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ROM 4X and 5X

ROM 4X and 5X are enhanced firmwares for the Apple //c and Apple IIc Plus.

Main features:

  • Initializes memory expansion card without erasing it if it already contains a boot sector. This is intended for battery-backed memory expansions made by A2Heaven.
    • Allows dropping into the monitor immediately.
    • Allows clearing memory expansion card.
    • Allows launching diagnostics.
    • Allows selecting boot device.
      • 4X: Allows booting external 5.25 drive if disk supports it.
  • 4X: With battery-backed RAMdisk, can configure default boot option.
  • 5X: Replaces accelerator firmware.
    • CTRL+ESC+RESET toggles accelerator speed and persists across ordinary resets.
    • CTRL+TAB+RESET brings up a menu that lets you set accelerator state and some option.

In development:

  • 5X - default boot option configuration like 4X, enhanced to set default accelerator state as well.

See ROM 4X and 5X on GitHub.



In addition to the source code, GitHub releases starting October 2017 will have a “binary” release attached that includes binary patches and a patching script to apply them to a source ROM.