Anon (no.delete@this.spam.com) on January 13, 2020 11:25 am wrote:
> Ricardo B (ricardo.b.delete@this.xxxxx.xx) on January 13, 2020 10:52 am wrote:
> > No, the 8-bit bus requirement was there because they were aiming at relatively low per unit marginal costs.
> > Without which the IBM PC, which was rather expensive as it was,
> > would have been even more expensive and maybe failed at market.
>
> More expensive by... $200?

Doubling the memory width would essentially double the cost of memory expansion so easily $200. Keeping the cost down would have required x2 or x4 memory chips and at the time, DRAM was mostly or all x1.

> I am pretty sure the development cost would be MUCH greater,
> the 8-bit bus allowed them to reuse some design.

The 8088 seamlessly interfaced to the existing 82xx series peripherals. The 8086 could also but not in an address compatible way without external logic. The way I remember it, the 8-bit peripheral needed a pair of external data bus buffers to drive both the low and high bytes of the 16-bit data bus depending on address bit A0 or just ignored it and drove both bytes with the same value. But a 16-bit access would return the wrong results so I wonder if that explains why the few 8086 PCs had obscure compatibility problems.