Path: utzoo!news-server.csri.toronto.edu!rutgers!mit-eddie!mintaka!wookumz.ai.mit.edu!rjc
From: rjc@wookumz.ai.mit.edu (Ray Cromwell)
Newsgroups: comp.sys.amiga.emulations
Subject: Re: 8 methods to emulate a Z80
Keywords: Z80 68000 Amiga Emulator
Message-ID: <1991Mar11.180329.14211@mintaka.lcs.mit.edu>
Date: 11 Mar 91 18:03:29 GMT
References: <18847.27d80900@windy.dsir.govt.nz> <18850.27dbf20e@windy.dsir.govt.nz>
Sender: daemon@mintaka.lcs.mit.edu (Lucifer Maleficius)
Organization: The Internet
Lines: 15


  One method that might help to speed up your emulator is to recode
the spectrum rom into 68000 calls to AmigaDOS. I don't know if the
Spectrum is very i/o bound. For C64 emulators this doesn't provide
much improvement since most C64 programs, even productivety software,
bypasses the rom's. But for CP/M this is a great improvement. Charlie
Gibb's CP/M emulator almost runs at full speed! I'm serious. I have
a C128 with CP/M and my Cp/M emulator usually beats my 128 at
at unsqueezing/libraring programs.

 If IBM programs are I/O bound(they don't hit the hardware) an emulator
could go very fast. Unfortunately, this means writing MS-DOS and BIOS
in 68k code. I have also heard that alot of IBM programs poll
the keyboard, and bang on the serial port hardware directly. This
could be a problem.