Re: Crosspost: Did the cpu influence the display?

["Bill H" <bill@ts1000.us>]

Peter van Merkerk wrote:
> Bill H wrote:
> > ===========================================================
> > This message has been cross-posted to a number of revalent usenet
> > groups, so please do not start a "My system is better than your system
> > flame war".
> > ===========================================================
> >
> > Relying on my memory and a cursory check on a number of websites it
> > appears that the majority of Z80 cpu based computers had black and
> > white displays, where as the majority of 65xx computers had a color
> > display.
>
> I don't think that is true, at least not for home computers.
>
> There are plenty of (early) 6502 based system which supported only B/W
> display, and there are also plenty of Z80 systems which supported color
> (ZX Spectrum, MSX, Amstrad CPC, Sharp MZ series, Enterprise...etc).
>
> If we include CP/M computers (which are Z80 based) then what you are
> saying might be true. However those where intended for business use. In
> those days color was not deemed to be important for business computers.
>

I probably should have specified a time period. I was thinking more of
the 78 - 82 time period and computers that were available for home use
mainly in the US (only because that is where I am and have the most
experience with). During that time period the popular computers on the
Z80 side where the Tandy's (and clones), the zx81, ts1000 and some CP/M
machines. On the 65xx side where the Apple ][s, Atari's and Commodores.

> > Now there are exceptions to this, but it makes me wonder, did the CPU
> > influence the display?
>
> There is no technical reason for having a correlation between color
> support and the CPU.
>
> > Is there an inherent reason why most Z80 computers had b/w displays and
> > 65xx computers had color?
>
> I don't think that statement is true, so the answer is no.
>
> > You may think it would have been cost, b&w would be cheaper than color,
> > but in the majority Z80 computers where more expensive than 65xx
> > computers.
>
> I doubt that is true either. For example the Sinclair ZX Spectrum was
> significantly cheaper than most 6502 based systems, and did support color.
>
> > Now it could have been display size, many Z80 computers used 80 columns
> > which is hard to achieve when using a TV as a monitor. But on the other
> > hand, with color you need more memory to achieve a good working
> > resolution.
>
> See my remark at the beginning.
>
> > So the question is, did the cpu influence the display?
>
> No, at least not whether the system supported color or not. Of cource
> the CPU is one, but not the only, factor that affects how fast a display
> can be updated, but that is another story.

One reason I was thinking that the cpu could influence the display is
that z80 had a larger instruction set that allowed you to do more with
the cpu than the 65xx. So on the 65xx side you needed more support
chips to do things that the cpu could not.

For example on a 65xx would it be possible to drive the display as is
done on the zx80 (not the ts1000 or zx81 which used a custom chip) and
the cpu with only a few off the shelf logic chips?