PC Media 12/PC MEDIA CD12.iso/util/st/st.doc

Text File | 1994-03-06 | 49KB | 1,181 lines

                               SCREEN Thief

                    The Ultimate Screen Capture System

                   Copyright 1993-1994 Nildram Software

                            All Rights Reserved

                 SCREEN Thief was written by Jim Hoggarth



Address:        Nildram Software
                82 Akeman Street
                Tring
                Herts  HP23 6AF
                United Kingdom

Telephone:      [phone]

Fax:            [phone]

Internet:    [e-mail]
        [e-mail]
        [e-mail]

CIS:        GO UKSHARE, Section 10

FidoNet:    2:257/112 (Address messages to ADRIAN MARDLIN)

BBS:        [phone]

SCREEN Thief is a trademark of Nildram Software.

All trademarks and registered trademarks mentioned in this
document are acknowledged.

                              INTRODUCTION


Overview

SCREEN Thief has been designed to solve a range of problems and
annoyances found with other screen grabbing programs. Many
examples exist, often bundled with a graphic manipulation tool
or paint package but sometimes marketed separately. We reckon
that SCREEN Thief succeeds where the rest fail.

Specific problems that have been solved include loss of colour
attribute information and corrupt palettes plus the awareness of
graphic adapter effects such as horizontal and vertical pixel
panning and split screens. SCREEN Thief easily copes with
non-standard video modes employed by games, such as 320 by 240
pixels in 256 colours. It also takes programmed soft fonts into
full consideration when capturing text mode screens. Indeed, we
believe that whatever the standard VGA graphic adapter is
capable of displaying, SCREEN Thief can capture.

This sophisticated 'total solution' also extends to the hot-key
used to trigger a screen capture. Many programs, particularly
games, prevent capture with lesser grabbing packages because
they steal the keyboard interrupt vector and refuse to pass
interrupts back to previously installed programs. Solutions to
this problem have so far included delayed-action grabbing, which
is inaccurate to say the least and also fails where a program
steals the system timer interrupt used for counting out the
delay period.

SCREEN Thief gets around this major problem by secretly
reprogramming the interrupt hardware to a different set of
vectors. When a program steals the keyboard or timer interrupt
it no longer gets first pick, but a fake hardware interrupt
generated by SCREEN Thief's resident code. This technique works
in all but a few rare instances. Another implication is that,
with some restrictions, screens can also be captured under
Microsoft Windows even though SCREEN Thief is a DOS-hosted
program.

One further positive feature is that SCREEN Thief creates output
files in any of several common image formats (GIF, TIF, PCX or
BMP), as well as text formats, rather than through a proprietary
interim file which requires a second conversion stage before
use. When combined with a host of other configurable options,
intelligent image file naming and an extensive internal help
system, you can see that SCREEN Thief is the ultimate screen
capture package for the professional user.

Finally, through absolute use of machine code and clever memory
optimisations, you will find SCREEN Thief to be one of the most
compact Terminate and Stay Resident (TSR) programs you ever
load. It can use EMS memory, Upper Memory Blocks provided by an
XMS/UMB driver or similar and normal system memory to maximum
effect. Typical system memory use amounts to just over 2K. Even
when loaded on a PC with no EMS or UMB memory, requirements can
be as low as 9K.


System Requirements

SCREEN Thief has a number of important minimum hardware and
software requirements. A VGA graphics adapter, on-board VGA
controller or register-level compatible is essential. SCREEN
Thief cannot work with the MDA, Hercules, CGA or EGA adapters
even though it will successfully capture their equivalent video
modes on the VGA. The host PC needs to be an 80286 or better
based IBM AT or close compatible. A hard disk is not essential
but highly recommended. Finally, MSDOS version 3.10 or higher is
essential.


Support

Full lifetime support is provided to all registered users of
SCREEN Thief direct from Nildram Software. Check the front of
this manual for contact details. You will also be notified of
all major upgrades, and offered them at a special reduced price.
Make sure you return your registration card if you didn't
purchase SCREEN Thief direct from Nildram Software, or you won't
be eligible for support, and we won't be able to tell you about
any upgrades.


Disclaimer

Users of SCREEN Thief must accept this disclaimer of warranty:

"SCREEN Thief IS SUPPLIED AS IS. THE AUTHOR DISCLAIMS ALL
WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION,
THE WARRANTIES OF MERCHANTABILITY AND OF FITNESS FOR ANY
PURPOSE. THE AUTHOR ASSUMES NO LIABILITY FOR DAMAGES, DIRECT OR
CONSEQUENTIAL, WHICH MAY RESULT FROM THE USE OF SCREEN Thief."


The ASP

This program is produced by a member of the Association of
Shareware Professionals (ASP). ASP wants to make sure that the
shareware principle works for you. If you are unable to resolve
a shareware-related problem with an ASP member by contacting the
member directly, ASP may be able to help. The ASP Ombudsman can
help you resolve a dispute or problem with an ASP member, but
does not provide technical support for members' products. Please
write to the ASP Ombudsman at 545 Grover Road, Muskegon, MI
49442, USA or send a Compuserve message via Compuserve mail to
ASP Ombudsman 70007,3536.

                            GETTING STARTED


Installation

To install SCREEN Thief, insert the disk supplied into a drive
and then select that drive by typing "A:" or "B:" as appropriate
followed by <ENTER>. Next, type "INSTALL", press <ENTER> and
follow the on-screen instructions. You will be asked for a
destination drive and path for SCREEN Thief which default to
"C:" and "\ST" respectively. Change these if necessary, although
it will be easier to stay with the defaults as they will be used
in the various examples.


Running SCREEN Thief

To run SCREEN Thief with the default settings, change to the
"\ST" directory and simply type "ST". SCREEN Thief will then be
installed and you can run whatever program you need to grab a
screen from. To actually grab a screen, press the <CTRL>, <ALT>
and <T> keys together and you will hear a clicking noise from
your PC speaker as SCREEN Thief is working. The image file
produced will be in colour GIF format and given a name
consisting of the first 6 letters of the name of the program
currently being run followed by a number, eg, "FILENA01.GIF".
This file will be saved to the current directory but you can
specify a different directory when you run SCREEN Thief as
follows:

ST C:\CAPTURE

This will save all captured image files to the "C:\CAPTURE"
directory.


The Command Line

All of SCREEN Thief's operational characteristics are controlled
by command line parameters, mostly switches. Once installed, all
changes to the way SCREEN Thief operates can only be made via
the command line. All the various command line parameters are
covered in detail in the Reference Section of this manual, but
the more commonly used ones will be covered here. These
parameters are:

/OUTPUT    Sets the Output Image File Format to either GIF, TIFF,
PCX, BMP or one of the text output formats, ASC, TXT or SCR. The
default setting is GIF and the syntax of this switch is /O:TIFF.

/MONO    Enables and disables Mono Translation, ie, producing a
black and white image. The default setting is disabled and the
syntax of this switch is /M+ to enable and /M- to disable.

/UNLOAD    Removes SCREEN Thief from memory. This is the only way
to correctly remove SCREEN Thief from memory; do not use
programs such as MARK and RELEASE. The syntax of this switch is
/U.


Example

To use SCREEN Thief to capture screens and output them in mono
PCX format to a directory called C:\PICTURES, type the following:

ST C:\PICTURES /M+ /O:PCX

Once SCREEN Thief is loaded in this way, you could then, for
example, change the output file format by typing the following
from the \ST Directory:

ST /O:GIF

Each time you make a change, the SCREEN Thief window will pop up
showing the new setup.


The SCREENTHIEF Environment Variable

If you regularly use a particular setup for SCREEN Thief that is
not the same as the default setup, you can avoid having to type
all the command line switches each time, as in the example
above, by using an environment variable. This is a string
containing the required command line parameters that is placed
in the AUTOEXEC.BAT file using the DOS SET command as in the
example below:

SET SCREENTHIEF=C:\PICTURES /M+ /O:PCX

This will then use these parameters every time SCREEN Thief is
run, overriding the defaults so that you only need to type "ST"
to access your most used setup. The command line parameters will
override the environment variable so you can still run SCREEN
Thief differently as necessary.


The SCREEN Thief Configuration File

Although the Environment Variable allows you to set SCREEN Thief
up to a certain extent, you may have various configurations for
specific tasks that you would like to automate. This is possible
using the Configuration File. Any parameters on the command line
(or within the SCREENTHIEF environment setting) which do not
follow a switch character will first be compared against the
Configuration File. This is a simple text file such as can be
created with any text editor or word processor in ascii mode. It
must be called CONFIG.ST and exist in the same directory as the
ST executable file.

Configuration entries are implemented in the same way as the
environment string, but each is preceded with a unique name.
Each configuration must start on a new line, with a maximum line
length of 255 characters including the config name. Any
characters beyond this are truncated. For example:

REVIEWS=N:\PUB\REVIEWS\PCX /RGB+ /M- /O:PCX /K:50 /SH:OFF
BOOKS=N:\PUB\BOOKS\GRABS /RGB- /MONO /O:GIF /K:01 /SH:CL

This allows easy switching between different configurations
based solely on a customer, project or user name. However, note
that any option changed in one configuration will need to be
changed in every other configuration unless valid for all cases.

Configuration names are allowed within the environment string
and on the command line. Multiple configuration names are also
permitted, but nesting is not. This means that a config entry
cannot name another within its command line. Configurations can
also be used in isolation or in addition to other command line
switches.

If no matching entry is found within the CONFIG.ST file SCREEN
Thief will then attempt to use it as an image file directory
name and check its validity accordingly.


The Help System

SCREEN Thief has an extensive help system that may be used in
one of two ways. Firstly, if an error occurs, the help system
will be automatically started, the error message displayed and
the correct subject highlighted. Simply press the right-arrow
key to expand the help screen for further information. Please
note that not all errors will produce this automatic help; some,
such as "Directory Non Existent" that are self-explanatory, just
bring up an error message and quit the program.

Secondly, the help system may be started without actually
loading SCREEN Thief, by typing "ST /?" from the "\ST"
directory. You will see the SCREEN Thief window on the screen at
this point containing a list of help subjects. Select the
subject you require using the up-arrow and down-arrow keys and
then press the right-arrow key to expand the help screen. Where
applicable, use the up-arrow and down-arrow or the page-up and
page-down keys to view the text in the expanded help screen. The
left-arrow key will return you to the list of help subjects.


