[stella] LXA illegal opcode?

Subject: [stella] LXA illegal opcode?
From: Dennis Debro <ddebro@xxxxxxxxxxxxx>
Date: Mon, 26 Jan 2004 7:27:51 -0500
Hi all,

I've been conversating with Manuel on possible ROM optimizations and he mentioned the illegal op LXA to me. Now from http://www.applefritter.com/apple1/members/pom1/Docs/m6502/6502-6510-8500-8502%20Opcodes.htm it marks this as an unstable opcode (opcode $AB) but I think this was mostly based on the C64.

On http://www.s-direktnet.de/homepages/k_nadj/opcodes.html this opcode is commented as anding the byte with the accumulator and moving the results to x. So...

lda someVariable
and #nn

could be replaced with

lda someVariable
lxa #nn

Keep in mind that this is for the Atari 8-bit section of the site. The C64 section says the result is...

lda someVariable
ora #$EE
and #$nn

which is the result I'm seeing in Z26.

Has anyone used this opcode on the VCS? I plan to try it out this week but I thought I'd ask first.

Take care,

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