Forgottenmyname - Progress - Part 2

[PhilC]

Its actually ST4.4 diag cart and I can't find any description in the manual about I1 errors.

Will try Diagrom and see if that gives us some more insight

[exxos]

ahhh ok, so likely its writing all zeros but reading 1 back I would assume. So either the address isn't being driven somewhere, or its shorted to 5V somewhere.

[PhilC]

And that's the bit I cant find. As I say, the right 0s are D0 to D15 burnout sure about the left lot unless they are address lines. But if so, A0-A15 seem ok as well

[exxos]

Would assume its dataline 1 (bit 1) which is stuck high.

[PhilC]

Ok, so they are both data register bits. Fixed D1 on the left 4 falcon ram chips, now D1 on the other side playing up, LOL. Time to check my soldering

[PhilC]

1 new ram board required. Haven't got any more SMT ram and can't be arsed to remove the chips again.

I did find a lifted track underneath one of the ram chips but fixing that has now given me a I2 ram disturbance.

So time for a new ram solution. Two steps forward with this one but one step back.

It's having a difficult birth this Alpha board but born it will be, dragged kicking and screaming into the real world (well hopefully anyway)

[PhilC]

And another step sideways, LOL.

I've just tried turning the Alpha on today and I actually get a garbled menu for the diag cart. Pushing the relevant buttons carries out the relevant tests as far as I can see at least but the monitor screen stays a 50hz black, LOL.

what do you all think of this?

dodgyserial.PNG (31.11 KiB) Viewed 3420 times

[PhilC]

I've put Diagrom into the Alpha and I get a bit better serial output but still no video. It does let me check the memory out and surprisingly it passes, have tried 3 times now as I didnt believe it.

I'm now wondering if the lack of output is something wrong with the shifter, so I'd better go look for another one if those.

[PhilC]

And...............

ITS ALIVE!!!!!!!!

20190630_150203.jpg (84.8 KiB) Viewed 3416 times

Sorry the pic is a bit crappy, I've got a loose connection on the video by the looks of things

[exxos]