On a sunny day (Thu, 18 Mar 2010 12:57:15 +0000) it happened Nobody wrote in :
The situation in other circles may have been different. The other
Sinclair Z80, ZX81, and Spectrum were Z80 basesd and had not that bug :- Z80 has no bugs as far as I know, and I coded a lot for it. It has many 'hidden' instructions though. Wrote a disassembler for it:
I never used the 6502 myself.
-- Pity... It was basically a 6800 with no hardware multiply. JF
John Fields a écrit :
IIRC the 6800 didn't have any hardware multiply. It was the 6809.
-- Thanks, Fred.
Sigh. Commodore published technical manuals for the VIC-20, C-64 and most other computers they sold. They had schematics and data sheets on the 6500 series ICs. Other companies published a lot of books after reverse engineering the commodore line. i still have most of mine, including the ones about the 1541 and other drives.
-- Lead free solder is Belgium's version of 'Hold my beer and watch this!'
Yep, and simple-minded assemblers/disassemblers like Supermon by Jim Butterfield were available pretty much immediately upon their release -- since I believe he already had them for the PETs and just needed a few quick code changes to work on the VIC and C-64.
I think I first heard of this particular problem in some article on software copy protection that suggested that making use of this undocumented behavior of the 6502 might lead would-be pirates astray. In retrospect I doubt that would stop anyone for very long -- if you knew anything about hardware design it might occur to you that something "funny" might be happening when you crossed a page boundary. (Granted, no Google back then to verify/communicate such ideas almost instantaneously...)
"Mapping the C-64" and "Inside Commodore DOS" were awesome... those and the Commodore hardware reference manual were a very good starting library.
---Joel
Stop it, you guys are reminding me of my age!!!!!!!!!!!!!!!
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