A 1980s BASIC game hid machine code inside a comment. It took 40 years to explain why (beej.us)
A cryptic REM comment opening a 1980s dungeon-crawler BASIC game turned out to be raw Z80 machine code, not text — planted at the precise memory address a USR() function call expected to execute from.
The trick exploited how the Exidy Sorcerer's BASIC interpreter tokenized and stored source in RAM — the comment's bytes landed exactly where executable code needed to sit, disguised as an unreadable remark.
The payload itself did something clever: read the Z80's ever-incrementing R register as a cheap source of randomness for the game's random number seed, decades before hardware RNG chips were common.
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