and
measures the refresh interval.
Bit 4 of I/O port 0061h is set every time refresh takes
place. By polling port 0061h over a known period of time, it is
possible to calculate the refresh interval. An error is reported
if this interval is not within +/- 5 percent of the standard
refresh interval of 15 microseconds.
[Cache Memory Test]
If AMIDiag detects {cache} memory, this test displays the
internal and external cache memory size.
[Hard Disk Format]
THIS TEST IS DESTRUCTIVE. IT ERASES ALL DATA ON THE DISK.
Use the Hard Disk Format Test to integrate a new hard
disk into the system or reformat a used hard disk that
has developed some bad tracks because of aging or poor
handling. DO NOT RUN THIS TEST ON SCSI OR IDE DRIVES.
[Auto Interleave]
Run Auto Interleave to optimize hard disk performance.
AMIDiag calculates the optimum interleave value by measuring
the data transfer rate for several interleave factors.
The hard disk is formatted with the interleave factor that
has the fastest data transfer rate.
DO NOT RUN THIS TEST ON SCSI OR IDE DRIVES.
[Media Analysis]
The Media Analysis routine runs a series of tests to
locate bad tracks.
DO NOT RUN THIS TEST ON SCSI OR IDE DRIVES.
[Performance Test]
The Performance Test determines the Data Transfer Rate,
the Sequential Seek Time, and the Random Seek Time.
The Data Transfer Rate is measured in kilobytes per second.
The Seek times are measured in milliseconds.
[Seek Test]
The Seek Test determines the head movement capability of
the hard disk by seeking to a specified cylinder and
head range.
A series of sequential seeks is performed, followed
by a series of random seeks.
[Read/Verify Test]
This test performs sequential and random read and verify
operations on the specified cylinder and head range.
[Check Test Cylinder]
The last cylinder on the hard disk is the test cylinder.
This test performs write and verify tests on all
sectors in the test cylinder.
If all sectors on the test cylinder are bad, BIOS POST
issues a "C (or D): Drive failure" message at system boot.
[Force Bad Tracks]
This routine allows you to mark a set of tracks as faulty.
If you did not enter the bad tracks before performing
a low level format, use this option to enter bad tracks at
any time.
[Diskette Format Test]
This test determines the ability of the floppy disk
controller to perform low-level formatting.
It also determines the condition of the magnetic
media inside the diskette.
[Drive Speed Test]
This test determines the rotational speed of the floppy
drive.
The ideal rotational speed, expressed in RPM
(revolutions per minute), is:
* 360 RPM for high density (1.2 MB or 1.44 MB)
drives, and
* 300 RPM for low density (360 KB or 720 KB) drives.
[Random Read/Write Test]
This test checks the random seek, read, and write
capability of the floppy drive.
The diskette used in this test must be formatted.
[Sequential Read/Write Test]
This test checks the sequential seek, read, and write
capability of the floppy drive.
The diskette used in this test must be formatted.
[Disk Change Line Test]
This test verifies the disk change line capability
of the floppy drive.
The disk change line is only found in high density
(1.44 MB or 1.2 MB) drives. It allows the operating
system to recognize that a diskette was
removed from the drive and a new diskette inserted.
[Controller Test]
The Controller Test issues a Self Test command to the
keyboard controller and checks for an OK response.
[Scan/ASCII Code Test]
The Scan/ASCII Code Test determines whether the pressed
key matches its respective Scan and ASCII codes.
[Keyboard Clock Line Test]
The Keyboard Clock Line Test verifies that the keyboard
clock line is working properly. This test makes sure
the keyboard clock line is not stuck on high or low).
[Keyboard Data Line Test]
The Keyboard Data Line Test verifies that the keyboard
data line is working properly. This test makes sure that the
keyboard data line is not stuck on high or low.
[Adapter Test]
This option tests the video display memory at B800h or B000h,
depending on whether the display adapter is color or monochrome.
Since random characters are written in the display memory and
then read back, the screen may show some irregular characters
and colors while the test is being executed.
This test can be run with both monochrome and color display
adapters.
[Attribute Test]
This option tests the display attributes. It displays a
screen with a blinking line, reverse video line, high
intensity line and lines in eight colors. The screen is
displayed in video mode 03h (video mode 07h is used
for monochrome).
This test can be run with both monochrome and color display
adapters.
[80x25 Display Test]
This routine tests the 80x25 character set of the display
adapter, displaying the entire character set in black and
white, then in reverse video. The program uses video mode
3 (7 for monochrome).
