VAX 11/730 quickie

Mike Ross tmfdmike at
Fri Feb 19 18:07:18 CST 2016

On Sat, Feb 20, 2016 at 12:22 PM, Mike Ross <tmfdmike at> wrote:
> Just started working on mine - been a back-burnered project for a long
> time. Unfortunately all the cables were cut when it was dismantled; I
> was lucky to grab just the CPU.
> Got it powered up ok - no drama there. I faked cables to the port on
> the WCS which drives the console and hooked up my trust VT220 at 2400
> baud. Nada. No self-test prompt; no ROM> prompt.
> Maybe I've messed up the faked console cable; I'll check - already
> tried obvious things like making sure Rx & Tx were crossed (it's a
> three wire cable according to the schematics - Rx Tx Gnd; no flow
> control). But I'd like to know more about the assorted LEDs on the CPU
> boards; maybe there's a clue there if it's not getting far enough into
> the self-test to display console output. There's a fair few LEDs on
> the M8391. But the doc I've looked through on Bitsavers doesn't seem
> to document their meanings and interpretations. Can anyone help on
> that point?
> Hopefully this link works:

OK apparently link didn't work... here's the pic:

See row of red LEDs on M8391? On power-up the leftmost LED lights and
goes out. Then the rightmost two LEDs light and stay on...

'No greater love hath a man than he lay down his life for his brother.
Not for millions, not for glory, not for fame.
For one person, in the dark, where no one will ever know or see.'

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