3 Nov
2013
3 Nov
'13
1:25 p.m.
I misplaced this card and cannot figure out which machine it goes
with. There are no markings on the board beyond what is on the chips.
Any ideas what this might be? That's a DB25 in the lower left of the
full board pic.
There are 2 pictures int this imgur set.
http://imgur.com/3QcLnlZ
Thanks,
Win
3 Nov
3 Nov
2:19 p.m.
Win,
This is a serial port or multi serial port for a 9995 system. The I/O
bus is serially clocked with the 9902 being the serial uart. The 9901 is
a parallel I/O part of a system.
the 1488 in the output side of a +-10 or so output channel.
ti had other drivers and receivers that were less prone to blowing up
than the 1488 but they also made the 1488.
I only could find one photo on imgur only thing that showed up was the
one photo with these three chips. There was no "next" or anything but
the 'photos of the day" to the right side of the page I got.
We had a 16way for the microdata 1600 that used these. We got full
modem control x 16 channels on a 11 x 8.5" Microdata board, which was
really high density.
jim
On 11/3/2013 1:25 PM, Win Heagy wrote:
I misplaced this card and cannot figure out which
machine it goes
with. There are no markings on the board beyond what is on the chips.
Any ideas what this might be? That's a DB25 in the lower left of the
full board pic.
There are 2 pictures int this imgur set.
http://imgur.com/3QcLnlZ
Thanks,
Win
2:25 p.m.
On Sun, Nov 03, 2013 at 04:25:24PM -0500, Win Heagy wrote:
I misplaced this card and cannot figure out which
machine it goes with. There
are no markings on the board beyond what is on the chips. Any ideas what this
might be? That's a DB25 in the lower left of the full board pic.
It's probably a serial card for a TI-99.
The 1488 is a TTL to RS232 level converter. I replaced a few in my Amiga back
in the day. This would imply that the DB25 is a serial port. It's usually
paired eith a 1489 to convert in the opposite direction, but I don't see on on
your board. It's possible to cut corners and replace the 1489 with cheaper
discrete components, which is perhaps what's happened here.
I've not encountered the TMS9901 before, but a quick search finds
http://www.mainbyte.com/ti99/hardware/chips/9901.html which is a fan site for
the TI-99, and also tells me the TMS9901 is "the interface chip for the TMS9900
CPU. It is the direct communication chip for the keyboard, direct sound output,
joysticks, and cassette system." There's a TMS9902 on the board, presumably
another support chip for the TMS9900.
As far as I can tell, pretty much only the TI-99 used the TMS9900.
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