Groups > comp.sys.apple2.programmer > #212

Re: Best place to hide about 30 bytes in //e RAM

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From	"ict@ccess" <gids.rs@sasktel.net>
Newsgroups	comp.sys.apple2.programmer
Subject	Re: Best place to hide about 30 bytes in //e RAM
Date	Sat, 3 Mar 2012 18:47:25 -0800 (PST)
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On Mar 3, 9:41 am, Egan Ford <dataj...@gmail.com> wrote:
> Programmers,
>
> I just created a program launcher that I'd like re-activate on
> CTRL-RESET.  I know that I have no control over the programs being
> launched and that there will be a chance that my reset vector bytes
> ($3F2-$3F4) may get hosed, but in the event they do not, where is the
> least likely place someone will use memory?  I tried page $BF with the
> worse results.  Right now I am starting at $310 with good results, but
> I'd like better results if possible.
>
> Thanks.
>
> P.S., I should mention that this is for the //e only.  The main program
> is in AUX memory, my reset routine on CTRL-RESET copies back to main
> memory.  I cannot run from AUX memory since I use self-mod code and need
> a fresh instance on restart.
>
> Thanks again.

Since you mentioned $BF, I gather you are using Prodos.  Are you using
Basic.system?
Do you still need your reset program to be safe in memory when you run
system programs?

So why not install your 30 bytes between Prodos and its buffers.

LDA #1
JSR $BEF5

The accumulator is returned with the high byte of the address where
free memory has opened up.

I have a whole page of different subroutines that I install there when
I run basic.system, so very little memory is wasted.  Anything from
keyboard shortcuts to a short program to allow the <delete> key to
work ... etc etc

OR

put your program launcher in place of the BYE routine in Prodos.  This
way any system, binary or applesoft program has access to it, since
Prodos is always in memory.

Rob

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Thread

Best place to hide about 30 bytes in //e RAM Egan Ford <datajerk@gmail.com> - 2012-03-03 07:41 -0800
  Re: Best place to hide about 30 bytes in //e RAM Steven Hirsch <snhirsch@gmail.com> - 2012-03-03 14:10 -0500
    Re: Best place to hide about 30 bytes in //e RAM Hugh Hood <hughhood@earthlink.net> - 2012-03-04 17:55 -0600
      Re: Best place to hide about 30 bytes in //e RAM Hugh Hood <hughhood@earthlink.net> - 2012-03-04 17:57 -0600
        Re: Best place to hide about 30 bytes in //e RAM Egan Ford <datajerk@gmail.com> - 2012-03-05 08:55 -0700
  Re: Best place to hide about 30 bytes in //e RAM Antoine Vignau <antoine.vignau@laposte.net> - 2012-03-03 12:53 -0800
  Re: Best place to hide about 30 bytes in //e RAM "ict@ccess" <gids.rs@sasktel.net> - 2012-03-03 18:47 -0800
  Re: Best place to hide about 30 bytes in //e RAM Egan Ford <datajerk@gmail.com> - 2012-03-04 11:33 -0700
    Re: Best place to hide about 30 bytes in //e RAM "ict@ccess" <gids.rs@sasktel.net> - 2012-03-04 19:19 -0800
      Re: Best place to hide about 30 bytes in //e RAM Egan Ford <datajerk@gmail.com> - 2012-03-05 08:56 -0700
        Re: Best place to hide about 30 bytes in //e RAM Antoine Vignau <antoine.vignau@laposte.net> - 2012-03-05 14:25 -0800

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