a2stuff / intbasic

INTBASIC.SYSTEM for running Integer BASIC programs under ProDOS

INTBASIC.SYSTEM

This is a version of Steve Wozniak's Integer BASIC for the Apple II, with a wrapper that allows it to be loaded under ProDOS. It operates in two modes:

1. When invoked directly, the Integer BASIC > prompt is shown and you can type in and execute programs. The following additional commands are available at the prompt:

   • SAVE path saves the current program as an INT program file.
   • LOAD path loads an INT program file.
   • RUN path loads and runs an INT program file.
   • CHAIN path loads and runs an INT program file, without clearing variables.
   • PREFIX shows the current ProDOS prefix.
   • PREFIX path sets the current ProDOS prefix.
   • CAT or CATALOG shows the contents of the current directory.
   • CAT path or CATALOG path shows the contents of the specified directory.
   • DELETE path deletes the specified file.
   • RENAME path,newpath renames the specified file.
   • BSAVE path,A<address>,L<length> saves a BIN file.
   • BLOAD path[,A<address>] loads a BIN file.
   • BRUN path[,A<address>] runs a BIN file.
   • LOCK path and UNLOCK path lock/unlock the specified file.
   • STORE path and RESTORE path save/load variables to the specified IVR file.
   • -path runs INT, BIN or SYS files
   • BYE exits back to ProDOS.

2. When invoked as an "interpreter" for an INT file from a program selector (such as Bitsy Bye or Apple II DeskTop), the file is loaded and executed.

   • When the program ends normally or encounters an error, control is returned to ProDOS and the program selector.
   • Pressing Control+C will usually exit a program as well.
   • Optionally, hold down Open Apple or Solid Apple when starting to allow exiting the program to remain at the > prompt.

3. When invoked directly, if a INT file named HELLO is present, will be run automatically.

⚠️ Note that while Integer BASIC programs do have the ability to execute commands from BASIC with PRINT "<control-D>...", only the above commands are supported. Commands for operating on text files (OPEN, READ, etc) are not supported.

Integer BASIC

See Integer BASIC on Wikipedia or Apple II BASIC Programming Manual to learn more about the language.

This uses the Integer BASIC disassembly by Paul R. Santa-Maria from: https://6502disassembly.com/a2-rom/ (utilizing the SourceGen format conversion by Andy McFadden)

Modifications:

• Target address commented out (defined by includer)
• SYNTABLE-118 is corrected to SYNTABLE>>1
• Dead code is ifdef'd out

Notes:

• At runtime, the GR command is modified to ensure the hires screen is not shown.
• At runtime, CALL -10473 is intercepted to support the Programmer's Aid Music Subroutine.

Programmer's Aid

As a convenience, and since they were used by some Integer BASIC programs, the Programmer's Aid #1 Music Subroutine by Gary J. Shannon is included. This uses the annotated disassembly by James Davis from https://6502disassembly.com/a2-rom/PA1.html#A2PA1.6

Modifications:

• Target address commented out (defined by includer)
• Padding bytes commented out