System Crashes

If SCREEN Thief crashes your machine when run, or when you
attempt to grab a screen, you should first suspect the base
interrupt vector setting (see /INTERRUPT for more details). This
is by far the most likely cause of a system crash, and you can
work around it by specifying a different base interrupt vector
by using the /INTERRUPT command line switch.

The second most likely cause of a system crash is if a program
interferes with SCREEN Thief's buffers. To work around this
problem, use the /BUFFERS switch to force SCREEN Thief to use a
specific area of memory for its buffer storage.REFERENCE


Output Image File Naming

SCREEN Thief attempts to intelligently name the Output Image
File by extracting the executable name of the underlying
program, from which the first six characters are taken. To this
is added a two digit number from 01 through to 99. The extension
used depends on the output format, such as GIF, BMP etc. The
directory into which the image is saved depends on the path name
given at the command line when SCREEN Thief was installed.

However, if SCREEN Thief detects that you are at the command
line prompt, the file name SCREEN is used.  SCREEN Thief always
fills any gaps, creating SCREEN01.* first even when SCREEN02.*
and so on exist. If you capture screens under Windows (other
than in a DOS box under 386 Enhanced Mode), the file will be
named WIN with the same two digit number added to give WIN01.*,
WIN02.* and so on.

The only exception is where Numeric Naming is enabled with the
/NUMERIC switch. All Image files are then named from 00000001.*
through to 99999999.*.


Use Under Microsoft Windows

SCREEN Thief will successfully work under MS Windows even though
it is a DOS-hosted application, with certain exceptions. Windows
versions prior to 3.0 are not supported, nor is Real Mode. The
two distinct Standard and 386 Enhanced modes are also handled
quite differently.

Standard Mode

In order to capture the complete screen (including active menus,
the cursor etc.), you must run Windows in Standard Mode with the
WIN /S command. The same capture hot-key works as before,
although you may wish to choose a hot-key which does not
conflict with any Windows application accelerator keys. Also be
cautious about Super VGA cards which are supplied with Windows
drivers but which SCREEN Thief does not yet support in high
resolution modes. One further restriction is that no changes can
be made to SCREEN Thief from the command line (through DOSPRMPT)
that require major changes to the SCREEN Thief video, control
and output encoder buffers. An error will be shown if this is
the case.

386 Enhanced Mode

If you attempt to run Windows in 386 Enhanced Mode with SCREEN
Thief resident, a message will appear after the Windows logo
asking you to use the /S switch or to remove SCREEN Thief from
memory. Once up and running in 386 Mode, SCREEN Thief can be run
again from within a DOS box. However, the capture hot-key is
only active when the DOS window has focus, and then only the
contents of the window are captured. It is handled as a virtual
Standard VGA adapter and extended modes when the DOS box is full
screen are not fully supported.


Interpreting The Audio Signals

When capturing a screen, SCREEN Thief lets you know about its
progress by means of a series of clicks over the speaker. It
follows these with a single high-pitched tone to indicate that
it has successfully completed the capture. An error is indicated
by a series of two tones, the first one higher than the second.

The clicks can be disabled using the /CLICKS- switch. In this
case, SCREEN Thief gives a single mid-tone beep instead of the
clicks. The final high-pitched beep or two-tone error signal
will still be present at the end of a capture.


SuperVGA Adapter Support

Although SCREEN Thief is primarily designed for use with the
standard VGA graphics card, continual development means that
support for certain SuperVGA (SVGA) cards is already present in
this version.

In any case, SCREEN Thief should be able to capture all but the
odd few extended text mode screens provided by the majority of
SVGA cards, such as 132 columns by 25, 30, 43 or 60 rows. The
only occasions where this will fail are where a text mode
character cell is other than the standard eight or nine pixels
wide. Nildram Software are already aware that some cards use
character cells seven or ten pixels wide. Support for these
modes may be available in a future version, although this is not
a priority task.

Specific graphics mode support for extended SVGA systems
includes:

The Trident family of video adapters (the most popular of which
use the TVGA8900 and TVGA9000 chip sets).

Paradise and Western Digital cards which use the PVGA1A chip.

SVGA cards based on the Cirrus Logic CL-GD5422 single chip
controller.

Oak Technology cards using the OTI-037C (256K) and OTI-077
(1024K) chips.

S3 cards using the base level 86c911 chip variant.

Tseng cards using the ET4000 chip.

These SVGA adapters have been tested extensively over a wide
range of supporting software, native video modes and even
product specific video drivers such as for Microsoft Windows.

Although we cannot guarantee a successful screen capture every
time on these SVGA cards, users with these named products or
graphic cards which use the same chip sets should find that even
the highest resolution screens can be captured perfectly.
On-going development will undoubtedly add many more popular SVGA
card types to this list.

                         COMMAND LINE SWITCHES


Syntax Rules

All command line switches must follow the same format. Both the
usual '/' and UNIX-style '-' switch characters are recognised,
although the first is preferred under DOS. The '-' character may
also confuse those switches which take an optional plus or minus
sign to enable or disable features.

