The PDP-11/20 I had 25-30 years ago was easy to work on IN the rack.
You pulled it out on the slides and you could open the "bottom" of
the chasis to work on the backplane. Or, you pulled it out on the
slides AND FLIPPED IT OVER 180 DEGREES and opened the "top" to access
the modules. Needless to say, it had to be in a really stable rack.
Dave
"Jeffrey S. Sharp" wrote:
>
> Well, I've now acquired a PC05 high-speed paper tape reader/punch for
> the PDP-11/20 I'm currently restoring. I still lack the PC11 board,
> though. Megan's list says the following:
>
> M781 PC11 U PC11 control board for KA11
>
> M7810 PC11 U Paper tape reader/punch controller
>
> Do I *have* to use the M781 version, or can I also use the M7810 if it's
> all that I can find? What is the actual difference between the two
> boards?
>
> Next: why were the backplane modules mounted at the top of the BA11, wire
> wrap up, in the 11/20? It's easy to flip the thing over while it's not in
> a rack, but when it's in a rack...
>
> Some trivia: the two partial 11/20's from which this one is being built
> have serial numbers 786 and 1102.
>
> --
> Jeffrey S. Sharp
> jss_at_subatomix.com
--
David C. Jenner
djenner_at_earthlink.net <--- NOTE CHANGE OF EMAIL ADDRESS!
Received on Wed Aug 22 2001 - 18:00:57 BST