A8CAS - software for reading/writing Atari 8-bit cassettes

Support for Turbo systems

A8CAS contains preliminary support for tape turbo systems.

There exist several Turbo systems for Atari cassette recorders, mostly originating from Central Europe. A turbo system speeds up communication between an Atari computer and its recorder, allowing programs to load faster and to take less space on tape.

A turbo system typically consists of a piece of electronic circuitry that has to be installed inside an Atari tape recorder, and some software to support the hardware (typically on a cartridge). The circuitry allows to read and write data on a tape in a different way, incorporating Pulse Width Modulation, as opposed to the standard mechanism of Frequency Shift Keying. The circuitry can be switched on and off; depending on the turbo system, it is done either manually by a switch on the recorder's case, or automatically by the turbo software.

Most turbo systems are similar in that they use Pulse Width Modulation to encode/decode data, but they differ in:

Supported turbo systems

Support for turbo systems in A8CAS is currently limited to reading tapes from sound files; saving and conversion to CAS is not supported.

The Atari800 patch allows to select a turbo system of choice; several options are available:

Something to try

Typical view during loading of AST tapes
Typical view during loading of AST tapes

Here is a ROM image of a utility cartridge for AST, and a tape image of a program in the AST format. Try loading it in the patched Atari800:

  1. Run the emulator.
  2. Turn SIO patch off, and set Tape Management→Turbo type to AST (XC12).
  3. Load the cartridge image to the emulator; when asked to choose the cartridge type, select Phoenix.
  4. Reset the emulator with BASIC turned off (hold OPTION when resetting). The cartridge will start.
  5. In the cartridge's menu press 1. The AST loader will be loaded.
  6. Now load the AST tape image to Atari800.
  7. Press Space and loading will start. When the name of the program being loaded appears, press Space again.

Check out other AST images as well.