Altair parts substitutions

From: allisonp <allisonp_at_world.std.com>
Date: Mon May 22 17:22:21 2000

>> Anyway, some parts have become scarce, so I would have to use
substitutes.
>> For example, Jameco no longer carries the 8T97 buffer/driver. As I recall
>> the 8T97 is an LS373 without the inverter on the gate *and* is faster and
>
>I thought that the 74LS367 and 74LS368 (the latter being the inverting
>one) were almost direct substitutes. I think the 8Txx parts can drive a
>heavier load, but I doubt if this will cause problems in an Altair/Imsai


Tony is right. 8t97 and 8t98 are close to the 74LS367 and 74ls368
in drive and exactly the same pinout.

>The '373 is an octal transparent latch (with 3-state outputs) and is not
>the same thing at all.


the '373 wasn't available when the altair was new.

>> has a higher drive current. I've heard that the MC6887 is a sub, but I
can't
>> find a datasheet on it.
>>
>> The 8101 dual-port 256bx4 RAM is no longer available, but Jameco has a
5101
>> which looks like a likely sub. I would forego this type for a larger
SRAM,


That would work, the difference is the 5101 is cmos and the 8101 is mos.

>I can't find the 8101 on any of the S100 card schematics I've looked at,
>so I wonder what on earth it was used for.


try 2101. the first ram card was a 256byte one using 256x4 parts if
memeory serves.
The denser cards were 2107/TMS4060 4kx1 Dram based.

He may have meant seperate Input and output like the 2102 (1kx1).

Allison
Received on Mon May 22 2000 - 17:22:21 BST