Re: Difference between R65C02 and original 6502 (wrt 6509 emulation)

From: Michał Pleban <*lists_at_michau.name*> Date: Sat, 20 Apr 2019 11:24:26 +0200 Message-ID: <5CBAE54A.7040502_at_michau.name> · lists_at_michau.name

> I had to go check the code to be sure, but currently, all writes go to
> the bus, regardless of state.  However, it does raise the question of
> whether the real 6509 places the address or data or a proper r/w signal
> on the bus during a read or write to $0 or $1.
> 
> Michal?

Yes, it does place the address and R/W signal on the bus when writing to
$0/$1 but not data, so the underlying RAM is overwritten with what was
previously floating on the data bus.

Regards,
Michau.