a2d/desktop/README.md

# DeskTop diassembly notes

## DESKTOP.SYSTEM

A short (8k) loader program. This is likely responsible for copying
the rest to a RAM card (if available), then invoking the main app.

## DESKTOP2.$F1

This is large - 111k. It includes a loader, the DeskTop app (with both
main memory and aux memory segments, filling everything from $4000 to
$FFFF (except for I/O space and ProDOS), and still having more code -
probably the disk copy code which is swapped in dynamically.

The file is broken down into multiple segments:

* segment 0: load - offset $0000, length $0580, loaded at $2000
* segment 1: aux1 - offset $0580, length $8000, loaded at $4000 (through $BFFF)
* segment 2: aux2 - offset $8580, length $1D00, loaded at $D000 (through $ECFF)
* segment 3: aux2 - offset $A280, length $0500, loaded at $FB00 (through $FFFF)
* segment 4: main - offset $A780, length $7F00, loaded at $4000 (through $BEFF)
  * main $BF00-$BFFF is ProDOS buffers
  * main $C000-$CFFF is I/O space
  * main $D000-$FFFF is ProDOS
* segment 5: _TBD_ - 38k so must be further subdivided. Disk Copy???

## Structure

### GUI Library "A2D"

AUX $4000-$8DFF is the GUI library used for the DeskTop application
and (presumably) for disk copy and Selector apps (TBD).

Entry point is $4000 with a ProDOS MLI-style calling convention

* Font is at $8800

### "DeskTop" Application

AUX $8E00-$FFFF (with hole at $C000-$CFFF for I/O and at $ED00-$FAFF for
data buffer) is the DeskTop application itself, with desktop and file
icons, menus, dialogs, and so on.