This test can be run with monochrome and color display
adapters.
[40x25 Display Test]
This option tests the 40x25 character set of the display
adapter, displaying the entire character set in black
and white, then in reverse video. The program uses video
mode 1 for this test.
This test can be run with both monochrome and color display
adapters.
[320x200 Graphics Test]
This test displays a black and white 9 x 13 window and then
redisplays it in reverse video. Then it displays a three
color screen, a screen filled with random dots of random
colors, then a blank screen, and finally 256 colors.
This test uses video modes 04h and 13h.
[640x200 Graphics Test]
This screen displays three black and white boxes, then displays
a blank screen, then an all white screen filled with dots.
The blank screen is then redisplayed.
This test can be run only with color display adapters.
[Page Selection Test]
Color display adapters usually have several pages on
which text can be displayed. BIOS interrupt INT 10h function
05h accesses different video pages.
This test writes all 0s on page 0, all 1s on page 1,
all 2s on page 2, and so on. Then it displays all video pages
to make sure each video page functions properly.
This test can be run only with color display adapters.
[Color Test]
This test displays all possible color combinations in
the foreground, background, and border.
This test can be run only with color display adapters.
[640x350 Graphics Test]
This test displays a 16-color screen, then fills the
screen with random colors, then again displays a blank
screen.
This test uses EGA video mode 0Fh if an EGA monochrome
monitor is detected. It uses EGA mode 10h if an EGA color
monitor is detected.
This test can only be run with EGA or higher video
adapter.
[640x480 Graphics Test]
This test displays a 16-color screen, then fills the
screen with random colors, then displays a blank screen.
This test uses VGA mode 11h if a VGA monochrome monitor
is detected. It uses VGA mode 12h if a VGA color monitor is
detected.
This test can only be run with VGA or higher video
adapters.
[Serial Port Test]
This test checks the serial ports found in the global
memory locations 40:0 to 40:7. A maximum of four serial
ports (COM1 through COM4) are tested. The communication
parameters, such as the number of data bits, number of stop
bits, parity type, etc.) can be individually selected
for each serial port. All parameters can be entered in a
single edit window.
The serial port tests are:
1 Register test,
2 Interrupt ID test,
3 Internal loopback test,
4 Line status test,
5 Modem control register test,
6 Data transfer test (baud rates - 300 bps to 9600 bps),
7 External loopback test.
[Parallel port test]
This test checks the parallel ports found in the global
memory locations 40:8 to 40:d. A maximum of three
parallel ports (LPT1 through LPT3) are tested. The
test parameter window asks if a printer or external loopback
plug is connected. If none is connected, only the register
read/write test on the parallel port data buffer is
performed. Otherwise, the following tests are performed:
1 Register test,
2 IRQ activation test,
3 Pattern printing,
4 Bold letter printing,
5 Compressed mode printing,
6 Printer form feed test.
If a printer is connected, check the printer output.
If an external loopback is connected, there is no printed
output, but the response from the parallel port controller
is checked.
[Set/view run time parameters <F2>]
Selecting this option is the same as pressing <F2>
from the main menu.
This option allows you to specify different groups
of parameters:
* Hard disk test parameters
* Hard disk types
* Floppy test parameters
* Batch mode parameters
You can specify the physical dimensions of the hard disk as
well as the starting and ending cylinder numbers and head
numbers where the tests will be executed.
[Load/save run time parameters <F7>]
Selecting this option is the same as pressing <F7>
from the main menu.
This option allows you to save certain run time parameters
in an ASCII file with a .SAV file extension, or to load
these parameters from a .SAV file.
The parameters that are saved include information on the
tests that have been selected for batch mode execution
(by pressing <F3>, <F4>, or <F8>), the batch mode run time
option (time bound, pass bound, or continuous), the error
logging option, the error log file name and heading, and
other test parameters.
[System Information]
This option allows you to run SYSINFO.EXE from
within AMIDiag.
SYSINFO.EXE displays memory block details, a software
interrupt summary, IRQ allocation information, CMOS
information, the contents of AUTOEXEC.BAT and
CONFIG.SYS files, and lots of other information.
SYSINFO.EXE can also be run from the DOS command line
as a standalone program.
[Configuration program]
This program allows you to run CONFIG.EXE from within
AMIDiag. CONFIG.EXE can also be executed from the DOS
command line.
