24 Feb
2022
24 Feb
'22
11:51 a.m.
On 2022-Feb-24, at 11:32 AM, Paul Berger via cctalk wrote:
On 2022-02-24 14:16, Brent Hilpert via cctalk wrote:
> On 2022-Feb-24, at 8:29 AM, Clemar Folly via cctalk wrote:
>> I'm looking for information about Texas Instruments TB-759933 IC.
>>
>> Does anyone have the datasheet or any other information about this IC?
>
> A search shows this question was posted over here, with a picture:
> https://atariage.com/forums/topic/331769-unknown-cart-ic-please-i-need-some…
>
> It looks like a home-made board for a plug-in ROM expansion for we-are-not-told.
> The "TB 759933" is 14-pin DIP, dated coded 7226, has a house number of
"239 2100", but it's on a board with a 27256 from 1985.
> It looks like somebody hacked up this board with on-hand parts.
>
> 60 seconds of reverse-enginerring from the limited view in the picture suggests
it's likely involved in the address decoding to select the on-board EPROM. The 759933
interconnects with a 74LS10. The LS10 appears to have connections to the chip-select and
output-enable of the 27256 EPROM.
>
> TB 759933 is not a standard TI number but TI sometimes identified parts they were
second-sourcing by embedding the original number in an expanded number.
>
> So a guess is this is a 933 DTL dual 4-input (AND function) expander, being used
not-strictly-correctly to drive a TTL input.
>
> The 933 should be basically 2*4 diodes.
>
> A complete reverse-engineering of this trivial board would likely explain the overall
intended function.
2392100 Look like an IBM house number for a 7400 quad
NAND
Paul.
Glad you said that, I wondered whether that might be IBM, but I'm not very familiar
with their numbers and don't have a xref.
7400 makes some sense with the board: pins 1&2 and 4&5 are blobbed together, i.e.
acting as inverters; and the interconnections with the LS10 as far as can be seen appear
to then make sense as outputs-inputs.