This is followed by the switch name in lower or upper case or a
combination of both. The full switch may be given or a shortened
version. The absolute minimum is enough characters to uniquely
distinguish each switch. The present design of SCREEN Thief is
such that only the first character of each switch name is
required in all instances. For example, /EGAFONTS, /EGA and /E
are all equivalent.

Where a switch requires a numeric, character or string value,
the switch name and this additional parameter value must be
separated by a colon character (:) or optionally the equals
character (=). As with the switch names, any string parameter
need only be so long as to be recognisable, as in /VIDEO:TRID
for the Trident video adapter driver.

Where a switch takes a plus/minus sign for enabling/disabling a
feature, no colon (:) or equals (=) separator is required. If
the switch name alone is given, or followed by the optional plus
(+) sign, the feature is enabled. Disabling the feature requires
the same switch name followed by a minus sign (-). No white
space is allowed between the name and the plus/minus.

Any complete switch sequence must then be followed by either a
space, end of line or another switch character. It can be seen
that the following are all equivalent. It is left to the user to
choose their particular style preference:

/INT:A0
-i=A0
/INTERRUPT=a0
-Inter:a0


Switch Summary

/BLINKATTR:string    Select the Attribute for Blinking Pixels
/BUFFERS:string         Select the Control Buffer Area
/CLICKS[+|-]            Disable the Scan Line Clicks
/COMPRESSION[+|-]       Choose a Compressed Image File Format
/COREDUMP[+|-]          Dump the Control Core to File
/EGAFONTS[+|-]          Use EGA Fonts for Text Mode Captures
/FULLFRAME[+|-]         Generate True Raster Output Images
/INTERRUPT:hex          Select the PIC Interrupt Base
/KEY:char|hex           Set the Screen Capture Hot-Key
/LZW:num                Choose the LZW Compression Level
/MONO[+|-]              Mono Translate for Text Mode Captures
/NUMERIC[+|-]           Select Numeric Output Image File Naming
/OUTPUT:string          Specify the Output Image File Format
/REGISTER               Register the TEST DRIVE version
/RGB[+|-]               Quick Support for 24-bit RGB Output
/RTCREFRESH[+|-]        Disable Real Time Clock Refresh
/SHIFTS:string          Set the Screen Capture Hot-Key Shifts
/STREAMSIZE:num         Set the Output Image Stream Size
/UNLOAD                 Unload SCREEN Thief from Memory
/VIDEO:string           Override the VGA Chip Set
/WIDTH:num              Set the Maximum Screen Capture Width
/?                      Display the Help Screens


Default Settings

Running SCREEN Thief without any command line or environment
options results in the following default settings:

Blink Attribute         HIGH
Buffers                 All searched
Clicks                  ON
Compression             ON
Core Dump               OFF
EGA Fonts               OFF
Full Frame              OFF
Hot Key                 <ALT><CTRL><T>
Interrupt Base          D8 hex
LZW Compress Level      4
Mono Translate          OFF
Numeric Naming          OFF
Output Format           GIF
Output Directory        Current
RGB                     OFF
RTC Refresh             ON
Stream Size             768 bytes
Max Width               1,188 pixels


/BLINKATTR

Syntax:         /BLINKATTR:string

This switch controls how the attribute associated with a
blinking pixel in 16-colour graphics mode is interpreted.  It
takes one of two string values, either /BLINKATTR:HIGH or
/BLINKATTR:LOW.

The VGA controller creates a blinking effect by toggling the
high bit of the pixel's attribute. This alternates between two
colours in the low and high halves of the 16-colour palette.
Normally the palette is designed so that the high entry is
visible or intense, and the low entry is black or at normal
intensity. This is also the default assumed by SCREEN Thief.

In some instances the palette is programmed in the opposite
sense and selecting the attribute from the top half of the
palette will cause the blinking pixels to look black (or
invisible relative to the surrounding pixels) in the created
image.  Use /BLINKATTR:LOW to force attribute selection from the
lower half of the palette.


/BUFFERS

Syntax:        /BUFFERS:string

This switch defines the memory area used to store the SCREEN
Thief video driver, output image encoder and control buffers. It
accepts the string values UMB, EMS, HIGH and LOW.  These
correspond to the following memory areas:

UMB     Upper Memory Blocks as provided by HIMEM.SYS plus
EMM386.EXE or any equivalent UMB provider such as UMB_DRV.SYS.
SCREEN Thief does not use protected mode memory over 1MB, only
free UMB space between 640K and 1MB.

EMS    Memory pages provided by a hardware or software LIM/EMS
3.20+ driver. As the minimum granularity provided by EMS pages
is 16K many of the switches which limit memory use are obsolete.
To obtain a report on EMS page usage run the external MS-DOS
command MEM /D. The pages allocated to ST will be shown as a
hexadecimal byte count, but only for EMS drivers version 4.00 or
higher.

HIGH    Normal DOS memory allocated at the end of the DOS control
block chain. This differs from the normal practice of memory
allocation from low memory and upwards. The benefit is that
previous buffers can be freed and reallocated without leaving
holes in the memory chain. This method may fail when badly
written programs incorrectly make the  assumption that all
memory from their base segment up to the end of system RAM is
available for use.

LOW     Normal DOS memory allocated from the lowest empty area and
up. Any subsequent changes to the buffer setting could cause
holes to appear in the memory allocation chain, especially where
other resident programs are loaded after SCREEN Thief. This type
of allocation is only recommended when HIGH fails due to a
program overwriting memory space that is not allocated to it.

