TMS9981A needed - 8-Bit TI CPU...

I can't help source the chip, but As I remember the 9900 series were 16 bit processors.

The 9900 was a 16-bit, but the 9980 and 9981 were 8-bit, 40-pin variations. From the Osbourne book - Some Real Microprocessors (page 18-45) :

Table 18-4. A Summary of Differences Between the TMS 9900 and TMS 9980 Series Microprocessors

FUNCTION Addressable external memory DIP pins Data Bus Address Bus External interrupt priorities CRU field width Clock logic /TMS 9900 /32,768 x 16-bit words 64 /16 bits /15 bits /15 /4096 bits /Four external inputs //TMS 9980A/TMS 9981 //16,384 x 8-bit words //40 //8 bits //13 bits //4 //2048 bits //One external input or internal (TMS 9981 only)

Table 18-5. A Summary of Differences Between the TMS 9980A and TMS 9981

Microprocessors FUNCTION Power supplies Clock logic Pin incompatibility ties /TMS 9980A /-5V. +5V. +12V /One external input //TMS 9981 //+5V. +12V //One external input or crystal only / & //DO - D7. INTO - INT2. /Phase3

Messy, but I can't make an ASCII table, you'll just have to imagine it with the cells spaced by '/' and then '//'

John :-#)#

John Robertson snipped-for-privacy@flippers.com wrote: Thanks, I stand corrected. I actually wrote software for the 9900 series (16 bit) and interacted with TXN on some of their software back in those days.

Hey, no problem! I suspect these variations were hardly used at all - just the odd video game where someone had a Developers Kit for the CPU and built the game around it. I've talked to a few game developers and that was exactly why they used some odd-ball chips! Handy Developers Kits and support from the kit's factory...

John :-#)#