Date   : Mon, 15 Aug 1994 10:44:35 +0000
From   : lamcw <lamcw@...>
Subject: Re: Can I get BASIC going without BCD implementation?

"Chris L. Rae" <clr1@...> wrote:


;I now (at last) have "BASIC" coming up on the screen followed by three LF 
;codes and then my emulator conks out. I have a sinking feeling that this 
;could be because I have not implemented binary-coded decimal arithmetic.

nope, you don't need BCD to get the OS and BASIC working. just trap the
SED instruction to print a nasty message if it's ever executed.

;I havew a bit of a problem which I'd appreciate if someone could solve. I 
;have put the BASIC ROM in at &8000 as recommended and not yet supported 
;ROM paging via &FE30. However, during execution the O/S puts &F into 
;&FE30 (is that paging in BASIC?

i've found you don't need to implement &FE30.

;> The source code is in C and has a lot of similarities with James B
;> compiler, and without his help, Chris Lam and many others on this
;> discussion list I wouldn't have got this far.  The emulator is
;> running dismally slow under MS-DOS on a 386DX-33 and 'feels' slow on
;> a 486DX2-66.  On a 386DX-33 it is operating at about 30 times slower
;> than a real beeb.

;30 times slower?!? That's pretty awful (no offence)! I would have thought 
;that even a C version would be a bit faster than that. Although I have 
;yet to get BASIC going, I would have thought that it would go no slower 
;than about 1/2 Beeb speed. However, I might retract that when I get it going!

i'm not surprised because SQ has only just got his prototype working. my
one was just as slow to begin with. but with patience and ingenuity, you too
can get REAL beeb speed just like my C version! (moving to faster machine
also helped!!!)

these 486DX2-66 PCs are s'posed to be fast aren't they? 

chris lam,
aston uni,
uk.