3 ms·
Most extreme trick was destruction code, which would only be executed while debugging, due to timing. Back than it was possible to destroy CRT display (set refr
by jkot 11y ago
Most extreme trick was destruction code, which would only be executed while debugging, due to timing. Back than it was possible to destroy CRT display (set refresh frequency too high), motherboard (overwrite BIOS) or harddrive.
- jacquesm 11y agoOne particular nasty trick was a very tight loop with interrupts disabled writing 0 to a location that was 0xff in the ROM. The ROM and the CPU would end up fighting over this, it effectively shorts 5V through the databus drivers to ground. The goal here is not to damage some peripheral but to directly damage the CPU. On more modern CPUs this trick should not longer work but on quite a few 8 bit micros it definitely did (let's not go into how I know this and how I know the ca. 1987 list price of a 6809).
- kuschku 11y agoTime for a lawsuit, I guess? Debugging is your right, and destroying your hardware is not something the software may do.
- jacquesm 11y agoI think you replied to the wrong person.
- kuschku 11y agoWell, you wrote about software you used trying "to directly damage the CPU." That definitely sounds like malicious intent from the devs.
- jacquesm 11y agoI was the dev, checking if this was actually possible. And - much to my surprise I might add - it was.
- kuschku 11y agooh, interesting. Still, it’s not really a great idea to damage your users’ systems. Liability and everything. ---------------- EDIT: Due to HN blocking me from posting new comments, I’ll answer here: Yes, I’m sorry, I had originally thought you were talking about the same as the parent you replied to: Software that tries to physically hurt your system when you try to debug it. We can only be lucky that that isn’t possible today anymore, considering the fact that malware is widespread by now, it’d surely have used a "pay 20$ or your PC is dead" scheme otherwise.
- jacquesm 11y agoThe system was my own.
- beagle3 11y agoSo, you're saying that the mythical HCF instruction[0] was somewhat real? [0] https://en.wikipedia.org/wiki/Halt_and_Catch_Fire https://en.wikipedia.org/wiki/Halt_and_Catch_Fire
- jacquesm 11y agoYes, but it was more like 'loop and burn out a transistor'. No fire and no visible damage, just a cpu that wouldn't work any more. I didn't try it again to see if it was reproducible, it was a lot of money for me at the time and I considered myself pretty dumb for trying. A sample of '1' was enough to prove the point for me. I wished I recalled what drove me to try it, I'm fairly sure it was some outside influence, not something I came up with by myself and wondering 'what if'. More like: that's never going to work, here, let me show you. (Famous last words...)
- 0x4a42 11y agoI remeber the CIH virus used to break motherboards by corrupting the BIOS.