Hello,
Ruud <ruud.baltissen@abp.nl> wrote:
> Remark: it just occured to me that the 6520 maybe only is
> register-compatible and not timing compatible to the 6821. Being a 65xx-IC
> it could be timing-compatible with the 6522 and we all know about the
> problems connecting this 6522 to the C64.
<guess from memory>
I'm sure I've written this before, but as far as I remember, one could
say that the 6502, 6522 and so on belong to the 65xx family (which is
familiar with the 68xx), but the 6510, 6526 and 6567-6569 do not belong
there, literally, because of timing differences.
The 6502, 6809 and so on don't only use one half of PHI2, because
their hold- and setup-times partially fall on the other half, isn't it?
This is not true for the 6510, 6526 and 6567-6569 since they were de-
signed to be able to share the bus.
I also seem to remember that connecting a 6821 to the 6510 might (i.e.,
it depends upon the particular "instance" of the device used) require
the same work as connecting a 6522, for example. Anyway, I, personally,
have never done this, so cannot speak from experience.
Any comments?
Gruß,
Spiro.
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