Re: Any way to pause an EXEC?

["Michael J. Mahon" <mjmahon@aol.com>]

Michael J. Mahon wrote:
> Jayson Smith wrote:
>
> > Hi,
> > There are several PRINT CHR$(4), things in the program being cracked.
> > Here's what my EXEC does
> > NEW
> > write program to prompt user for disk
> > This part is working perfectly.  Then...
> > LOAD PROGRAM1
> > do the crack
> > SAVE PROGRAM1
> > LOAD PROGRAM2
> > do the crack
> > SAVE PROGRAM2
> > PRINT "DONE."
> > As soon as program1 loads the EXEC stops and leaves me at an Applesoft
> > prompt.  This does not happen when the two programs are nonexistant on 
> > the
> > disk, the already written program is simply saved twice under two 
> > different
> > names since the LOAD attempts fail.
>
>
> Since LOAD and SAVE implicitly work on the current Applesoft program,
> you cannot use them *within* an Applesoft program--for example, LOAD
> changes the Applesoft program pointers.
>
> You will need to BLOAD and BSAVE the Applesoft programs to avoid
> changes to the program pointers, and you will have to move your
> "control" Applesoft program to a region of RAM not overwritten
> when these programs are BLOADED to $801 (the standard Applesoft
> load address).
>
> In short, this is much more complicated to do than it seems.

I shouldn't have responded to this while jet-lagged.  ;-)

The solution I proposed, is, of course, a ProDOS solution.  ProDOS
allows you to BLOAD any file type as long as you specify it explicitly
along with the load address.  You can BLOAD/BSAVE an Applesoft program
to/from any address, but you have to PEEK the file length so you can
specify it in the BSAVE (if you change it).

This means that the controlling BASIC program can run in the normal
($801) location, but needs to do the BLOADs and BSAVEs from a location
that 1) doesn't interfere with it or its variables, and 2) allows
enough space to fit the program being manipulated.

I don't know any straightforward way to do this under DOS.

-michael

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