ALife sims and terminal refresh rates (was Stupid eBay user du jor)

Philip Pemberton philpem at
Mon Feb 27 04:58:56 CST 2006

In message <m1FDSKS-000IyVC at p850ug1>
          ard at (Tony Duell) wrote:

> > I wonder how fast I can refresh an 80x24 VT display over a 19200 Baud RS232
> > link...
> Well, if you hae to re-write the entire screen each time : 
> 19200, assuming 10 bits per character (start, 8 data, 1 stop) is 1920 
> characters/second. Your screen has 1920 characters. So one full screen 
> per second, maximum

So not fast enough to get 2fps on an Alife simulator. Drat.
Looks like I need to make my homebrew LCD controller 6502-bus-compatible
then. 480x256 monochrome - it's not much, but it should work pretty well. It
would be even nicer if I could get Hitachi to give me a copy of the specsheet
for the SP21H002-Z1A display. I've been told it's a 640x200 RGB display with
a touchscreen, but nobody seems to have a specsheet and all the controller
chips are chip-on-glass. The sales guy at Hitachi can't even be bothered to
either return my calls or reply to the email I sent... natch.

> second. In fact the PERQ easily beat it -- the peak speed, assuming all 
> you were doing was displaying things on the screen, was nearer 10 full 
> screens per second, and that's a full PERQ secreen, which displays 
> something like 80*66 characters.

Wow. Not bad. That said, the VRAM would have been memory-mapped, so I would
have expected a decent write speed anyway.

Phil.                         | Kitsune: Acorn RiscPC SA202 64M+6G ViewFinder
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