14 Jun
2002
14 Jun
'02
11:12 a.m.
You're much better utilizing the ASCI Port for such things as opposed to the
cart port. The machine was very rushed in design from July 84 to get it
out the door for April 85. The Tramiels thought they were going to walk
into Atari and own the Amiga chipset and Atari 1850XL computer designs,
however on June 30th when the chipset was supposed to be delivered to Atari,
Amiga delivered a check for $500,000 to Atari to pay them back the money
they gave to Amiga to complete the chipset. So they went into breach of
contract and Atari sued them on Aug 13, 1984. The court decision in 87 was
a closed one, and I'm still trying to get a definitive answer on what the
true outcome was. So without the Amiga chipset and having the basic
1850XL design with no chips to put into it, the Tramiels were forced to work
from scratch using some initial designs for a 32032
system that Shiraz
Shivja had done and they pieced together the STs. Heck, the
first batch
of ST's didn't even have ROM chips yet as the OS was still being finalized,
it wasn't until the Sept/85 batch that the ST's were shipping with internal
TOS. :-)
Curt
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <cctalk(a)classiccmp.org>
Sent: Friday, June 14, 2002 3:01 PM
Subject: Re: PET and Magic Sac+
It goes in the
Atari's cartridge port, a little-used connector on the
side of the machine. Used an unusual type of edge connector, and
hardly any software was supplied on cartridges. Some sound samplers
used it, though. I think the signals available were read-only,
fine for ROMs, but preventing the use of the slot for most types
of peripherals.
Yes, IIRC, you had the data bus, some of the address bus and a couple of
chip select lines on that connector. Ideal for a ROM cartridge but not
for much else.
Worse than that, the Glue chip (IIRC) generated a bus error if you tried
to write to the cartridge memory area. So there was no point in picking
up the R/W line from somewhere else.
What some people did was use the address lines as outputs. They'd map a
latch to 256 contiguous memory locations and then use it to latch the
bottom 8 address lines (even on a read cycle). Then reading the
appropriate address from the cartridge port area would set the outputs of
the latch to the right states. A kludge, sure, but it was just about the
only way to do it.
-tony