BBSGIF Quick Notes
V 0.9h 28-July-89
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This file contains brief documentation on BBSGIF, an online GIF image view/
capture utility using the 1K-XModem CRC protocol. This document assumes you
are familiar with external protocol modules (such as DSZ.COM by Omen Tech.)
in general, and the Graphics Interchange Format (GIF) as it relates to the
storage of graphics images in files.

This is a BETA release of the program - all known bugs have been removed.
If you find a bug, please report it to me at either of the addresses listed
at the end of this document.

"GIF" and "Graphics Interchange Format" are service marks of CompuServe, Inc.,
an H&R Block company.

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INSTALLING:

BBSGIF should be installed with the comm software you intend to use it
with; i.e., in the same subdirectory. Additionally, you should add one
of the two the following lines to your AUTOEXEC.BAT file:

SET OZPORT=?
or
SET DSZPORT=?

where the question mark is replaced with the number of the comm port to which
your modem is connected. If you also use the DSZ.COM external X/Y/ZModem
protocol module by Omen Technology(tm), you should use the second of the two.
If your modem is connected to an IBM PS/2 on COM 3 or 4, or if your serial
port does not reside at the "standard" base address and/or interrupt request
line for that number port, there are two other environment variables you
need to set:

SET OZBASE=?
SET OZIRQ=?

where the question mark in the OZBASE line is replaced with the _decimal_
base address of your comm port hardware, and the question mark in the OZIRQ
line is replaced with the number of the Int. Request line your port uses.

BBSGIF provides "Super" VGA support for several different types of cards.
However, it cannot detect which type of SVGA card you have beyond that it
supports standard VGA modes. If a VGA card is detected, the software checks
to see if it uses a Tseng Labs chipset and if not assumes "vanilla" VGA. (The
Tseng chipset is used on Orchid, STB, Genoa and other popular SVGA cards.)
Most GIF images available on CIS and the BBS's that were produced on IBM-type
hardware have sizes that match one of the modes available on this chipset.
Other popular chipsets are manufactured by Paradise, Video7, Chips&Tech. and
Trident. These other chipset manufacturers' modes may or may not match up
well to these Tseng mode sizes. The only SVGA mode that all of them share is
a 640x480x256 mode. BBSGIF allows you to tell it which of these other chipset
types your card uses, and then forces all images over 320x200 to use this
640x480 mode. This means that 640x350 images may appear somewhat "squashed"
on these other card types, but allows all images to display normally. (Those
with Tseng Labs chipsets will still have full autodetection in 640x350, 800x600
and 1024x768 modes.) To tell BBSGIF which of these special card types you use,
add the following line to your AUTOEXEC.BAT file:

SET OZVID=?

where the question mark is replaced with:

P - for Paradise chipset cards
V - for Video7 chipset cards
T - for Trident chipset cards
C - for Chips&Technologies chipset cards (both 435 and 441 versions)

----

If you prefer passing such information on the command line rather than as
environment variables, BBSGIF allows it. The following command line
switches can be used:

-C
-B
-A
-I
-V

BBSGIF forces N/8/1 parameters because they are required for the protocol
transfer. The default port is #1 so if your modem is attached to that port
you need _no_ command line parameters or environment variables (other than
the filename command line parameter and possible chipset identifier - see
below.)


RUNNING:

BBSGIF is best used when installed as an external protocol module directly
in your regular comm software (if it supports such setups.) For programs
like ProComm Plus and Boyan, this means directly into the configuration
section of the program. Programs like QModem require you to write a batch
file to handle parameters passing, etc. Follow your comm software's
instructions concerning this type of setup. If your commware only supports
a generic "shell to DOS" capability, you may want to create a batch file to
ease parameters passing. You _must_ pass to BBSGIF a filename for the cap-
tured image file on the command line, just like you do most other ext. proto
modules.

BBSGIF is used in exactly the same way as most other protocol modules. You
simply request a 1K-XModem download of the GIF image file, then invoke BBSGIF
at the same time and in the same manner you would DSZ or other external proto
module. BBSGIF does the rest. You must provide a filename for the captured
image on the command line. You can abort the protocol transfer at any time;
just press [ESC]. All other keys are ignored. When the image transfer is
complete, the program will beep and the image will be left displayed. Press
[Enter] to exit BBSGIF and return to your communications program. If too many
protocol errors occur, or the sending program decides to cancel the transfer,
the image will be aborted and the partial capture file deleted. Remember that
if you sit and look at the image for very long after it has been "painted" on
the screen and the beep signaling end-of-transfer has sounded, any prompt that
may be issued by the BBS software following any normal download will be lost.

BBSGIF currently _only_ supports 1K-XModem CRC as the protocol used in
handling the GIF image stream. Be sure to tell the BBS software to use
1K-XModem (_not_ YModem) to send the file. Other protocols (especially
1K-XModem "G" for link-level error-corrected lines) will be implemented in
later versions, as will support for other SVGA adapters/modes.


REVISION HISTORY:

0.9c - original "raw" release

0.9f - added John Bridges' exellent bankswitching code to implement card types
besides Tseng. Updated mode selection code to work with other card's
640x480x256 modes. Corrected bug causing connection to be broken at
end of transfer. Corrected bug causing image capture file to not be
saved properly.

0.9h - first BETA release. Fixed a new capture bug. Added alarm sounds when
the image capture is aborted in the middle of an image due to disk
error (the image will continue to display.) Cleaned up a few rough
spots. Added default extension (.GIF) forcing.



KUDOS:

Chris Young for his major help with the LZW decompress routines and EGA video
code.

John Bridges for the SVGA bankswitching code and modes-selection code for
Paradise/Video7/Trident/C&T chipsets.

Tim Wegner, Bert Tyler et al for some video code from their FRACTINT program.



Steve Sneed
409 San Juanico
Santa Maria, CA. 93455

CIS ID 71520,77 or 70007,3574
or
The GRAFX Group/Minds in Motion BBS 1-714-240-7459