Adrian (a.delete@this.acm.org) on January 9, 2020 9:15 am wrote:
>
> ...
>
> I doubt that the fact that most Z80 improvements were also present in 8086 was a coincidence. It
> was most likely intentional, because until the early nineties, when Intel finally became comfortably
> ahead of its competitors, most new features added to every generation of Intel CPUs were present
> earlier in competing CPUs from Motorola or others, but Intel was quick to add them too.

I agree that it was no coincidence but I do not think the Z80 improvements were included on the 8086 for backwards compatibility. Intel knew what they had to compete with and that the Z80 would have higher performance 16 bit successors, which it did although way too late for IBM to consider them.

> For most programs that I have used initially on MS-DOS, I had previously used a version of them on CP/M.
> For example I had used a large number of compilers and interpreters from Microsoft and also WordStar and
> other programs that I do not remember now, in their CP/M variants, before using them as MS-DOS programs.
>
> So I have no doubt that porting programs from CP/M on 8080/Z80 to MS-DOS
> on 8088/8086 was very important in the beginning and that many might have
> used the assembly language translators, at least for an initial version.

The only common program other than development tools that I used on CP/M was Wordstar and I am pretty sure the initial MS-DOS Wordstar was translated. Later I used the spreadsheet Microsoft Multiplan, which was pretty horrible, on CP/M but I never saw that on MS-DOS.