gallier2 (gallier2.delete@this.gmx.de) on October 6, 2021 11:06 pm wrote:
>
> >
> > Starting with the IBM PC/AT, i.e. with 80286 or better CPUs, the CPU had the instructions
> > INS & OUTS, which could transfer data much faster and much simpler than 8237.
>
> nitpick, 80186 introduced INS and OUTS.
>



80186 and 80286 were launched simultaneously in February 1982.

So both introduced INS and OUTS at the same time.

I have mentioned only 80286 because the discussion was about 8237.


8237 was used together with 80286 in IBM PC/AT, but it was discovered immediately that using INS & OUTS for transferring data with the hard-disk controller was faster than using 8237 for that task.

80186 was not used in any IBM PC. There were a few PC/XT clones with it much later, but PC/XT clones normally used the cheaper AMD 8088 or the faster NEC 70108.

80186 in a PC/XT clone was a bad choice because it was used only partially. For example it had a better internal DMA controller than the external 8237, but in a PC/XT clone that could not be used due to software incompatibility.