No provision is made for use of the HMA (High Memory Area).  It
is assumed that the DOS kernel is loaded high, and the HMA is
ignored even if free. Note that SCREEN Thief does not attempt to
split its buffers between different areas, nor can it use any
non-contiguous blocks in the same area.

Once loaded, if a command line switch requires one of the
encoder, video or control buffers to be replaced or resized, all
are dumped and reloaded accordingly. Unless overruled by the
/BUFFERS switch, SCREEN Thief will always re-use the same buffer
areas.  This could result in the buffers being discarded and not
reloaded if this new size requirement no longer fits within
available memory. Capturing a screen will immediately fail with
an error beep (Last Error will show Control Buffers Absent). You
should rerun SCREEN Thief with a different and valid /BUFFERS
switch setting.


/CLICKS

Syntax:        /CLICKS[+|-]

This switch enables and disables the audible scan line clicks.
Use /CL on its own or /CL+  to enable, /CL- to disable. The
default setting is enabled or ON.

SCREEN Thief indicates the progress of a capture through the
PC's loudspeaker. As each output image scan line is sent to be
encoded a click is generated. This lets the user know the speed
at which the capture is progressing and that all is well. If
required this clicking or rasping noise can be disabled, to be
replaced by one mid-tone beep at the start of each image. In all
cases the final single beep indicating success or the two-tone
beep warning of an error will still be heard.


/COMPRESSION

Syntax:        /COMPRESSION[+|-]

This switch enables and disables Output Image File Compression.
Use /COM on its own or /COM+ to enable, /COM- to disable. The
default setting is enabled or ON.

The TIFF and BMP outputs cater for both compressed and standard
image data representations, and this switch allows you to choose
whether compression is applied. TIFF files use LZW compression
and thus the /LZW switch will also affect the output image file.
BMP files use an RLE method of compression which applies only to
4-bit and 8-bit image data.

Note that this switch has no effect on GIF or PCX output image
formats as these use compression by default. Nor does it apply
to any 'non-image' output formats such as TXT and SCR.


/COREDUMP

Syntax:        /COREDUMP[+|-]

This switch enables and disables the Core Dump feature. Use /COR
on its own or /COR+ to enable, /COR- to disable. The default
setting is disabled or OFF.

The Core Dump facility is provided for post-mortem debugging of
SCREEN Thief problems or incompatibilities. If a screen cannot
be successfully captured, either because the output image is
corrupt, does not represent the actual screen displayed or
because SCREEN Thief refuses to capture a screen for any reason,
the Core Dump can be enabled and a second attempt made at
capturing the same screen.

Any output image file and the generated core dump debug file can
be analysed by Nildram Software and a solution sought. The
generated file is of a binary type and unsuitable for diagnostic
purposes of the user. The file is always named COREDUMP.ST and
saved in the same directory as the captured screen image file.
Normally you can ignore this feature unless requested by Nildram
Software Technical Support.


/EGAFONTS

Syntax:        /EGAFONTS[+|-]

This switch enables and disables the EGA Fonts feature. Use /E
on its own or /E+ to enable, /E- to disable. The default setting
is disabled or OFF.

When enabled SCREEN Thief will ignore the video RAM font data
for text modes and use the standard EGA 8 x 14 ROM font in
generating the output image. This feature is required where 80
col by 25 row screens (standard DOS text mode) are to be
redisplayed as part of an animation or tutorial. Normally SCREEN
Thief will generate any images at 720 x 400 pixels in accordance
with the 9 x 16 VGA font which is unsuitable for playback in
standard graphic modes. Using the EGA font option produces
images at 640 x 350 pixel resolution and these can be
redisplayed in the EGA/VGA's standard mode 10h.

Programs which use advanced VGA features such as split screens
or pixel panning will probably result in corrupt images when the
EGA Fonts option is used.


/FULLFRAME

Syntax:        /FULLFRAME[+|-]

This switch enables or disables the Full Frame feature for 256
colour graphics modes. Use /F on its own or /F+ to enable, /F-
to disable. The default setting is disabled or OFF.

When displaying 200-line (and non-standard 240-line) 256 colour
modes, the VGA controller in fact displays a 400-line raster by
regarding each pixel as a 2-cell high matrix. Ordinarily SCREEN
Thief will compensate for this and generate output with no scan
line duplication. However, when a split screen is in effect and
the line compare register has been programmed with an even scan
line number, the VGA causes a split between two duplicate lines
resulting in an extra half scan line in each split area.  It is
impossible to emulate this unless the true, full frame of lines
is sent to the output encoder. The /FULLFRAME switch will force
this option on, and in order to retain the aspect ratio, pixels
within each scan line are also duplicated. Thus 320 by 200 mode
generates a 640 by 400 output image.


/INTERRUPT

Syntax:        /INTERRUPT:hex

This switch selects the base interrupt vector. It takes a
hexadecimal number in the range 78h through to E0h. The default
is D8h. SCREEN Thief requires a consecutive run of eight unused
interrupt vectors, and it is essential that those chosen do not
conflict with other software packages or hardware devices. The
allowed range is deliberately limited to avoid those vectors
always or likely to be used in all PC installations.

