PDP-11/23 Debugging

Ben Sinclair bensinc at gmail.com
Sun Nov 16 21:04:19 CST 2014

I just tried swapping the chips from my "new" M8186 to the old, and have
the same result, by the way!

On Sun, Nov 16, 2014 at 8:54 PM, Ben Sinclair <bensinc at gmail.com> wrote:

> 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
> installed.
> 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>
> wrote:
>>     > 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

Ben Sinclair
ben at bensinclair.com

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