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The 386SX and 386DX were exactly the same silicon, but the cheaper model had a fuse deliberately blown to disable the maths coprocessor. It all comes down to wh
by timthorn 13y ago
The 386SX and 386DX were exactly the same silicon, but the cheaper model had a fuse deliberately blown to disable the maths coprocessor. It all comes down to whether you take the view that you're buying a piece of silicon, or a slice of R&D.
- Guvante 13y agoNote that sometimes this is done for partial failures, for instances if the tests for the maths coprocessor failed, they could just disable that bit and sell it at a lower price point. Historically that happened a lot more than today however.
- mjg59 13y agoNo, that was the 486SX/DX. No 386s had built-in FPUs - the 386SX was a DX with a 16-bit data bus and a 24-bit address bus.
- sageikosa 13y agoThe 386SX was a 16-bit data bus, the 386 was retroactively labelled 386DX to differentiate it. The 486SX and 486DX were the math co-processor variants of the 486, and they weren't originally "deliberately" blown; they just didn't pass QC and were disabled. Later variants just removed the sections for the FPU from the die.