need info about graphics mode on AT&T 6300

[Paul S. R. Chisholm]

< If you lined all the news readers up end-to-end, they'd be easier to shoot. >

In article <220 at tiger.Princeton.EDU>, wei at tiger.Princeton.EDU (P Wei) writes:
> I need the info about the [640x400] graphics mode on the AT&T 6300 computer:
> (1) The codes I need to send to the video IO port to initialize the screen
>     into graphics mode .
Just as you would for a CGA, use interrupt 10H, with AH set to 0; but
instead of setting AL to 6 for 640x200, set it to 40H for 640x400 mode.
48H yields 640x400 graphics with "tiny text (80x50 text)".  Int 10H
clears the screen as well as setting the mode.

> (2) The Base address of the video ram.
B8000.

> (3) How to access each pixel given the address (x, y).
The CGA 320x200 mode stores lines 0, 2, 4, etc., through 198 at B8000,
and lines 1, 3, 5, etc., through 199 at BA000.  The AT&T mode stores
lines 0, 4, 8, etc., through 396 at B8000, lines 1, 5, 9, etc., through
397 at BA000, lines 2, 6, 10, etc., through 398 at BC000, and lines 3,
7, 11, etc., through 399 at BE000.  The 6300 in 320x200 mode has a
second page beginning at BC000.

> (4) The codes to get back to text mode.
Int 10H again.

> I know how to do this for Hercules card on a PC.
I gave you instructions related to CGA graphics, because that's what
the AT&T super high resolution graphics mode is most similar to.  For
more information on CGA modes, consult Peter Norton's book on
programming the IBM PC, or any similar book.

> Thanks in advance.
You're welcome.  The preceding information came from the AT&T Personal
Computer 6300 System Programmer's Guide, com code 999-802-200IS.  If
that's not available (the PC 6300 has been discontinued), ask for a
similar manual for a more current system (e.g., PC 6310, 6312 WGS, 6386
WGS, 6300 WGS).

> wei%tiger at princeton



-Paul S. R. Chisholm, {ihnp4,cbosgd,allegra,rutgers}!mtune!lznv!psc
AT&T Mail !psrchisholm, Internet psc at lznv.att.com
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