CONFIG allows you to define memory organization and CPU
components graphically, so that in case of error, the
exact location of the component is displayed on a
graphics screen in AMIDiag.
CONFIG also allows you to integrate cache controller
programs and user-defined diagnostic programs with AMIDiag.
CONFIG displays the faulty memory chip or CPU component when
called by AMIDiag via a special command line option.
It also loads or saves configuration data to or from an ASCII
file.
[Report generation]
This option allows you to specify if error messages are
logged to a disk file, a printer, or a serial port.
If you select "Yes" and the previous selection was "No",
type the name of the log file as well as an optional
ASCII header string for identification.
If you select "Yes" and the previous selection was "Yes"
and the log file name is the same, choose whether the new
error log file is appended to the old file or the old file
is rejected and a new error log file is started.
Similarly, if you select "No" and the previous selection
was "Yes", you must discard or save the old log file.
[Change color settings <F10>]
This selection is the same as pressing <F10> from the
main menu. By repeatedly pressing <F10>, you can rotate
the color scheme and see the different color sets
available.
When you select a color set, press <Enter> to save that
color set and return to the main menu.
[Virus scanning]
This is a new feature in AMIDiag that will let you SCAN
whole or part of your disk for virus. This option will
load the AMU(Anti-viral Maintenance Utility) that provides
a graphical user interface for virus scanning.
[Toggle speaker on/off]
This option allows you to enable or disable the system
speaker.
If the speaker is disabled, memory tests and others tests
that issue beeps will run in quiet mode.
The speaker can be enabled by selecting "Speaker on"
in the dialog box displayed by this option.
[DOS shell]
This option allows you to return to the DOS prompt
temporarily.
You can issue all DOS commands from the DOS shell.
Typing "Exit" from the DOS prompt returns to AMIDiag.
[Exit AMIDIAG]
Select this option to Exit AMIDiag. You will have the option
of either returning to DOS or system reset.
[CPU]
CPU is acronym for Central Processing Unit. It is the
brain of the computer, where building blocks for arithmetic
and logical operations and control circuitry is located.
In IBM PC market, the Intel 80x86 CPUs are most popular.
Other vendors who are making 80x86-compatible CPUs
include IBM, Cyrix, AMD, Texas Instrument etc.
[16 bit flags]
The CPU flag is a special register which indicate the status
of the operations done by CPU. The different elements of the
flag register are the carry flag, the zero flag, the sign
flag etc. For instance, when the CPU performs an ADD
instruction, all the three flags mentioned before (carry flag,
zero flag, etc.) is modified.
The 80286 CPU flag register has 16 bits in it. The "16 bit
flags" refer to a flag format compatible to 80286 CPU.
16 bit EFLAGS
1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0
5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
│ │N│I O│O│D│I│T│S│Z│ │A│ │P│ │C│
│0│F│P L│F│F│F│F│F│0│0│F│0│F│1│F│
│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘
0 1 1 1 0 0 1 0 0 1 0 0 0 1 1 0
NF Nested task flag (bit 14).
IOPL Input/Output privilege level (bits 13-12).
IF Interrupt enable flag (bit 9).
TF Trace flag (bit 8).
SF Sign flag (bit 7).
ZF Zero flag (bit 6).
AF Auxiliary Carry flag (bit 5).
PF Parity flag (bit 2).
CF Carry flag (bit 0).
[32 bit flags]
The CPU flag is a special register which indicate the status
of the operations done by CPU. The different elements of the
flag register are the carry flag, the zero flag, the sign
flag etc. For instance, when the CPU performs an ADD
instruction, all the three flags mentioned before (the carry flag,
zero flag, etc.) is modified.
80386 and above CPUs have 32 bits in the flag register. The
"32 bit flags" is a flag format compatible with these CPUs.
32 bit EFLAGS
3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
┌─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┬─┐
│ │ │ │ │ │ │ │ │ │ │I│V│V│A│V│R│ │N│I O│O│D│I│T│S│Z│ │A│ │P│ │C│
│0│0│0│0│0│0│0│0│0│0│D│I│I│C│M│F│0│F│P L│F│F│F│F│F│0│0│F│0│F│1│F│
│ │ │ │ │ │ │ │ │ │ │ │P│F│ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │
└─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┴─┘
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 1 0 0 1 0 0 0 1 1 0
ID Identification flag (bit 21).
VIP Virtual interrupt pending (bit 20).
