PDP-11/23 Debugging

Ben Sinclair bensinc at gmail.com
Sun Nov 16 20:54:06 CST 2014

I happened to already have a manual wire wrap tool, and it actually works
pretty well! I was able to wire wrap the jumpers on my serial card and they
seem pretty secure.

However, I'm having other strange problems now. I'm not sure what I did,
but at the moment I can't seem to boot into XXDP as I could before. It
halts back to ODT at 00104, but I know from past runs that the restart
address is 152010. If I do a 152010g, it does run XXDP and seems to work.

I was messing with the halt option on my DLV11, but I currently have it set
to go to ODT on break, which is what it's always been set to. I'm actually
not sure what the common setting for that would be. It's either break,
boot, or do nothing. It was on break earlier, and worked, so I think
something else may be wrong.

I'm currently only running with the CPU, memory, and serial boards

I did try what you suggested while trying to fix the initial problem. I
reseated the boards and made sure the jumpers were secure, and reseated the
two chips on the CPU board.

I did receive my "new" M8186 from eBay, but it's missing all of the
jumpers, and there is a strange modification... On my original M8186, there
is a capacitor on the left, after the first row of chips, when looking at
it from the tab side. The "new" one has that capacitor replaced with a
piece of perfboard with two smaller capacitors, and a two pin connector. I
have no idea what that might be, but I don't think I should try this board
until I figure it out.

One thing I was thinking of trying was moving the socketed chips from the
new board to the old... I don't have any other great ideas right now though!

On Tue, Nov 11, 2014 at 6:11 AM, Noel Chiappa <jnc at mercury.lcs.mit.edu>

>     > From: Ben Sinclair
>     > what is the best way to connect the wire-wrap jumpers? I've never
>     > actually wire wrapped anything, but is that what I should do?
> Well, I use wire-wrap, but anything that makes a good connection and
> doesn't
> get in the way (of other cards, etc) is fine, really. Don't feel you have
> to
> use wire-wrap, or anything.
> If you want to wire-wrap, there are two ways to go. They used to make
> manual
> tools for wrapping the wire, but I've never used those; I learned with a
> gun.
> Those are available on eBay now for relatively cheap, since wire-wrap is
> now
> more or less obsolete (if you're slightly patient - I paid $25 for a kit
> containing two guns, a bunch of different tips for different gauge wire,
> several packages of pre-stripped wires, several of the strippers that cut
> the
> wire and strip the right amount, and some un-wrap tools - a great deal :-);
> that's the way I'd go.
> They are pretty easy to use; the only real trick is to learn how to apply
> just
> the right amount of up-down force while doing the wrap. Too much up, and
> you
> tend to pull the gun up as it wraps, and you don't get a nice tight wrap.
> Too
> much down, and you get an ugly ball at the bottom of the post as the wrap
> winds around itself. The trick is to try and hold the gun neutrally
> weighted,
> and as it wraps let it push _itself_ up the pin, producing a nice tight
> wrap.
> And of course you can do test wraps, and undo them if they come out looking
> bad. It doesn't take long to get reasonably good with it.
>         Noel

Ben Sinclair
ben at bensinclair.com

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