RE: [stella] LXA illegal opcode?

Subject: RE: [stella] LXA illegal opcode?
From: "Oliver Achten" <achten@xxxxxx>
Date: Tue, 27 Jan 2004 11:23:52 +0100 (MET)
Hi Dennis

> BTW, would you consider this a safe opcode? What if someone made a 2600
> with
> a C64 6502? Is the 6502 in the C64 a stock product or is it a hybrid like
> the 6507 or 6502C (used in the A8)?

AFAIK, all NMOS 650x CPUs are based around the same chip mask, so that all
illegal opcodes will definatively work, not matter if it is a C64, C128, Atari
VCS, Commodore Plus 4, 1541 Floppy, etc...


Some opcodes behave unstable due to different system design. On the C64, the
6510 CPU shares the bus with the video chip, which leads to instability with
some illegal opcodes. This *may* not apply for the VCS, since the 6507 is
the only CPU having the address/data buses.

Have a nice day!


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