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From: gson@niksula.hut.fi (Andreas Gustafsson)
Newsgroups: comp.sys.handhelds
Subject: Re: CHIP48 - A CHIP-8 interpreter for the HP48SX (version 2.20)
Keywords: HP48SX CHIP-8
Message-ID: <1990Sep15.094349.15174@santra.uucp>
Date: 15 Sep 90 09:43:49 GMT
References: <1990Sep3.161605.14532@santra.uucp> <1990Sep11.190440.6069@agate.berkeley.edu>
Sender: news@santra.uucp (Cnews - USENET news system)
Reply-To: gson@niksula.hut.fi (Andreas Gustafsson)
Organization: Helsinki University of Technology, Finland
Lines: 17

moews@math.berkeley.edu (David Moews) writes:
> Does anyone know how fast this interpreter is, compared to the original
> one running on a 1.78 MHz 1802?

I haven't run any actual benchmarks, but they appear approximately
equal.  A 1.78 MHz 1802 is about 0.11 MIPS.

In the 1802 interpreter, the DXYN instruction waited for for the next
60 Hz interrupt in order to synchronize drawing with the display
refresh.  CHIP48 tries to emulate this behaviour by waiting for the
next 64 Hz timer increment, so most games run slightly faster on the
HP48SX.  Removing this synchronization causes typical programs such as
BRIX to run perhaps twice as fast, in both implementations.
-- 
Andreas Gustafsson
Internet: gson@niksula.hut.fi
Voice: +358 0 563 5592