Re: Applesoft BASIC

[Jerry <blip_awanderin_blip@blipyahoo.ca>]

Mark Percival wrote:
> Bryan Parkoff wrote:
>
> >    I notice what I read documents on the Google search.  It says to use $69
> > and $6A.  I don't know what this is for, but Mark recommends to use $67 and
> > $68.
>
>
> $67-$68 = Applesoft text table pointer (Points to the beginning of
> program text
>                 default value $0801)
> $69-$6A = Applesoft variable table pointer - points to the start of
> simple variable
>                 space (at the end of Applesoft program text)
>
> Source: What's Where in the Apple? By William F. Luebbert
>
> -- Mark

Also, when you change $67-$68 (103-104), you have to poke a zero at the 
address prior.  So for starting your program at $4000:

  POKE 103,1
  POKE 104,64
  POKE 16384,0
  NEW

  or

  RUN PROGRAM-NAME

Applesoft will complain if there is not a zero in the location prior to 
($63,$64).

If your program fits between $801 and $1FFF, but its variables do not, 
start your program with LOMEM: 16384 (if you use HGR), and then you do 
not need the POKE trick above.

See page 127 in the Applesoft II Reference Manual.  It has a memory map, 
along with the zero-page locations that control where it stores what.




--
Jerry Penner     e-mail:  remove the blips and _