24 Jan
2013
24 Jan
'13
12:49 p.m.
On Thu, Jan 24, 2013 at 3:36 PM, David Riley <fraveydank at gmail.com> wrote:
On Jan 24, 2013, at 1:42 PM, Fred Cisin <cisin at
xenosoft.com> wrote:
He may be talking about the AMD second-sourced 486SX, which may have
had a different method of disabling the FPU. My recollection is that
the 486SX was, in fact, the same die as the 486DX (FPU and all) with
a fuse blown that disabled the FPU.
Back in the day, I heard the FPU was "disconnected" with laser-drilled
holes on dice that failed FPU testing, then the package was labelled
to match. To be clear, a wafer was made up of dice that were intended
to be sold as 486DX chips but failed FPUs (and most likely enough ones
with good FPUs to cover customer demand) were pierced.
I can't promise what I heard then was true, but it was commonly
reported as such. It's possible that they did that at first, then
after a die shrink split the lines into straight 486DX and 486SX
wafers and discarded any that failed any test. At first, though, I
find it believable that yields were low enough to want to sell any
parts they could (since retail prices were many hundreds of dollars
per CPU back then).
-ethan
debacle,
there was software thatcould
completely restore functionality.I think it was called above-board,
NOPE.
which had hardware as well as software,but on
many SX type systems it
was just software Actually if I remember correctly it was the 486SX CPUs
made by AMD
We are talking INTEL.