jwest at classiccmp.org
Fri Mar 4 20:04:37 CST 2005
> 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
>  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.
>  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
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
Yes, component side of all boards is towards the front, including the two
> 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.
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