3 Bombs (Illegal Instruction)
Atari Atari ST
Severity: CriticalWhat Does This Error Mean?
Three bombs on an Atari ST means an Illegal Instruction — the CPU tried to execute a binary opcode that is not a valid 68000 instruction. This typically happens when the CPU accidentally jumps into data instead of code. Reset the machine.
Affected Models
- Atari ST
- Atari STF
- Atari STE
- Atari Mega ST
- Steem emulator
- Hatari emulator
Common Causes
- Program counter jumped into a data area and tried to execute it as code
- Stack overflow causing the return address to point to garbage
- Software compiled for 68020 instructions being run on a 68000 ST
- Corrupt program file — missing or scrambled bytes in the executable
- Copy protection scheme that intentionally uses illegal opcodes, misconfigured
How to Fix It
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Reset the machine — three bombs is always a fatal, unrecoverable crash.
Press the reset button on the right side of the ST case.
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If this happens with a specific game or program, check the TOS compatibility.
Some software was compiled with 68020 instructions for accelerated STs. Running it on a stock 68000 machine triggers illegal instruction errors. Check whether the program requires an accelerator.
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Verify the disk or file is not corrupt.
A corrupt .PRG or .TOS file may have garbled bytes in the code section. Re-download or re-copy the program from an original source.
Frequently Asked Questions
What is the 0x4AFB opcode that some ST programs use intentionally?
0x4AFB is one of the officially illegal 68000 opcodes that some copy protection schemes used deliberately. The expected behaviour was to trigger an illegal instruction exception, which the protection code trapped to verify authenticity. On hardware or emulators that handled it differently, crashes occurred.
Can a 3-bomb crash damage the Atari ST?
No. Bomb screens are purely software crashes — the hardware is unaffected. A reset returns everything to normal. The only risk is losing unsaved work in any open program.