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Apple II Plus in the Avalonia apps

Apple II Plus-specific features in the Avalonia Browser and Avalonia Desktop apps. The two runtimes share almost all of this; differences are called out inline.

For the emulated system's capabilities and current limitations, see the Apple II system overview.

ROMs

The Apple II Plus needs the system and character generator ROMs. The Disk II boot ROM is optional and enables disk booting. The configuration dialog can download them after a license acknowledgement. See Systems / Apple II / ROMs for accepted images and other details.

Upload the ROM binaries through the Apple II configuration dialog, or use the auto-download option. The browser stores loaded ROMs in local storage.

Point the app at a directory containing the ROM files, or use the auto-download option. The default directory is ~/Documents/Highbyte/DotNet6502/roms/Apple2 on macOS/Linux and the corresponding Documents directory on Windows.

Display

The default rasterizer renders 40-column text, lo-res graphics, hi-res graphics with NTSC artifact colors, and mixed graphics/text modes. The configuration dialog provides composite color, green, white, and amber monitor options. A lightweight text-only command-stream renderer is also available.

Input and audio

Host keyboard input supports US English and Swedish layouts, with automatic detection or an explicit setting. A host gamepad drives the Apple II game port. Optional keyboard-joystick controls use W/A/S/D, Space, and Left Shift.

The built-in speaker supports software-generated effects and sampled audio.

Gamepad input uses the browser Gamepad API, and speaker playback uses WebAudio.

Gamepad input uses SDL, and speaker playback uses OpenAL.

Memory and Disk II

The optional language card expands the machine from 48 KB to 64 KB and is enabled by default, allowing ProDOS 8 software to run. It can be disabled in the configuration dialog for a stock 48 KB Apple II Plus.

The read-only Disk II controller supports one drive with DOS 3.3- and ProDOS-ordered .dsk/.do images. The sidebar can insert, eject, and boot disks. See Systems / Apple II / Disk II for the supported workflow and limitations.

Apple II menu

The Apple II sidebar shared by both runtimes exposes:

  • Copy / Paste — copy Applesoft BASIC source to the clipboard or paste source into the running machine.
  • Download & Run programs — download and start a curated program; disk-booting titles require the Disk II ROM.
  • Disk drive — insert or eject a disk in drive 1 and boot it with PR#6.
  • Load / Save — load and save Applesoft BASIC files, load and start binaries, extract and run RAM-resident files from DOS 3.3 disk images, and load bundled examples.
  • Configuration — manage ROMs, the language card, monitor color, renderer, speaker audio, keyboard layout, keyboard joystick, and CPU compatibility.