In true Atari style they jumped on the IBM PC compatible bandwagon of the mid-80s
and produced some beautifully engineered machines - built in their own Fabs
and featuring pretty much no generic parts......of course this meant they were
more expensive than the IBM compatibles made by world+dog at the time so they
didn't sell too well.
The PC3 featured some impressive 80's styling and an Intel 8088 processor. I
also think this was the last Atari built PC, though there may have been a PC4.
After this came the PC5 and the ABC-PC, both of which were as generic as you
could get but with an Atari badge slapped on :)
Note the Atari logo stamped into the fan cover - they don't make 'em like that any more!