Re: writing to POST leds?

Edward Welbon (
Sun, 8 Sep 1996 21:42:55 -0500 (CDT)

On Sun, 8 Sep 1996, Leonard N. Zubkoff wrote:

> I have one of these also.

What kind do you have? I had to hack mine up to the LEDs to show up in
the front i.e., desolder the LEDs from the ISA board (you are supposed to
look at the board to use it in the shipped form), solder in a ribbon cable
into the resulting empty pin-holes(via's) and then hack up the clock led
baord etc.. it works well enough but it is an ugly hack.

> It's useful for debugging device drivers


> However, the SLOW_DOWN_IO code in
> asm/io.h writes random values to port 0x80, which tends to obscure the values
> written by users.

Oh yeah... Darn. Is this necessary? Can I change these calls back to the
jumps or maybe to another address? How about a read CPUID, that is
synchronizing and should slow down things nicely (though it does change a
register... uk, never mind)? Would a write back invalidate of the
current instruction L1 cache line be OK? That should cause a nice slow

Ed Welbon;;