[TriEmbed] TriEmbed Digest, Vol 83, Issue 19

[Gregg Tracton]

> A lot of the video game hardware in the late 70’s/early 80’s didn’t have
a buffer to “draw” into. The Atari 2600 had (I think) 128 bytes of ram, to
draw the screen, developers had to time their code to be in sync with the
electron beam raster to draw!

> Fortunately there was an interrupt per scan line that did the timing for
> you. Most of the time you’d just copy the right RAM snippet into the scan
> line.
>
They also had Sprite’s, tiny (8x16 pixel?)  bit maps with hardware offset
> registers to position each sprite in the screen.  Those were automatic - no
> per-scan code needed - you just change the X and Y registers at the end of
> the screen scan to the sprites position in the next frame.  You could do
> the entire game of Pong with 3 sprites, writing only 6 bytes per frame to
> move the paddles and ball.  It was so easy to write games back then.
>
-- 
Gregg Tracton: tired, retired & inappropriately unattired (PJ's)
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