Re: Garbage Collection

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <ddoms-1403951423520001@ttyqd.tyrell.net>,
Dennis Doms <ddoms@tyrell.net> wrote:
>
> Briefly (and if my own memory serves correctly), protected memory is
> memory above (Applesoft and/or BASIC.System) HIMEM, below LOMEM, or marked
> as used in the ProDOS system bitmap.

Under BASIC.SYSTEM, the bitmap is used to protect pages 0 and 1
(zero page, stack), the text screen (pages 4 to 7), and all of
BASIC.SYSTEM's code from $9A00 to somewhere around $BDFF.  I seem to
recall that there is one unmarked page near the top of BASIC.SYSTEM,
but its global page (and ProDOS's global page) are marked as protected.

The system bitmap is not affected by HIMEM or LOMEM - you can BLOAD or
BSAVE anywhere within the $0800-$99FF space, unless the area is in use
as a file buffer.  In particular, if you use the GETMEM call to
reserve some pages, they will not be marked as "protected" in the
bitmap unless you do it yourself.
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand