PDP-8 tautology is clear, one only needs a set of DEC small computer
handbooks to sort it out. My 1973 copy describes all three versions
and their major differences very clearly.
<Well, that's not how I read it. By my reading, Doug's writeup makes
<it perfectly clear that 8/E's and 8/F's were produced simultaneously
<and from a common pool of (largely, but not completely) compatible parts.
Yes, and what isn't made clear is that pool of parts was an evolving one
ove the years.
<>The evolution vectors were as follows:
<> Module updates - example M833 - M8330, M831 - > M8310
<
<In the FAQ, Doug says on this subject:
<
<* Most of the early boards with 3 digit numbers were defective
<* in one way or another, and the corrected boards added a trailing
<* zero. Thus, the M833 was generally replaced with an M8330, and
<* the M865 was replaced with the M8650.
It was the easiest way to ducument the corrections at the modele level.
the 54-class number changed as well. In later years depending on the
change the module(s) (generic statment) would get letters tacked to
the end (and the numbering would go from 2/5 to 2/5/2 and later to 2/5/2/3).
<> Chassis updates - Long box, single OMNI BUS
<> Long box dual OMNI BUS
<
<And in the FAQ Doug agrees with you:
Long box single is an "as ordered" configuration variation if you ordered
a plain 8E you would see one backplane. If you ordered a 32kw disk and
tape system you can bet it would have two backplanes. A la carte
connfiguration ordering was a PDP-8 characteristic and may have been a
new concept to the industry. It was a very configurable machine.
<There's no doubt that there were many ways to mix and match the
<various components produced. I'm a bit uncertain why some folks
<try to apply zoology so incessantly to their computers, when in real
<life folks move parts between systems with wild abandon, but then
<again zoology has always bored me to tears.
That is also true to a point. But the E was always the long box and
the F/M were shorter box and single bus. The fact that customers over
30 years would shuffle things around muddies the matters. then again
the ability to do that is also an omnibus unique PDP-8 characteristic.
Allison
Received on Fri Apr 09 1999 - 23:32:20 BST