Normally you will not come across conflicts unless specialist
hardware is being used. Software packages rarely use interrupts
in this region, and if they do they should have the fact
documented and the ability to change as required to avoid
conflicts. If you ever suffer from system crashes or hardware
lock-ups, suspect this base interrupt value first. If in any
doubt try booting your PC from minimal system floppy disk, and
perhaps removing or disabling any expansion cards suspected of
being in conflict.

Note that the /INTERRUPT switch is only concerned with initial
installation. Any further use of this switch is considered an
error. If you wish to change the interrupt base, /UNLOAD SCREEN
Thief and re-install with the new interrupt base value.


/KEY

Syntax:        /KEY:[char|hex|string]

This switch selects the character, function or other key used in
combination with the shift keys (selected with the /SHIFTS
switch) which make up the screen capture hot-key. It accepts
single character values for the alphanumeric keys found on the
standard QWERTY keyboard layout, string values covering the
twelve possible function keys and hexadecimal values for any
remaining keys and non-QWERTY keyboard types (refer to the
Keyboard Scan Codes section elsewhere).

/KEY:char    Single characters in the range A through Z and 0
through 9. The default is set as T.

/KEY:str    The function key names F1 through F12 only.

/KEY:hex    A two digit hexadecimal number which is a valid PC
keyboard scancode, other than 1D, 2A, 36 and 38 which are the
codes for the four shift keys. A program, "SCANCODE.COM" is
provided which will tell you the scan code for each key on your
keyboard. Simply run SCANCODE and then press the key you
require. When you have finished, you should press <ENTER> twice
to exit SCANCODE.

Upper or lower case characters can be used.


/LZW

Syntax:        /LZW:number

This switch selects the size of code look-up table needed by the
LZW data compression routine used by the GIF Output Image format
and by the TIFF Output Image format if compression is enabled.
It accepts a single character numeric value in the range 1
through 8, where 1 is the smallest and 8 is the largest and
maximum size of table.

This switch affects the SCREEN Thief memory requirements, speed
at which the GIF image is saved to disk and the size of the
final image file. A value of 1 allocates a small table which
uses little memory, is quickly filled and often cleared for
reuse. Image file size is at its largest, often by a factor of
four or five. Progressively larger values up to the maximum of 8
increase memory requirements and the time taken to generate the
image file, but the resultant file size is much reduced. The
default value is 4.


/MONO

Syntax:        /MONO[+|-]

This switch enables and disables Mono Translation. Use /M on its
own or /M+ to enable, /M- to disable. The default is disabled or
OFF.

When enabled SCREEN Thief ignores all attribute information
within text mode. Output is in two colour, black on white
(although the image written to file may be in 4- or 16-colour
format, using just the colours white and black). Black pixels
are those where the Font data bits are set. White pixels are
those where the font data bits are cleared (zero). This is the
opposite of any displayed image (regardless of colour content)
where the assumption is white on black.

This feature is specifically designed to capture screens for use
in single colour printing, such as manuals and user guides,
where four or spot colour printing is not available or desired.
Note that at present no account is taken of any inverse
attributes.


/NUMERIC

Syntax:        /NUMERIC[+|-]

This switch enables and disables Numeric Output File Naming. Use
/N on its own or /N+ to enable, /N- to disable. The default is
disabled or OFF.

Normally the output image file name is constructed from two
parts. SCREEN Thief attempts to extract the executable file name
from the underlying application, using at most six characters
from this name. To this is appended a consecutive number from 01
through 99.

Enabling the Numeric Output dispenses with the executable file
name part and generates files from 00000001 and up. The
extension used always depends on the output image format (GIF,
PCX etc).


/OUTPUT

Syntax:        /OUTPUT:string

This switch selects the output image format encoder to be used
for all screen capture. It takes a string value which names the
format. Currently supported formats are GIF, PCX, TIFF, BMP, ASC
(ascii), TXT (text) and SCR (screen).

Note that for all output formats, when capturing a monochrome
image (as opposed to a 2-colour image), SCREEN Thief will always
produce a 16-colour image file. Monochrome modes require three
colours anyway for black, white and intense white, and as some
formats do not support 4-colour images, they are simply promoted
to 16-colour by default.

GIF    CompuServe GIF format is a highly compact image format which
uses LZW compression as standard. It has undergone few
specification changes over the years and as such is an extremely
stable and well defined format. All of the major paint, DTP and
image conversion programs can use this format successfully. GIF
supports images at resolutions of 2, 4, 16 and 256 colours. For
15/16/24-bit RGB images another format is required, such as PCX
or TIFF. Use the /LZW switch to modify the size of the look-up
table used by the compressor. GIF format also overrules the
/COMPRESS switch.

PCX    ZSoft PCX format is one of the industry standard formats,
although there can be problems with file compatibility between
applications. SCREEN Thief always generates Type 5 PCX files
regardless of colour content, as most programs now seem to work
with that type. The PCX format can support images at resolutions
of 2, 4, 16 and 256 colours, plus 24-bit for HiColor and True
Color images. SCREEN Thief, however, will not use the 4-colour
format because of possible compatibility problems and will
always promote 4-colour images to 16-colour. The PCX format
incorporates RLE image compression as standard. This is not
affected by the /LZW or /COMPRESSION switches.

