OT - 486 w/newer IDE drives
cclist at sydex.com
Thu Nov 23 14:59:54 CST 2006
On 23 Nov 2006 at 14:01, Tothwolf wrote:
> Actually, the early 486SX dies were fully working 486DX parts. They just
> had a different pinout and no bond wires were installed for the FPU. Intel
> did ship later 486SX chips that were made from dies with defective FPUs.
As I understand it, Intel on the early -20 486s had a yield problem
with the FPU circuitry. So the 486sx was born. NMI* was moved from
B15 to A15 and and FERR* and IGNNE* weren't bonded out. Later 486s
(the -25 and -33) had no NDP on the die.
The 487 has the same pinout as the 486DX with the exception of
bringing MP* out to B14 (nc on the 486SX) and FERR* out to A13. As I
understand it, the 487sx was essentially a fully-functional 486DX
under the clay.
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