I've got to disagree on this one. From what I've observed the 100-pin
card-edge connectors are pretty common. I really don't know why, but they
are. Every time I look at the local surplus parts house, I see those old
connectors, in the same box they were in 20 years ago, even though the store
has moved 3 times, with the label "S-100 Connectors, $3.95." They sit right
next to a box of connectors nearly the same size, which says on it,
"Multibus Connectors, $4.95." They seldom have the 30-pair connectors used
on the secondary connector for Multibus-I, nor do they often have the
31-pair or 18-pair connectors used on a PC backplane. Now, I didn't say I
like the price, but there they are.
I don't know of many parts which were used in these old products, with the
notable exception of the UART (TMS 6011, AY5-1013, etc) which were popular
back in the mid-1970's. They were mostly standard TTL, though, which, if
replaced with the currently popular CMOS equivalent may suffer from the poor
designs of yesteryear. Back then we were still learning about race
conditions and setup and hold time violations, and the like. Back then, a
circuit designed to operate from a 25 MHz clock was taxing the limits of the
technology, while today, people don't even blink when the clocks are over 10
times that fast.
Replacing the old "standard" TTL with the still-available LSTTL may prove
hazardous because of timing changes as well, and some of the old tricks with
capacitors as delay elements may not work properly either.
There are plenty of problems. Getting the common TTL of that era won't be
as easy as it was then, but it won't be a lot more difficult. Now that I
know this rebirth is a possibility, I won't throw away any more of the old
standard TTL or small memories, though.
Dick
-----Original Message-----
From: Allison J Parent <allisonp_at_world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Saturday, March 20, 1999 11:50 AM
Subject: Re: Fw: Pre-history of Digital Research
><An important thing to remember is that the Original IMSAI sold for almost
><$1000. So even though a new Pentium II 400 is only $1000 with all the bell
><and whistles there is a cost savings due to selling hundres of thousands o
><the thing. An IMSAI kit maybe a few hundred or so.<
>
>Doing an Imsai would be expsnsive as finding the parts would be costly.
>Many arent made or are such low volume (100pin connector for sure) that
>it isn't going to be cheap.
>
>For example the backplane 18 slots (or was it 22) roughly 13"x18" two sided
>in quantities of 100, I'd bet that would be a $100 right there. Even in
the
>S100 heyday $49 was cheap (no connectors or anything else).
>
>Allison
>
Received on Sat Mar 20 1999 - 13:34:22 GMT