[Techtoolslist] Finally - a use for the TMS9900 pod!

[John Robertson]

On 2024/07/01 1:53 a.m., Mike Coates wrote:
> As far as I can remember Looping uses one.
>
> there may have been 1 more, but cannot think of it at the moment.
>
>
> From pinout the CRTC looks like a 6845 (rather than the TI one ...) -
> usually has the markings removed, along with the 9981
I have a Universal service bulletin (#002) that identifies the two chips 
- the CPU as a TMS9981 and the CRTC controller is the Hitachi HD46505
>
> Don't forget the 9981 fetches words as two 8 bit reads, where the 9900
> reads all 16 bits at once.
Oh, that could need some logic glue then...
>
> p.s. did you sort the S2650 adapter, did grounding that pin work ?
Went on to other projects, will get back to the S2650 adapter sooner or 
later. As I recall grounding helped...
>
> Mike

Thanks,

John :-#)#

>
> On 01/07/2024 03:03, John Robertson via Techtoolslist wrote:
>> It turns out that Universal used the TMS9981 CPU in Cosmic Guerilla -
>> someone sent the board to me to service. I haven't checked if there are
>> any other Universal games that ran that CPU.
>>
>> Interesting that TI reversed the order of the addresses and Data lines
>> from what is now the convention. Their D0 is most folks D7! Our A0 is
>> TI's A13 on the 9980/81...
>>
>> Need to see if I can make a simple adapter 9900 <--> 9981, unless
>> someone made one and is willing to sell me a copy...
>>
>> Thanks!
>>
>> John :-#)#
>>
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