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Technology Stocks : Intel Corporation (INTC) -- Ignore unavailable to you. Want to Upgrade?

To: Tony Viola who wrote (39989)	11/11/1997 12:40:00 PM
From: Petz	Read Replies (2) \| Respond to of 186894

Test your system for the Intel F0 bug. 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 and an AMD K6-233. I got an illegal opcode exception, exactly at offset 100 as expected, but Windows 95 kept humming along. On Intel Pentium and Pentium MMX CPU's you go into an infinite loop and nothing save turning off power will get you out. Anyone tried this on a Tillamook yet? PS, don't do this while anything else is running which could cause a disk access. Petz

To: Tony Viola who wrote (39989)	11/11/1997 12:54:00 PM
From: Petz	Read Replies (1) \| Respond to of 186894

Tony, RE: Bugs like this are found in mission critical system 390 and other large scale computers to which companies like Ford, Daimler Benz, AT&T, EDS, and other multi-billion dollar companies commit their entire operations They are NOT. The IBM 360 series and its followons had a much more regular instruction set where the opcode is completely defined in the first byte. This is totally unlike the x86 architecture which has grown out of control with bits all over the place defining new instructions for each new generation. The problems are fixed almost always by microcode patches. If such a bug were found on a mainframe, you are right, the microcode would be patched by replacing a PROM. On an Intel CPU this is totally impossible -- the microcode is embedded in the silicon. A software patch to scan for the 4-byte sequence is also totally inadequate because any hacker could write a program to generate the code one microsecond before executing it. *Intel's only recourse is a recall.* Petz