Latest release of ProDOS is 2.4.2

ProDOS 2.5 alpha 8 pre-release is available

Bitsy Bye


  • A new program launcher with many features.
  • Runs on all Apple II computers and CPUs: 6502, 65c02 or 65816.
  • Allows drives to be selected directly by slot using number keys 1-7.
  • Allows files to be selected by typing the first letter of their filename.
  • Displays and quickly scrolls through up to 2,733 files per directory.
  • Displays and allows selection of all files on a drive, not just System files and directories like previous launchers.
  • Displays file types and allows launching Applesoft Basic, Binary, Text exec, and GS/OS S16 files via Basic.System.
  • Displays the slot and drive of each device.
  • Does not abort on drive errors, but instead lists and allows launching of all readable files.
  • The code and data size for Bitsy Bye is less than 1KB, with room to spare thanks to Peter Ferrie (qkumba).
  • Bitsy Bye is only $300 bytes long yet hides an Easter egg.
    Look for it in QUIT.SYSTEM on the ProDOS 2.4, and later, disks.

How the system launches Bitsy Bye (QUIT.SYSTEM) on boot

  • ProDOS will always launch the first program with a suffix of .SYSTEM and a file type of SYS
  • The order is determined by the placement in the disk catalog, not by the spelling.
  • To launch QUIT.SYSTEM when ProDOS starts up, it must be the first .SYSTEM file in the catalog.
  1. Format a blank ProDOS disk (also include the boot sector / loader )
  2. Files need to be in this order in the catalog …
    • 2.1. copy PRODOS
    • 2.2. copy BITSY.BOOT
    • 2.3. copy QUIT.SYSTEM
    • 2.4. copy BASIC.SYSTEM
  • BITSY.BOOT should be the first SYS file.

When Booting:

  1. The boot sector searches the volume for and loads PRODOS
  2. PRODOS searches for the first SYS file, which is BITSY.BOOT.
  3. BITSY.BOOT will then launch the next .SYSTEM file on the disk.
    If you want BASIC.SYSTEM to be the first SYS file in the disk catalog, copy it before QUIT.SYSTEM.
    To make the system launch Bitsy Bye on boot, copy QUIT.SYSTEM BEFORE BASIC.SYSTEM.

The benefit of using QUIT.SYSTEM vs. Something like ProSel

  • It allows you to also have BASIC.SYSTEM in the root dir.
  • Bitsy Bye needs BASIC.SYSTEM if you want to use Bitsy to run BAS, BIN, or TXT (exec) files.

Can Bitsy-Bye operate in 80-column mode?

  • Bitsy-Bye is a super lean piece of assembly code.
  • Line 1 of the code for Bitsy-Bye enables 40-column mode,
    followed by line 2 which disables 80-column mode.

  • A feature request for a version of Bitsy-Bye with 80-column mode support has been submitted, however there is no 80-column support version of Bitsy-Bye available at this time.