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8-bit acorn hardware • Re: Fault finding index

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Bog standard Master 128 - odd CMOS behaviour.

Power on with 'R', prompts for <break>, then returns startup banner however typing anything yields crazy repeat/delay sssssssssssseeeeeeeeeeeettttttttttttttiiiiiiiiiiiiinnnnnnnnnnnnnngggggggggggggsssssssssssss.

Deft fingerwork enabled me to enter *ST. and it showed both repeat & delay set to 1. Repeated 'R' power-ons yielded same results.

I created a disk on another Beeb, the !boot of which contained *co. delay/repeat 50 which then allowed me to use the machine.

*ST. showed delay and repeat both at 51. Set it to 40 and *ST. showed 41.

I had a 80186 board installed and that was always enabled. No combination of *extube or *notube would disable it.

So, completely strange behaviour.

Posted on *. and after a bit of back-and-forth I ordered a replacement CMOS chip, socketed the mobo and fitted the chip.

Sane operation resumed.

Statistics: Posted by ihardcas — Fri Jun 06, 2025 1:00 am



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