TIFF    Aldus/Microsoft TIFF format is another standard image
format popular in the Desktop Publishing, printing and document
processing industries. It directly supports all the colour
resolutions that SCREEN Thief also handles and as such is a good
format for general use. The TIFF specification allows for a
number of compression formats and SCREEN Thief will generate
TIFF files using the LZW algorithm if compression is enabled
with the /COMPRESSION:ON switch. The /LZW switch may also be
used to modify the size of the look-up table used by the
compressor. However, as SCREEN Thief generates TIFF image
'strips' at the recommended size of 8K, and as the standard
requires that each strip starts with a empty LZW look-up table,
TIFF file compression will rarely match the best results
obtained from the GIF format. It may be found that the /LZW
switch has little effect on output image size, particularly with
full colour photo-realistic images.

BMP    Microsoft Windows BMP format is the best choice where the
output image will ultimately be used in the Windows environment.
It directly supports all the colour resolutions that SCREEN
Thief also handles. Output is always in Device Independent
Bitmap (DIB) format as used by Windows 3.0 and higher with
optional RLE encoding when enabled with the /COMPRESSION:ON
switch. As the BMP type does not support 4-colour images these
will be automatically promoted to 16-colours, although the
majority of BMP file viewers and tools will report these as
being only 4-colour. NOTE: If the BMP files are intended for
further editing within the Windows Paintbrush program, set RLE
compression off with /COMPRESSION:OFF. Paintbrush does not
understand the RLE format.

ASC    This is one of the three character based output formats. It
only applies to text mode screens and an error will be issued if
any attempt is made to capture a graphics screen. Output
comprises text characters extracted from the display, without
attributes, and encompassing the full IBM/ASCII character set,
that is in the range 0 through FF. The ASC format also adds an
end of line (CR/LF) to each character row and removes all
trailing space characters. Other than this non-printable
characters remain within the output. Use the TXT format to
remove all non-printing characters from the text. Use the SCR
format for capturing the complete screen, including attribute
information. Note that although any byte panning programmed into
the VGA adaptor can be accounted for in the output, horizontal
and vertical pixel panning cannot be handled in any of the three
character based output formats. Also note that split screen
effects are ignored.

TXT    The TXT output format is functionally the same as the ASC
format (see above). However, all of the non-printable characters
are replaced with space characters. A TXT file consists of just
the ASCII character codes 20h through 7Eh.

SCR    The SCR output format is simply a data dump of the visible
screen character and attribute data. No additional information
is added such as line breaks, and is not a directly 'printable'
format. Each screen character occupies two bytes in the output
file, the character code followed by its associated attribute
byte. Thus an 80 x 25 screen generates a 4,000 byte file. The
first character and attribute pair in the file comes from the
top left origin of the screen.


/REGISTER

Syntax:        /REGISTER

This switch is relevant to the TEST DRIVE version of SCREEN
Thief only. When used a registration info screen is displayed.
You also have the option to print out a registration form for
completion and signing, to be accompanied with the registration
payment.

Note that any other command line switches or parameters will be
ignored if this switch is present (although if syntax errors are
encountered in any of the parameters preceding the /REGISTER
switch, an error message will be displayed and the help system
will probably appear). No configuration changes will be made to
a currently installed copy of SCREEN Thief, nor will SCREEN
Thief install itself in memory if not yet present.


/RGB

Syntax:        /RGB[+|-]

This switch acts as a quick method of trebling the Max Width
setting, rather than changing through the /WIDTH switch. Use
/RGB on its own or /RGB+ to enable, /RGB- to disable. The
default is disabled or OFF.

Enabling this feature automatically reserves enough scan line
buffer space to cope with up to 24-bit RGB image data at the
same horizontal pixel resolution as the Max Width setting.

Allowing for the /WIDTH default and with /RGB+ this is enough
for capturing images up to 1024 pixels wide in 16.8 million
colours.


/RTCREFRESH

Syntax:        /RTCREFRESH[+|-]

This switch enables and disables DOS clock refresh from the RTC.
The default is enabled or ON. Refer to the Switch Syntax help
screen for full syntax details.

In order that any screen image remains stable during a capture,
SCREEN Thief disables the timer and vertical sync interrupts for
the foreground process. As this would cause the DOS clock to
lose several seconds at every capture, SCREEN Thief will
normally reset the DOS time to the Real Time Clock before
handing the interrupts back.

In a few rare cases this can cause the foreground process to
lose track of its own internal timing. This may result in a
short pause or a total lock up. Disabling DOS time refresh from
the RTC clock may cure these kind of symptoms following what
appears to be a successful capture.


/SHIFTS

Syntax:        /SHIFTS:string

This switch selects the shift keys used in combination with the
character key (selected with the /KEY switch) which make up the
screen capture hot-key. It accepts up to four character values
which represent the following shift keys:

A = <ALT>
C = <CTRL>
L = <LEFT SHIFT>
R = <RIGHT SHIFT>

Characters can be either upper or lower case. The default is AC
for <ALT><CTRL>. This switch will optionally accept the two
string values OFF and NONE, leaving the shift keys out of the
hot-key combination. This is useful for capturing screens from
the likes of games where the <ALT>, <SHIFT> and <CTRL> keys are
used for program features such as firing and jumping. Use:

/SHIFTS:NONE  or  /SHIFTS:OFF

Be careful with this feature. It is possible to set the hot-key
as a single alphabetic character, affecting command line entry
to the point where you can't run ST for a new /SHIFTS value.


