Some Progress on -8/m Mem problems

From: Zane H. Healy <>
Date: Thu Nov 25 19:10:14 1999

>Yes, it's very similar to the 7401 (and to one other 74xx chip that I
>There's some difference in drive capability and/or output saturation
>voltage, but practically, if your Omnibus/Unibus isn't that long you can
>use a 7401 as a bus driver in DEC machines.

OK, seeing as how the 7401 can more or less be substituted for a 8881 I've
got a question that belongs in the "Wacko File". I've been trying to see
if there are any equivalents to a 384 or 8251. I've not found one yet for
the 384, but the 7442 and the 7445 both look fairly simular to the 8251,
unfortunatly the pinouts are wrong. What is to stop me from building a
setup that will convert a 7442 to a 8251. Or doing the same thing for the
384 when I find a chip that will work?

It would probably involve running wires from where the chip is supposed to
go, to a socket with the actual chip. It looks to me like it would be
work, but I don't know what kind of problems that might cause.

>> Well, there is at least one person locally that might have some spares if
>> I'm lucky. I don't suppose they're used on MicroVAXen or if necessary
>> Q-Bus PDP-11's
>Unlikely. You might find the odd one on Unibus boards, but I'd rather not
>strip one of those.

Oh, I was hoping on some of the LSI-11 stuff I've got that is the same age.
I don't want to go tearing up Unibus boards if I can help it. In either
case I'd make good notes and put them with the donor board so it could be
repaired at a later date.

| Zane H. Healy | UNIX Systems Adminstrator |
| (primary) | Linux Enthusiast |
| (alternate) | Classic Computer Collector |
| Empire of the Petal Throne and Traveller Role Playing, |
| and Zane's Computer Museum. |
| |
Received on Thu Nov 25 1999 - 19:10:14 GMT

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