Re: Most Difficult Emulator

[kauai96765@yahoo.com (The Apple Man)]

mjmahon@aol.com (Michael J. Mahon) wrote in message news:<20020901235159.25665.00001002@mb-md.aol.com>...
> 
> Bryan, while I must admire your enthusiasm, I wonder what you are thinking.
> 
> PC emulators for the various Apple II machines are pretty well developed.
> And the speed of x86 platforms is such that the problem with emulators is
> that they are too fast, if anything.  ;-)  There is no practical need for a
> faster
> emulator on the PC platform.
> 
> If you would like to write one to gain experience, I certainly understand that.
> If you plan to use object code translation as an emulation mechanism, the
> project will be very challenging and educational.  You will learn that all of
> the 6502 code must be kept around, since some of it is _data_ and some
> programs will simply not work if they cannot reference their 6502 code
> stream--and even _change it on the fly_.  These problems can be detected
> and dealt with, but the net effect is that it is much more difficult than you
> may think to create a fully compatible Apple II emulator based on object
> code translation.  (And, as I mentioned, additional emulation speed is
> not actually a very high priority at the present time.)
> 
> When you opened with the statement that "It takes couple seconds to read
> 6502 opcode table before it emulates into 80x86 opcode.  It can cost a lot
> of time."--I don't know what you are referring to.  The emulators that I am
> aware of simply index into an opcode table or CASE statement table, and
> that operation takes a negligible part of the emulated execution time.
> 
> -michael
> 
> Check out 8-bit Apple sound that will amaze you on my
> Home page:  http://members.aol.com/MJMahon/

Bryan,

I must add my 2 cents and say i also back what Michael said.  The
emulators on the average Pentium III machine is so fast that you have
to slow it down to normal speed (Most of them do have speed controls
for this).

However, where I depart from the agreeing is that there are half a
dozen good emulators which could be written but have yet to have
appeared. (I am too involved in my hardware to do one).  No one has
written a //gs emulator for the pocket PC yet.  There is a //e
emulator which is quite good and is also nice and fast.  If you are
looking for a challenge, try that one first.