14 May
2016
14 May
'16
11:33 p.m.
On Sun, May 15, 2016 01:17, Don North wrote:
Bad idea to put this card in an 11/34. As indicated the +12V VDD rail on
the
memory chips
is wired directly to the UNIBUS +15V line in the 11/34 (which can be set
to +12V
in the 11/44).
So you placed +15V (or more likely up to +15.5V or so) onto the memory
chip VDD
lines.
Some 16K chips had a 15V max spec on this pin, others only 13.2V. So it is
possible you
toasted so memory chips, or not, depending on manufacturer and their
sensitivity
to OV.
I'll label the card as 'possible not working' for a test later in a proper
machine.
On 5/14/2016 2:41 PM, Noel Chiappa wrote:
If the bootstrap card is an M9312 with the standard console PROM, it does
NOT
require any
memory to be present/accessible to get to the ODT prompt that prints out
the
registers and
waits for a command. Only until you execute a device bootstrap command
with
'diagnostics
enabled' (the default) does the memory sizing/test/diagnostic code get
exectuted.
Listing: http://ak6dn.dyndns.org/PDP-11/M9312/23-248F1/23-248F1.lst
So the system working to this level with no memory present is normal.
Agreed, a bus probe would really be helpful in further debug. Given that
the
system does not
even get back to the ODT prompt (which would not yet access memory)
indicates
that logic
on the memory card is hanging the bus. Could be a bad bus driver interface
chip
(8641, etc).
I'll hook up the bus analyzer and see it there is something to see.
From Ed
Groenenberg
- insert both CPU cards, KY11-LB card &
bootstrap card, 5 full
grant
cards, DL11-W and bus terminator card.
...
- cntrl + boot shows register dump at printer.
...
All looks ok
I'm surprised the bootstrap ran OK with no memory at all in the machine.
I
vaguely STR that I had a machine that would not work like that, but
maybe I'm
wrong. (DEC bootstaps tend to do things like set the NXM vector, in low
memory, so they can size memory; and when it gets the NXM (since there
is no
memory) from trying to touch the NXM vector, and tries to push the old
PS and
PC to service _that_, and gets _another_ NXM, that 'double bus fault'
often
causes many -11 processors to do a cheap suit) power down machine, add memory (M7981, 128KW)
What's an M7981? Did you mean an M7891 MS11-L?
- power up machine -> run light is on, does
not get cleared by
cntrl + halt.
This is where a UA11 would really help. I had similar issues with an
-11/04,
and the UA11 was a huge help in figuring out what's going on. One glance
and
you can see if a bus line is wedged, or something. - power down & replace memory with grand card
-> run light is
off.
Well, that's good sign - the memory card didn't fry anything, at
least...
- tried a 2nd memory card (M8722, 128KW)
Ooops. The MS11-M needs +/-12V, which is _not_ standard in most
machines/backplanes). The EUB in the 11/24 and 11/44 (which this card is
intended for) does have it. The really bad part is that those same pins
usually carry +/-15V in most MUD backplanes. So hopefully you didn't fry
it.
It does have standard UNIBUS as well as EUB, but there's a jumper, IIRC. In any event, DO NOT use this card again in the 11/34.
It is not
compatible with
the backplane.
Ed
--
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So what
could be the problem here? The bus works without the
memory
Two possibilities off the top of my head. i) The first memory card is
bad (or
configured incorrectly), or.. ii) The M7891 uses +/-15V as well as +5V?
So
maybe one of the other voltages is not so good? But you said the console
worked, and I think that uses other voltages (at least, in EIA mode -
not
sure about 20mA, I never touch the stuff).
Noel