PC boards and software

From: vrs <vrs_at_msn.com>
Date: Thu Apr 15 19:28:45 2004

> > I was able to design library parts for a number of Gxxx, Mxxx, and Wxxx
DEC
> > modules (needed for the TC08 dectape controller) in just a little over a
day
> > with the Eagle CAD software. These parts need very elaborate symbol
views
> > (essentially logic diagrams, needed to make the schematics that use them
> > readable).
>
> Cool! I'd love to see that.

I can send it to you if you like; the library itself is not too large (but
the TC08 is hundreds of Kbytes).

Basically, there are two packages -- a one high 36 pin socket, and a two
high (2x36 pins) socket. The modules have a symbolic view, usually a gate
or group of gates, and the parts (modules) bind the pads on the socket to
the logical pins, for as many gates (or groups of gates) as the module
implements.

> BTW, do you have an approximate cost for your TC08? Is it posi- or negi-
> bus? I have an -8/i and several -8/Ls (the -8/i is negi-bus) and a few
> TU-56 drives (one on a TD8E, several on a couple of TC-11s). I'd be
> curious to see if your TC-08 replica would work for me.

The board fab wants about $450 for the first one, and about $90 for each
additional. It is a big board, right at the limit of the size the fab will
do (4 layer board, 18" x 14").

Whether it turned out to be Posibus or Negibus would depend on whether you
populated the backplane with M623s or M633s, etc. (As far as I can tell,
there is no wiring difference in the backplane itself.)

I have also been slowly puttering away at replicas of the modules
themselves, but don't have many of those done yet.

The main problem I have is the steep cost of a single board, which prevents
me from ordering one until I am darn sure it is right. I have been unable
to find a TC08 wire list to check my netlist against, so it would come down
to ordering a board, installing connectors, modules, etc. and testing the
result. The chances of it working the first time are none too good, and the
PCB is not easily repaired/patched (half the wiring is buried inside the
board, and half the rest is under the connectors).

Of course, once it was debugged, it would be much easier to build TC08s :-).

If you have a TC08 to debug, the readable schematics and virtual backplane
("show xsta") would help you with your debugging. (I don't have one, hence
the project :-).)

If I was pretty sure the wiring matched DEC's, I'd risk the money to build
one and see how it went. Until then the project is kinda on hold.

    Vince
Received on Thu Apr 15 2004 - 19:28:45 BST