Subject: PDP-11/34 Progress Report

From: Jeffrey Sharp <[email-masked]>
Date: Sun Mar 9 04:59:00 2003

I've made some progress with my PDP-11/34. Since last week's PSU
corn-fusion, I pulled all the cards, air-dusted them, air-dusted and
inspected the backplanes, took an inventory of jumper and DIP switch
settings, put a minimal CPU+mem+console card set in, connected the
backplanes to the PSU, and turned on the machine. It was a little more
complicated than that, but I've got what seems to be a working 11/34 in my
living room.

Learned: As I had mentioned previously, my M9312 had a strange start address
dialed into its DIP switches by one of the previous owners. That has to be a
mistake. When the machine boots, it immediately halts. If I manually start
the processor at the correct address for the console emulator, I get a
steady run light. I do not have a console terminal attached yet.

Learned: A previous owner had a rocker-style DIP switch block on the console
DL11-W set backwards (i.e. one's complement of the correct setting). The
DL11-W was being configured with the wrong interrupt vector.

Learned: If you plug in a G727A bus grant card backwards, the processor will
not halt. :-)

To do: My only existing cable that plugs into a DL11-W is for 20mA current
loop. I have a current loop VT52 that I haven't yet tested. I'll see if I
can do that tomorrow. After all, it would be nice to know if the register
printout is actually occurring.

It's so late it's early; therefore, I should go to bed. Tomorrow I'll run
some test programs!

-- 
Jeffrey Sharp

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From: [email-masked] (Tony Duell)
Date: Sun Mar 9 13:32:00 2003

> Learned: If you plug in a G727A bus grant card backwards, the processor will

Mainly because the grant chain is then open, so the M9302 terminator 
asserts SACK. This means that the 11/34 can't be halted from the panel 
(it gets tied up trying to remove the grant that's causing the SACK...)

> printout is actually occurring.

Almost all DL11-Ws have the RS232 driver/receiver chips on them, and if 
you've got one of the few that haven't. it's not hard to add them (1488 
and 1489 IIRC). 

It's also not hard to make up the RS232 cable. I've done it many times. 
Let me know if you want to do this and need pinouts, etc.

I don't know what test gear you have, but if you have a logic probe, then 
you could monitor the TX output of the UART (I assume you have the 
printset). It should blip low (actually a fairly complex pulse train if 
you have a logic analyser) when it's doing the register printout. That 
would at least tell you if the unit was working at all.

-tony

---

From: Jeffrey Sharp <[email-masked]>
Date: Sun Mar 9 22:59:00 2003

On Sunday, March 9, 2003, Tony Duell wrote:
>> To do: My only existing cable that plugs into a DL11-W is for 20mA
>> current loop. I have a current loop VT52 that I haven't yet tested. I'll
>> see if I can do that tomorrow. After all, it would be nice to know if the
>> register printout is actually occurring.
>

Yes, very easy. But I do have a lonely current loop VT52 that (if it works)
desparately wants *something* to send it some bits and bytes to display. How
can I turn down a request like that? :-)

Maybe I'll build a RS-232 cable for the short term so I can test the machine
with a known good console terminal.

> I don't know what test gear you have

Sadly, all I have is one digital multimeter. It's an eBay cheapo special --
not the bottom of the barrel, but darn close to it. Oh, I also have a
Heathkit digital IC tester model IT-7400 that I swiped from a professor's
trash pile back in my college days (i.e. 4 months ago). It works.

I want to get an oscilloscope soon. I've got other things I need to spend my
salary on at the moment, but that might not be too much of a hindrance. My
current plan is to put a relatively large portion of my collection (which
isn't that large) up for trade and hope for a suitable scope in return. Or
maybe I'll sell some of it on eBay and use those proceeds to buy a scope on
eBay. About the best thing I have is a MINC-11 (when it rains it pours,
eh?), but there are also various PDP-11 parts, two HP-85s, a couple of
TRS-80s (M3 and M4), some IBM 5150 PCs, an AT&T 3B2/EXP, a bunch of Sun3s,
and some other stuff I can't remember. Sometime soon I'll make a more
detailed inventory, take pictures, and formally announce it. I figure all of
that stuff combined should (at least) net me one good scope or logic
analyzer.

-- 
Jeffrey Sharp

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From: Tom Uban <[email-masked]>
Date: Mon Mar 10 07:47:00 2003

Hi Jeffrey,

You may recall that I am interested in your 11/70 BA11-F, et al. If you
still have it and are interested, I have an HP 1630G logic analyzer
that I would be willing to trade you for the BA11-F. I can post some
pics and the operator's manual if you would like...

--tom