4 Mar
2005
4 Mar
'05
6:04 p.m.
Tony wrote...
Odd... That implies your console card is not
responding. Maybe it's
defective too.
Kinda what I figured :)
But IIRC there's at
least one bit (my memory is weak on this, but I think it's the interrupt
enable bit, maybe bit 6) that you should be able to read and write from
the panel.
Ah ok, good thing I printed off those engineering notes. I'll track
down the
interrupt enable bit and try that.
My idea was going to be to hang a terminal off the
card (assuming you
have an RS232 lead and can decode the word foramt and baud rate settings
[1] and then try writing to the transmit data registers at 777566 or
777656. See if you can transmit chracters to the terminal.
I have the appropriate
cable from the card to mate & lock, I'll cobble
something together to go from that to a terminal. I thought you were saying
just to read/write to that register. I'll decode the rest of the settings on
the board (other than the register address) including the crystal, and hook
up a terminal.
[1] The baurd rate is set by a rotary switch on the
card and by the
frequency of the crystal fitted. I found the quickest way to work it out
was to connect a frequncy counter to pin 17 (Rx clock) and 40 (Tx clock)
of the UART chip. Then divide that frequency by 16 to get the baud rate.
But I guess you don't have a frequency counter sitting on top of your
machine...
Well, as of now, my HP 5315A counter is sitting on top of it :) I'll
make
the measurements tomorrow. I'm glad you said that, because I noticed the
rotary switches for TX & RX speed settings weren't labled (1-10) on the
card. This way I can be sure. However, my usual question follows... if I
connect to 17 and 40 (separately of course), what is the ground reference
location for those measurements? I never seem to know where to hook the
other lead :\ In this case, if I can find a pinout for the UART, I'm sure
that would be a good spot for ground.
I am going to get you to repair that machine properly
-- without swapping
boards -- even if I have to get on the next p'lane across the Pond and
show you where to stick your 'scope probe ;-)
I'm willing to learn, travel
won't be necessary, just an informed instructor
:)
You have got them in the right way round, with the
resistors towards the
front of the machine, I hope! If not, you will have all sorts of
problems.
Yes, component side of all boards is towards the front, including the two
terminators.
Ge ta Unibus pinout, grabe the logic probe, and see if
the data lines
ever go low on a CPU (frontpanel) write operation.
If I can get some 11/45 time
this weekend, I will do just that.
Thanks!
Jay