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8-bit acorn hardware • Re: Master 128 no beep no display just cassette motor relay click

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IRQ is being held low approx 0.5v

Can't detect any shorts to ground.

Will in turn try lifting the pins and or checks of the select / bus signals on the following...

IC6 (21)

IC14 (4)

IC3 (28)

IC20 (29) - unlikely as key presses detected correctly e.g R to enter CMOS reset prior to booting.

IC11 (19) - unlikely as replaced and keyboard works until I press Break after ctl Break R to reset CMOS

IC45 (7) (unlikely as I get relay click on and off prior to booting implying proper programming of the acia)

Does anyone know what order the various peripheral IC registers are programmed in during boot on a Master?


Thanks

Statistics: Posted by JonnoW — Mon Jul 22, 2024 10:02 am



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