/STREAMSIZE

Syntax:        /STREAMSIZE:number

This switch determines the space allocated for file output image
streaming. It takes a numeric value in the range 128 to 32768.
The default is 768 bytes.

This switch is useful when capturing directly to a floppy disk,
as you can limit the number of disk writes required to save the
whole image file. Alternatively the stream can be reduced in
size in order to squeeze SCREEN Thief into as small a memory
area as possible.

Note that this switch has no effect on the GIF output image
format, as this has a natural block size of 256 bytes.


/UNLOAD

Syntax:        /UNLOAD

This switch removes SCREEN Thief from memory and releases any
memory resources used by it. This is only possible if the
interrupt vectors used by SCREEN Thief still point to its
resident code. Normally this will be where SCREEN Thief was the
last TSR program loaded.

SCREEN Thief is fully compliant with AMIS 3.4 (Alternate
Multiplex Interrupt Specification). Any TSRs supporting the same
specification are capable of being removed from memory whatever
the loading order, on condition that non-compliant TSRs do not
break the loading chain.

Note that any other command line switches or parameters will be
ignored if this switch is present, although if syntax errors are
encountered in any of the parameters preceding the /UNLOAD
switch, an error message will be displayed and the help system
will probably appear.

Users are advised NOT to use TSR release programs such as MARK
and RELEASE. Only SCREEN Thief can remove itself from memory
correctly.


/VIDEO

Syntax:        /VIDEO:string

This switch overrides the normal SuperVGA detection routines. If
SCREEN Thief fails to detect one of the supported SVGA chip sets
and you know your video card uses one, you may force SCREEN
Thief to load the required driver. It is also of use where the
automatic detection routines adversely affect an unrecognised
chip set due to the register-level accesses it makes. In this
case you can force SCREEN Thief to load the Standard VGA driver.

The switch accepts a string value naming a particular chip set.

VGA    The standard IBM register-level compatible VGA card. This
driver is fully tested and should be capable of determining and
handling any mode programmed into the VGA card, even
non-standard modes. It will also suffice for the majority of
SVGA cards equipped with 256K of video RAM. Even 800 by 600
16-colour modes should be captured successfully.

ET4000    SCREEN Thief's Tseng SVGA card driver is ET4000 chip
specific. It has been thoroughly tested for all the documented
ET4000 SVGA modes. The ET3000 chip will not be detected or
handle correctly.

GD5422    SVGA cards based on the Cirrus Logic CL-GD5422 single
chip controller are becoming increasingly common. It
incorporates fast BitBlt support in hardware and an in-built
RAMDAC for 15/16 bit HiColor and 24-bit TrueColor modes. SCREEN
Thief has been tested with all documented video modes supported
by this chip.

OAK    The SCREEN Thief Oak Technology Inc. driver is fully tested
with the OTI-037C (256K) and OTI-077 (1024K) chips in all
possible modes other than, at present, support for 32K colour
modes with a Sierra RAMDAC. We see no reason why SCREEN Thief
will not work with the OTI-057 and OTI-067 chips.

PARADISE    The SCREEN Thief PARADISE/Western Digital driver is
fully tested for use with the PVGA1A chip set. It may work
successfully with the later WD90C00 chip (also known as the
PVGA1B), WD90C10 and WD90C11. It's been reported that the
WDxxxxx types create corrupt images sometimes. We assume this is
with interlaced displays and a fix will arrive in due course.
This driver has not been tested with the older and bugged PVGA1
chip.

S3    The SCREEN Thief S3 driver caters for the base level 86c911
chip variant. It has been tested with all of the documented
video modes.

TRIDENT    The TRIDENT chip is popular and found on many cards,
even those manufactured under other names. The most common chip
versions are TVGA-8900B, 8900C and 9000. This SCREEN Thief
driver is fully tested under all these versions and should
detect and work with any remaining versions compatible with the
8900/9000. The only problem that may be encountered is with the
older, and now rare, 8800 chip - particularly the 8800BR variant.


/WIDTH

Syntax:        /WIDTH:number

This switch determines the space allocated for screen image scan
line buffering and encoding. It takes a numeric value in the
range 720 through 4096. The default is 1188 pixels, sufficient
for 1024 pixel wide graphics modes and 132-column text modes at
nine pixels per character cell.

Reducing the maximum scan line width will have a slight effect
on the overall memory requirements of SCREEN Thief, although
capturing the higher resolution screens may fail. This switch is
mainly provided in order to support modes with a greater pixel
resolution than the assumed default maximum. Normally you will
not need to use this switch.


/?

This switch invokes the SCREEN Thief Help System. Note that any
other command line switches or parameters will be ignored if
this switch is present (although if syntax errors are
encountered in any of the parameters preceding the /? switch, an
error message will be displayed and the help system will
probably appear anyway). No configuration changes will be made
to a currently installed copy of SCREEN Thief, nor will SCREEN
Thief install itself in memory if not yet present.