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TonyDuell · 31st Dec 2021, 7:32 pm

I don't know if the other CBM disk drives do this, but the 8050 blinks an error code on the LEDs (all 3 LEDs blinking in unison) if it detects an error at power-up. It does a checksum of the interface processor ROMs, a RAM test, checks communication to the controller processor [1], etc. Each error gives a different number of flashes, so you know the first fault to find...

[1] The 8050 has a pair of 6502s in it. They are clocked in antiphase, which means it's easy for them to have a shared area of memory to communicate through.

31st Dec 2021, 7:32 pm	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,222	Re: Cbm 3040 I don't know if the other CBM disk drives do this, but the 8050 blinks an error code on the LEDs (all 3 LEDs blinking in unison) if it detects an error at power-up. It does a checksum of the interface processor ROMs, a RAM test, checks communication to the controller processor [1], etc. Each error gives a different number of flashes, so you know the first fault to find... [1] The 8050 has a pair of 6502s in it. They are clocked in antiphase, which means it's easy for them to have a shared area of memory to communicate through.