classic-games.com

Atari 7800 Development

Subject:	Re: 7800 Expansion port???
From:	David Tipton <6500dtpt@ucsbuxa.ucsb.edu>
Date:	Fri, 21 Jun 1996 10:03:17 -0700

On Fri, 21 Jun 1996, Lee Seitz wrote:

> In article <4qccat$as6@ucsbuxa.ucsb.edu> you write:
> >mostly a/v signals.  I suppose the keyboard was to attach through the 
> >cartridge port.  The BASIC for the 7800 was in development and was a 
> >modification of the Atari BASIC originally written for the 400/800.  I 
> >have a message from one of the authors archived around here somewhere.  
> >If anyone is interested in seeing it just let me know and I will post it.
> 
> Please do.

OK.  This was originally posted in comp.sys.atari.8bit, and Mr. Cortese 
had Bill Wilkinson's permission to re-post this message about his work on 
the 7800.

>From comp.sys.atari.8bit Fri Jan  1 12:47:47 1993
Path: 
ucsbcsl!mustang.mst6.lanl.gov!data.nas.nasa.gov!ames!haven.umd.edu!uunet!p
ortal!cup.portal.com!Rick_Michael_Cortese
From: Rick_Michael_Cortese@cup.portal.com
Newsgroups: comp.sys.atari.8bit
Subject: Trivia
Message-ID: <72652@cup.portal.com>
Date: 31 Dec 92 00:13:50 GMT
Organization: The Portal System (TM)
Lines: 59

Well, reprinted with Bill's permission:


Message : 12102 [Open] 12-07-92  7:25pm
From    : Bill Wilkinson
To      : Bill Esquivel (x)
Subject : The 7800
Sig(s)  : 1 (General Information Files)
There is 1 reply

The 7800 was developed by General Computer Company back in Cambridge, MA
(next door--literally--to M.I.T., with lots of work being done by MIT
students/grads/etc.).  GCC also did many, many Atari coin-op  games
back then (example: Ms. Pac Man, some of the driving games, others I don't
remember--oh, yeah: Robotron).

As originally conceived, the 7800 would allow you to plug in a keyboard (I
think into the cartridge slot, with the cartridge then extended out?  But
my memory is not clear on this) which would have an 8-bit standard SIO
port, so you could hang any device you wanted off of it (printer, modem,
etc., etc.).

The OS had hooks in it for all of this.  The CIO/SIO was more simplistic
than the standard 8-bit stuff: for example, if you wanted to grab any of
the interrupts (display list equivalent, etc.) you basically had to take
over the entire OS: no hooks a la CIO.

We modified Atari BASIC and Atari DOS to run on this CIO (which was
written from scratch by a guy back at GCC).  The DOS was much simplified:
no command processor at all, only one file open at a time, only one disk
drive available (with fully loaded RAM, you could override some of this
by loading disk-based extensions...but we never got that far).  The BASIC
took over all the operations of the DOS command processor (shades of the
C64, Radio Shack TRS80, etc.), so it had commands to ERASE, RENAME,
PROTECT, UNPROTECT files, etc., etc.  DIR of course.  Seems to me I
...scratch that...I remember for sure:  It even had FORMAT and FORMAT
UNCONDITIONAL (FORMAT alone would give an error if the disk already had
anything recognizable on it).  No COPY, but I remember writing a COPY in
the 7800 BASIC just as a demo, since the BASIC had BGET and BPUT built in.

Basically (no pun intended...though enjoyed) it was a neat little REAL
beginner's computer.  I think it was 24 by 32 character display, but not
sure on that.  I know the 7800's display list was only capable of 32 (or
was it 31?) characters per display list entry.  But the unique thing about
the 7800 was that it had a "DISPLAY LIST LIST" which was a list of
"DISPLAY LIST"s where each "DISPLAY LIST" described only 8 or 16 scan
lines of the screen but allowed any number of entries for that segment, so
you COULD do 40 characters across by, for example, using two 20-character
display list entries: one on left, one on right.  Bizarre video processor;
probably most powerful ever put on an 8-bit machine until the Nintendo
arrived and wiped them all out.

As for prototype games, etc., they would likely be found back at GCC.

Incidentally, if you didn't know, after Atari folded the operation GCC
moved into the Macintosh market and produced (still produces?) laser
printers that understand QuickDraw and so do not have to have postscript
drivers...cheaper and faster, presumably.  Anyway, they lasted a lot
longer than the 7800 did.
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