Altair parts substitutions

From: allisonp <allisonp_at_world.std.com>
Date: Tue May 23 20:13:45 2000

>> > I wondered at the time what the difference was between an 8205 and a
>> > 74LS138. Now I know...
>> >
>> > -tony
>>
>> Hi Tony
>> As I recall, the difference was that the Intel parts could
>> stand a much lower negative voltage ( -10V? ) than the general purpose
>
>Well, from what Allison was saying, there's a TI silicon die in that
>8205.


Why would it see -10V??? Your thinking maybe of the 8224 clock gen?

>_Apart_ from the clock lines (and power supplies :-)), I thought all pins
>on the 8080 were at standard TTL levels. Certainly the address bus was,
>which is where you'd be most likely to use a 3-8 decoder.


Yes they are but not much drive, 2 LS loads are it.


>> I recall, the 8205 were also Schottky's.
>
>Possibly. But wether it's a 74138, 74S138 or 74LS138 makes little
>difference on the average 8080 system memory board...


Right on. It was LS part. Also it was introduced when the 8085
was released and not the 8080.

Whats funny is when TI had that 74LS yeild bust in the late 70s
that part became real important to intel.

Allison
Received on Tue May 23 2000 - 20:13:45 BST