Date   : Tue, 16 Aug 1994 10:34:42 EST
From   : Stephen Quan <quan@...>
Subject: Re: i see basic! :-)

Chris Rae writes :
> SQ writes :
> > I tried a 256^2 loop (LDX #0 LDY #0 DEY BNE DEX BNE), and it took about
> > 30 seconds to run.  Oh geeze, that means I am 1/256 times slower, not 1/30.
> > Hmmrph, mumble, grumble.  ( :-) )
> 
> Hey, that's your maths playing up again!  ;-)

*sigh* yes it is slow.  You practically don't need screen paging via ^N
as the output is almost slow enough to be at human reading speed (for
a LIST or a *H.).

> > But, because of this and of other things I have done in my code, I
> > cannot run my emulator on anything less than a 386.
> 
> Hehe. Mine works on an 8086 (or at least it should... I haven't tried it 
> though!). What on earth else have you done that's 386-only?

I don't understand why, but my ASM code got too big to be inserted into
a Pascal program like yours, so I had to take it out and compile it using
a straight assembler.  When I did that the assembler said my JNZ, JC, ...
were illegal because the destination was outside -128..127 range.
Rather than re-engineering all my jumps (a relative jump followed by a
absolute jump) I switch the mode to .386 and the thing compiled again.

I suspect that if Borland finds that your jumps were out of range, it
will alter them for you.  I am not sure.

Anyhow, 6502 emulation is working fine, hardware support non existant
except for OSRDCH and OSWRCH hacks.  You are welcome to have a copy of
the source code if that will help you iron the bugs with your version.

As a matter of fact, anybody is welcome to have a copy of the prototype
(if they are interested).  The current requirements are :

    386 or above
    MS-DOS 3.3 or above
    64K conventional memory (maybe less)
    304K EMS memory (can use EMM386.EXE or QEMM)

I will be trying to setup anonymous FTP at my site to put it in.
-- 
Stephen Quan (quan@...                 )