[BBC-Micro] Acorn Electron Repair - Replace 6502 (unlikely)

Dave Curran bbc at pdcurran.co.uk
Thu Mar 1 07:39:21 GMT 2012


On 26 February 2012 23:59, Phill Harvey-Smith <afra at aurigae.demon.co.uk>wrote:

> On 26/02/2012 02:59, Rick Murray wrote:
> > You'll need to ensure a replacement is pin compatible. I think a
> > 65C02 will work okay (but note that games or such using illegal
> > instructions would fail), not sure sure about the more recent WDC
> > chips, best check a datasheet if not picking up an original.
>
> WD65C02 has a mostly compatible pinout
>
> pin     6502    65c02
> 1       VSS     Vector Base Pull (output)
> 5       n/c     Memory Lock (output)
> 36      n/c     Bus Enable  (input)
>
> Of note is that pin 1 is an output on the WD chip so must not be
> connected to VSS. Also Bus Enable is active high so will need pulling up
> to +5V, as this pin should not be connected to anything on the Electron
> motherboard, it should be OK to connect a 10K resistor between this pin
> and VCC to get the required +5V.
>
> Cheers.
>
> Phill.
>
>
Thanks for the info, I hadn't realised it wouldn't be a drop in
replacement. I've managed to get a traditional 6502 instead and the
Electron's up and running again.

Thanks,

Dave
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