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To: Dief who wrote (2054)11/11/1997 2:33:00 AM
From: Petz  Read Replies (3) | Respond to of 6843
 
Dief, the F0 bug is worse than I thought.

If you want to demonstrate the bug do this:
1. Go to a DOS prompt and type EDIT, to start the MSDOS editor
2. Hold down Alt key, type 240 on the numeric keypad, lift Alt key
3. Hold down Alt key, type 015 on the numeric keypad, lift Alt key
4. Hold down Alt key, type 199 on the numeric keypad, lift Alt key
5. Hold down Alt key, type 200 on the numeric keypad, lift Alt key
6. Select File, Save using the mouse, enter filename of xx. Exit EDIT.
7. Type DEBUG xx (starts MSDOS DEBUG program)
8. Type d followed by <Enter> and you should see the killer sequence F0 0F C7 C8 in the first four bytes.
9. Type g then Enter. If your machine is a true blue P5 nothing will happen and your system will have to be powered down.

I have a Cyrix M1-120 MHz. I got an illegal opcode exception, exactly at offset 100 as expected. Presumably on Intel CPU's you go into an infinite loop and nothing save turning off power will get you out.

I'll try this on my K6 at work tomorrow and try to get some Pentium users to try it.

PS, don't do this while anything else is running which could cause a disk access.

Petz