Resolution ][ Technical Notes
=============================

This document provides technical notes describing the Apple ][
double-high-resolution graphics mode and the methods used by Resolution ][
to manipulate graphics.

NOTE: This document is incomplete. More technical information will be
provided in future versions of Resolution ][.

DIRECTLY ACCESSING THE DOUBLE-HIGH-RESOLUTION MEMORY
----------------------------------------------------

Directly accessing the double-high-resolution graphics memory is
possible, although it is generally not recommended for drawing objects
onto the display. Use the Resolution ][ calls instead.

However, it may be desirable to access the double-high-resolution
graphics memory in order to copy an image from one memory location to
another, or to load or save an image into a file using the disk.

The Apple ][ double-high-resolution graphics memory spans 64 pages and
is located at memory locations Hex $2000-$3FFF (8192-16383) in main
memory and Hex $2000-$3FFF (8192-16383) in auxiliary memory.

Before accessing the double-high-resolution graphics memory, switch to
the double-high-resolution graphics mode by activating the following
soft switches (hardware registers):

	write a byte to  Hex $C00D	     for 80-column display
	write a byte to  Hex $C001	     for 80-column storage
	read a byte from Hex $C05E	     to disable AN3 and enable
					     double-high-resolution
	read a byte from Hex $C052	     for full-screen graphics
	read a byte from Hex $C057	     for high-resolution graphics
	read a byte from Hex $C050	     for viewing graphics

To access the main memory portion of the double-high-resolution display,
activate the following soft switch:

	write a byte to  Hex $C054

To access the main memory portion of the double-high-resolution display,
activate the following soft switch:

	write a byte to  Hex $C055
