> I know, they didn't have address pins on the 40-pin package. You are right that doesn't have to be a limitation on internal architecture: The 386SX internall

> I know, they didn't have address pins on the 40-pin package. You are right that doesn't have to be a limitation on internal architecture: The 386SX internally had the 386's 32-bit data bus only 24 bits were carried out to the external pins. This, along with squeezing the 32-bit data lines through a 16-bit data bus by doubling up requests, made it able to be used on cheaper motherboards based on 286 designs. I'm not sure that this would have made enough difference to be worth the cost of the extra silicon at that time of the 8086's design though. While a flatter and more roomy address space would have been convenient to developers there would be little or no benefit for end users. The 386SX was a success because it could run software intended for the original 386 (then renamed 386DX) on cheaper hardware (and had the same MMU allowing virtual memory so could run larger software then it's 16Mb physical RAM limit made possible, at a further performance cost). Also the extra silicon requirements were not as expensive at the time the 386SX was being designed as when the 8086 was. In fact there was a chip that did similar for the 8086: the 8088. It had an 8-but external address bus and broke up 16-bit requests to make them over it. Though unlike the 386SX it maintained the same address bus of its relative.