Atari ST Seven Bombs — Spurious Interrupt Crash

What Does This Error Mean?

Seven bombs is a 68000 'spurious interrupt' — exception vector 24.
The CPU received an interrupt request but no device claimed it.
Usually caused by faulty hardware on the bus: a bad cartridge, an unstable add-on, or a borderline RAM upgrade.
Power off, remove all cartridges and external hardware, then power back on.
If the bombs go away, you've found the culprit.

Affected Models

Atari 520ST
Atari 1040ST
Atari Mega ST
Atari STE
Atari Mega STE

Common Causes

Faulty cartridge inserted
Bad add-on board (Spectre, hard-drive interface, MIDI device)
Unstable RAM upgrade or socketed chip lifting
Marginal power supply
Failing IC on the motherboard

How to Fix It

Power off completely.

Don't just reset.
Switch off and unplug for 30 seconds so capacitors discharge.
Remove every cartridge and add-on.

Pull the cartridge from the cartridge port.
Disconnect any external hardware: hard drives, MIDI devices, modems, cartridges, the lot.
Boot the ST bare with just keyboard and monitor.
If it boots clean: add things back one at a time.

Power off, attach one device, power on, test, power off again.
The first device that reproduces seven bombs is the failure.
Repair, replace, or stop using it.
If it still crashes bare: look inside.

Open the case (after grounding yourself).
Press socketed RAM chips firmly back into their sockets.
Look for swollen or leaky capacitors, especially near the PSU.
Re-seat the keyboard ribbon cable.
Test with a known-good PSU.

ST PSUs from the 1980s are weak now.
If you have access to a known-good or modern replacement (PicoPSU adapter, recapped original), swap it in.
Many 'random' bomb crashes are dirty power.

Frequently Asked Questions

Is this the same as a regular crash?

No — most crashes are bus error (2 bombs), address error (3 bombs) or illegal instruction (4 bombs).
Seven bombs is rarer and usually points to hardware, not software.
Software bugs almost never cause spurious interrupts.