[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Steal RAM -- Question



mmphosis wrote:
> Performing a "write" operation on the odd addresses between $C080.$C08F
> should have the affect of throwing the switch twice, thus enabling the
> soft switch.

No, it won't. The accesses must be reads.

> But, it sounds like this won't work with the 65C02.

It doesn't matter which chip you choose. STA won't work. There is the
interesting case of read-modify-write instructions, however. Take the
following two code snippets:

(1)
 LDX #$00
 ROL $C081,X ; write enable bank 2 on 6502 or 65C02

(2)
 LDX #$82
 ROL $BFFF,X ; write enable bank 2 on 62C02 only

Cheers,
Nick.