How compatible were "MS-DOS Compatible" machines?

[Jim Leonard]

scheefj at netscape.net wrote:
> In the early 8088/86 days, manufacturers like DEC, HP, TI and Zenith 
> thought they could compete with IBM by being "better" in some way. 
> Zenith had 640x400 graphics and did the Tandy 2000. 

As did the AT&T PC 6300/Olivetti M24.  It CGA but with a 400-line 
monitor and 32K instead of 16K display RAM.  It could do 640x400 in 2 
colors.  Once nice side-effect of having that much RAM is that it 
unintentionally gave CGA 2 true video pages -- but since having only one 
page normally was an exploitable trick, such games that used the trick 
didn't display properly on the 6300.

A later "Display Enhancement Board" (DEB) upped that to 16 colors with 
palette capabilities, and also allowed the onboard CGA to mix with the 
DEB graphics, allowing mixing graphics with text.  I never once saw 
commercial software exploit this :-(

> So to the original question -- the three requirements will limit the 
> program to "true compatibles", meaning a hardware clone. The most 
> incompatible MS-DOS machine ever, the Seattle Gazelle, uses a serial 
> terminal so the only "sound" available would be the terminal bell.

LOL

Thanks for the advice.
-- 
Jim Leonard (trixter at oldskool.org)            http://www.oldskool.org/
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