Re: emulator for Windows 3.1

[Mike Pfaiffer <mike@digitalcivilization.ca>]

mad ATARI user alternate wrote:
> where can i find an apple 2 / 3 emulator for Windows 3.1 ?

	You'll have to write/compile it yourself. Nobody has done it before. 
There are a lot of things to consider.

	Check out http://www.winehq.org (if the link doesn't work look for the 
wine project under google). You'll have to change the system calls to 
match those required by your machine.

	In addition, you'll need to work up an 80X86 emulator. It will have to be 
at least a 386 emulator. This is going to be tough taking the larger 
wordsize down to 8 bits.

	Even if you did get things working (no reason why they shouldn't), 
running Windoze programs on a //e or/// would be *SLOW*. They are slow 
on a 486/50 (my other PC). Take the speed of the program you are looking 
at on the PC and slow it down by the clockspeed. If you see it running 
on a 33MHz machine slow it down by 33 times. Then take into account the 
emulation. Let's be generous and say each instruction on the PC can be 
emulated on the Apple with 10 instructions. This makes it 330 times 
slower. Then there is the speed of the Windoze emulator. There *is* a 
reason I spell it Windoze. Emulating it on my Linux box results in the 
program running at 1/2 to 1/4 of the speed. Let's be generous again and 
say it will only slow down to half speed. This means if you decide to 
run a Windoze program on a stock Apple//e it will be 660 times slower 
than on a 33MHz PC.

	I forgot about memory. A full four Mb are necessary for a minimum 
installation. Add more for the 386 emulator and the programs. Fine for a 
GS but you'd need some fancy processing on the older machines. Again 
this would slow things down.

	Seriously, if you have a favourite Windoze program you'd like to see 
running on your machine... Disassemble it, look at the library calls, 
draw a flow chart for actions (and AI if necessary), then write it in 
6502 code. Then look for optimisations. You should be able to port quite 
a lot of programs and have them running at a reasonable speed this way. 
You'll also end up with something around 10% the code size.

				Later
				Mike



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