a2fc.system

a very small .a2fc graphics file viewer for Apple II computers

.a2fc ("Apple II Full Color") files are uncompressed double hi-res graphics files that can be displayed on any Apple //e or later with an extended 80-column card.

Usage

a2fc.system has no user interface. It is designed to take the pathname of an .a2fc file as a startup program, as explained in ProDOS 8 Technical Reference Manual §5.1.5.1. If this pathname is not supplied, a2fc.system will simply quit.

ProDOS 2.4.1 users: if you rename a2fc.system to basis.system and put it in the root directory of your startup disk, you can select any .a2fc file in Bitsy Bye and it will be passed to basis.system as the startup program and displayed properly.

ProSel users: you can create a ProSel item that displays an .a2fc graphic file. Assuming a2fc.system is /HD/BIN/A2FC.SYSTEM and your graphic file is /HD/PHOTOS/MYPIC.A2FC:

Screen title:     -your choice-
Prefix:           ?BIN/
Application path: A2FC.SYSTEM
Startup:          ?PHOTOS/MYPIC.A2FC

Memory Usage

a2fc.system loads at $2000 (like any .system file) but relocates itself to zero page. It loads the given .a2fc file into hi-res page 1, but only $2000 bytes at a time, so it never touches hi-res page 2.

0050..0096     relocated program code
2000..3FFF     graphic data
2000..3FFF/aux graphic data
9200..95FF     ProDOS file buffer

Tools to create A2FC files

• BMPA2FC (Windows)
• Buckshot (macOS)

Beagle Graphics used separate files to store double hi-res graphics, a .bin and .aux file. You can easily combine these into a single .a2fc file. The .aux part goes first.

]BLOAD MYPIC.AUX,A$2000
]BLOAD MYPIC.BIN,A$4000
]BSAVE MYPIC.A2FC,A$2000,L$4000