Again, wrong software in BIOS is not and does not create hardware
damage. Re-flash the BIOS and computer works just fine. Many
computer BIOS can be reflashed without vendor assistance. But again,
we are discussing sufficiently designed hardware. Cost of repair is
also completely irrelevant. The point: hardware is not damaged;
nothing burned up. Remember Mike's original question:
> Consider a hypothetical computer virus that would cause a
> CPU to overheat and burn up. Is this possible?

Virus may also damage Operating System. Cost of damage would be much
higher. Repair may means hundreds of dollars for a disk recovery
service. This virus damage also is not hardware damage. Virus cannot
burn up CPU. Hardware design means a virus cannot damage hardware.

'Overheat signaling' does not involve software. If processor
overheats, then processor automatically throttles back or shuts down -
a hardware function completely independent of software. Signaling is
not accessible by 'machine code' in a virus. Overheat protection and
other hardware functions are implemented in hardware. 'Machine
code' instructions (from virus or other software) cannot damage
hardware if machine is properly constructed.

What happens when wrong HAL layer gets loaded for Windows NT
operating system? 'Machine code' instructions are loading wrong values
in registers. Will hardware be damage? Of course not. Hardware will
not operate; may even require expensive assistance. But again,
'machine code' instructions do not harm hardware. Defined is how
hardware engineers design products. Hardware defines what software
(virus or Operating System) can and cannot do. No hardware engineer
would intentionally design hardware that user software (virus or
Operating System) can damage. Legacy in today's computers (why we
don't design whole new computers from scratch) are why hardware
design is so software resilient.

Sebastian Gottschalk wrote:
> w_tom wrote:
>> But again, what can change in the Flash BIOS? It can change
>> insutructions (machine code) for the processor to execute. But does
>> that cause damage?
>
> The computer won't boot again, and without proper procedure (recovery flash
> from a pre-prepared floppy disk in a floppy drive), a repair will be
> needed. Flashing the firmware of various drives and cards requires repair
> from the vendor itself, so yes, this is a costly damage.
> ...
>
> IBTD. Just disable the overheat signalling.