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rgmechex
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The Arcade Game that Crashes Itself for Anti-Piracy Reasons (sneak peek)

A small anecdote of mine turns into a half hour of finding anti-piracy checks in Atari's Tempest. There are four of them, and they all check for different things and sabotage the game in different ways!

The Arcade Game that Crashes Itself for Anti-Piracy Reasons (sneak peek)

Comments

Yeah it's just shorthand (to save space mainly; I got it from the Asar assembler syntax). If you look at the bytecode for that bit of code, you'll see the same byte repeated four times, since each one is assembled as four separate instructions.

Nice video! One question: at 24:29, you show an `LSR #4` instruction to shift A right four times, but I didn't think that the 6502's `LSR` supports immediate addressing like that? Did Tempest use some 6502 variant, or is that just a shorthand for four `LSR A` instructions in a row? (And similarly for the `ASL #4` below.)


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