20 May
2009
20 May
'09
10:59 p.m.
Tony Duell wrote:
I fixed an incorrect jumper (my boardset was configured for the EIS
option, which I do not have) and that solved the incrementing problems.
Now that that's fixed, programs I've toggled in seem to be running
correctly, too. Yay!
I'm fairly sure I have the grant continuity cards in the right way
(they're not exactly clearly labeled -- these are the tiny ones that
lack handles). They're in the D connector of the empty slots, and
oriented such that the label "Grant Continuity" is the right way up (or
put another way, such that the conductors on the card edge are facing
toward the back of the machine).
I'll check the NPG jumpers -- here's a stupid question -- how do I find
where they're supposed to be? I've looked all over for a simple diagram
showing which pins are CA1 and CB1, but I'm not finding them...
Thanks,
Josh
Hey all --
I'm one step closer to bringing my 11/40 back to life -- the front panel
is now responding and I can examine and deposit memory.
But the machine is only responsive without the Unibus terminator (an
M9302) installed. If it's installed, the front panel is basically hung
-- toggling "Start" causes a brief flurry of activity, but that's the
only thing that causes any response.
Without the terminator installed, the front panel more or less works, I
can examine and deposit memory, load the address register, etc... but I
can't get any toggled in code to run, obviously -- it traps to the bus
error vector at 00004.
I don't see why that is 'obviosu' A short Unibus will normally work with
a termination at one end only.
(There's also an odd issue, which I doubt is
related, but
Examining/Depositing does not correctly increment the address --
starting from 0, it's "0, 2, 6, 12, 16, 22, 26..." and if I start at 1
it's "1, 3, 7, 13, 17, 23, 27...")
I think you should look at that too. It is clearly storing the '4's bit
correctly, since it does take account of it in future increments. THis
looks like a bus buffer problem, but you want to find out.
I currently have the CPU boards + MMU option
installed in the correct
order with a SLU card in the SPC slot, and an M981 connecting to a
4-slot Unibus backplane with a single 64K MOS memory card (M7891) in
slot 2 -- all other slots have grant continuity cards installed. The
Unibus terminator is installed in the last slot.
Any ideas?
Normally when a system hanges if you had an M9302 terminator, it's a
grant problem (as I've mentioned before, if a grant actually gets to the
M9302, that card assets SACK, causing the CPU (or more precisely the
arbiter) to deassert the grant line. If the 'grant' is due to a signal
floating because of an open grant chain, the CPU can't deassrt the grant
line _at the terminator_, and the system hangs with SACK asserted).
Anyway, you mention you've got grant continuity cards in all the empty
slots. I assume the're in the right connector (D), and the right way
round :-). In which case, check the NPG jumpers on your backplane
(wirewrapped links from pin CA1 to CB1).
What I normally do is use a logic probe to see just
which grant is
getting to the terminator. Then make sure it's not being asserted by the
CPU (there could be a fault in the CPU, a dead buffer or something), and
then check it along tbe backplane to find out whrre it's starting from.
-tony