Why can't certain colors go to some pixels?

[ronb@cc.usu.edu (DR TE$TH & THE ELECTRIC MAYHEM)]

It has been about 6 years since I even thought about apples, but while working
on my ray tracer, I realized that when I was a kid, I had all of the facilities
to do something similar on my ][E.  The thought occurred to me however, that
the ][e did not allow you to write certain colors to certain pixel positions. 
Does anyone out there have a technical explanation for why this was the case?

	rOn

--
DISCLAIMER - These opoi^H^H "dang", ^H, [esc :q :qq !q "NYRGH!" :Q! "Whaddya
mean, Not an editor command?" :wq! ^C^C^C !STOP ^bye ^quit :quit! !halt ...
^w^q :!w :wq! ^D :qq!! ^STOP [HALT!   HALT!!! "Why's it doing this?" :stopit!
:wwqq!! ^Z ^L ^ESC STOP  :bye  bye  bye! M-X-DOCTOR "HELP! I can't get out of
this stupid editor!!!" And how does this make you feel?