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 $AB) but I think this was mostly based on the C64. On http://www.s-direktnet.de/homepages/k_nadj/opcodes.html this opcode is commented as anding the byte with the accumulator and moving the results to x. So... lda someVariable and #nn tax could be replaced with lda someVariable lxa #nn Keep in mind that this is for the Atari 8-bit section of the site. The C64 section says the result is... lda someVariable ora #$EE and #$nn tax 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, Dennis ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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