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From: John Robertson <jrr@flippers.com>
Newsgroups: sci.electronics.repair
Subject: Re: TMS9981A needed - 8-Bit TI CPU...
Date: Wed, 22 Jan 2025 23:29:27 -0800
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On 2025-01-22 8:04 p.m., root wrote:
> John Robertson <jrr@flippers.com> wrote:
>> Hi Folks!
>>
>> Anyone have one or more of the old TI CPUs? The usual suspects don't
>> stock it (Unicorn, Abra, Jameco...). I have a customers game board in
>> where the CPU was backwards and previously destroyed...
>>
>> In case anyone is curious the game was from Japan - Universal's COSMIC
>> GUERILLA.
>>
>> This is NOT the TMS9918A - video chip - that some folks are trying to
>> emulate with Raspberry Pi(e)s.
>>
>> Thanks!
>>
>> John :-#)#
> 
> 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 :-#)#
-- 
(Please post followups or tech inquiries to the USENET newsgroup)
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