VIF Virtual interrupt flag (bit 19).
AC Alignment check (bit 18).
VM Virtual 8086 mode (bit 17).
RF Resume flag (bit 16).
NF Nested task flag (bit 14).
IOPL Input/Output privilege level (bits 13-12).
IF Interrupt enable flag (bit 9).
[Protected mode]
Intel 80286 and higher CPUs have two modes of operation: Real Mode
and Protected Mode.
In Real Mode, the {CPU} behaves essentially like an Intel 8086 CPU.
In Real Mode, address space is limited to 1 Megabyte and only one
task can be executed at a time. No protection is available.
DOS runs in Real mode.
Protected mode accesses up to 4 Gigabytes of memory (for 80386
and higher CPUs), multitasking, I/O privilege levels, and
protection. Protected Mode also has virtual 8086 mode to
emulate multiple 8086 machines running simultaneously.
OS/2 and Windows NT operate in protected mode only.
[Prefetch queue]
While the Intel 80x86 CPU is executing one instruction, it
can fetch subsequent instruction and store them in a queue,
to reduce overall execution time. The depth of this prefetch
queue varies from processor to processor. Even within the same
family, the 80386SX and DX prefetch queues are not the same size.
[DMA]
Direct Memory Access (DMA) is the direct transfer of data to or
from a peripheral device such as a hard disk drive with no
intervention from the CPU.
A DMA controller, when programmed, takes care of all DMA
transfer issues, such as DMA timing, number of bytes to transfer etc.
[Interrupt]
An interrupt is a signal that stops what the CPU is currently
doing, allowing the CPU to perform a higher priority task. An
interrupt is usually generated by a peripheral device demanding
attention. After the interrupt is serviced, the suspended task
is resumed at the point it was stopped.
[RTC]
The Real Time Clock (RTC) is found in all IBM AT-compatible
computers. It provides a separate clock source, independent
of the CPU clock speed, for updating the system date and time.
This clock source can also be used as an alarm.
[CMOS]
Complimentary Metal Oxide Semiconductor (CMOS) is a method of
fabricating integrated circuits (ICs). It is more frequently
used to specify an IC that has been produced by this method.
All CMOS ICs consume very little energy.
The CMOS RAM in IBM AT-compatible systems stores vital
system configuration data. The CMOS RAM is battery backed -
its content remains intact even when the system is switched off.
[EISA]
Extended Industry Standard Architecture (EISA) is a 32-bit
bus standard that enhances the existing 16-bit ISA bus.
EISA also allows level-triggered interrupts, so the same
interrupt can be shared by more than one device.
[PCI]
Peripheral Component Interconnect (PCI) is a popular local bus
standard. A local bus allows peripherals like the display
controller or disk controller to access the CPU bus directly,
permitting much faster operation than the traditional ISA
(Industry Standard Architecture) bus.
[PCMCIA]
Personal Computer Memory Card International Association (PCMCIA)
developed and maintains a standard for credit-card-sized
PC peripherals devices, called PC Cards.
PC Cards, can include I/O controllers, memory, and mass storage
devices. PC Cards are mostly used in AT-compatible notebook
computers. A major advantage is the PC Card size and portability.
[Plug&Play]
Plug-and-play is a new computer industry standard that permits a
computer to automatically configure system resources, foregoing the
necessity for hardware switches and jumpers.
[Cache]
Caching speeds access to information in a slower device by
storing a part of the slow devices information in a much
faster device.
For example, ISA system memory uses DRAMs (Dynamic Random
Access Memory) with typical access times of 60 to 70 nanoseconds.
However, if most memory accesses are to a 64 KB block of
system DRAM memory, the data in that 64 KB of DRAM can be
copied to cache memory.
Cache memory uses SRAM (Static Random Access Memory) with
typical access time of 12 to 14 nanoseconds.
As long as the 64 KB block of data is not modified, the
CPU can access this data from fast cache memory, permitting
a significant boost in performance.
[Parity]
Parity of a block of data storage in memory is the sum of all
bits set in the unit of memory. It is either odd or even.
In even parity,, the number of bits set to 1 must be odd. If
it is not, the data is in error.
Computer memory is organized in bytes (collection of eight
bits). The odd or even parity is maintained by adding a bit,
called the parity bit. This bit is made 0 or 1 by the parity
generation circuitry in such a way that the sum of all set
bits including the parity bit is always kept even or odd.
[Help on help]
There is no help on help.