I came across a reference to a “Cortex” computer that was based on the TMS9900 from TI (same as in the TI 99/4A.) I had to go digging, and so far information is scant. But I found this:
http://www.quantums.info/oldcomputers.htm
And here is the kit manual.
http://www.quantums.info/cortex/Powertran_Cortex_II_Manual.pdf
I’m not sure about Cortex II vs. just plain Cortex. It seems the original was written up in ETI magazine in 1982. The Cortex II seems to be a kit offered by Powertran Cybernetics. More digging required!
EDIT: This appears to be a scan of the original article.
3 Likes
That’s a pretty interesting memory architecture, using DRAM and having DRAM shadowing of the ROM (so that writes to ROM addresses transparently fall through to DRAM). The 8-bit memory bus is a bit unfortunate, although I’m sure the cost-effectiveness at the time made it worthwhile. The TMS9995’s on-board register file may make up for that (compared to the TMS9900’s off-board registers) in practice.
The TMS9929 (9928 for those of us using 60 Hz displays) is a pretty amazing video chip, as well! As Quinn Dunki recently summed up the 8-bit era machines (paraphrasing), their bizarre architectures make sense if you think of them primarily as a video generation system, with a CPU bolted on the side. The powerful one-chip video capabilities of the TMS9918/19/28/29 allowed the computer to do more computing and less graphics production.
1 Like