PDP-1 (was Re: Christie's auction)

From: Eric Smith <eric_at_brouhaha.com>
Date: Tue Feb 15 18:07:05 2005

woodelf wote:
> Now that they got Spacewar... How about getting somthing like
> 'space-invaders'.

Volunteering to write one? :-) If you write it, we'll run it.
I've been using the cross assembler that is part of Bob Supnik's
SIMH package:

> I was thinking somthing that uses the character generator on
> the vector display would be nice too.

It's only a point-plot display, unfortunately. No vectors, and
you can only display a fairly limited number of points before
noticable flicker sets in. Points take nominally 50 us each to
plot, so if you want 20 Hz refresh, you only get 1000 points to
work with, which isn't enough for very many software-generated

I'll try to get a simple character generator test program written
and running tonight. The nice thing about it is that the
character set is completely programmable. Pretty nice for a 1961
computer, huh? :-)

Of course, the reason it's programmable is that software has to
supply the 5x7 bitmap for each character when it wants to display

The characters take just as long to display as the number of plotted
points in them, so it is faster than drawing them one point at a
time in software, but not blindingly fast.

Received on Tue Feb 15 2005 - 18:07:05 GMT

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