How do the function keys affect start-up?

The Atari Operating System checks the status of certain function keys during start-up, and alters the standard start-up procedure accordingly. In order for one or more function keys to be taken into account, it is sufficient to press it or them for about 5 seconds during start-up:

  • The "START" key instructs the computer to load a machine language program from cassette tape
  • The "OPTION" key commands the computer to disable the internal Atari BASIC in computers equipped with it, i.e. all computers except the 400, 800 and 1200XL
  • The "HELP" key commands the 1200XL to start the "Self-Test" program
  • The "SELECT" key commands the XEgs whose external keyboard is connected to launch the internal "Missile Command" game. Many other scenarios exist with the XEgs and are described in full details in the FAQ (section: "What is the Atari XE game system?")
Run the cartridge-based OSS BASIC XE language with the diskette-based "BASIC XE extension disk"

Typical use case: I want to take advantage of additional features, such as detailed error messages with text, or functions that are only available on the diskette, such as FAST, PROCEDURE, RENUM, etc.

Assuming that the whole system is powered off and all required cables properly connected:

  1. Turn on the TV or monitor.
  2. Insert your floppy disk drive #1 in the SIO chain and power it on. Insert the "BASIC XE extension disk" diskette in this floppy disk drive #1.
  3. [Specific] On a 400, open the cartridge door (lid), remove any previously inserted cartridge. Insert the OSS BASIC XE cartridge. Close the cartridge door (lid).
  4. [Specific] On a 800, open the cartridge door (lid), remove any previously inserted cartridge in both Left & Right slots. Insert the OSS BASIC XE cartridge in the Left slot. Close the cartridge door (lid).
  5. [Specific] On a 1200XL, 600XL/800XL, 65XE/130XE/800XE & XEgs, remove any previously inserted cartridge. Insert the OSS BASIC XE cartridge.
  6. [Specific] On a XEgs, plug the external keyboard.
  7. Turn on the computer.
Using a communication program on cartridge with the Atari 830 Modem plugged into the Atari 850 interface

Typical use case: I want to run a communication program on cartridge, that might use a diskette to store data, and that will use the Atari 830 Acoustic modem plugged on the Atari 850 interface to communicate with the outside world.

Note: The Atari 830 acoustic modem needs an R: driver/handler. This driver/handler is usually loaded into the computer in one of two classic ways (there are other alternatives):

  1. If no floppy disk drive #1 is turned on when the computer boots up, the Atari 850 interface will respond to the computer polling the SIO bus, asking if a drive #1 is present. The Atari 850 interface will then "pretend" to be this floppy disk drive #1 to provide the computer with the R: driver/handler to load.
  2. If a floppy disk drive #1 is turned on with a classic Atari DOS diskette (DOS 2, DOS 2.5, DOS 3, DOS XE, etc) when the computer boots up, then the driver/handler will be loaded from diskette. These versions of DOS contain an R: driver/handler which will be loaded automatically.

Assuming that the whole system is powered off and all required cables properly connected:

  1. Turn on the TV or monitor.
  2. Turn on the Atari 850 interface.
  3. Turn on the Atari 830 Acoustic modem that is plugged on the Atari 850 interface.
  4. Turn on floppy disk drive #1 and insert a bootable DOS diskette that features a R: driver/handler.
  5. [Specific] On a 400, open the cartridge door (lid), remove any previously inserted cartridge. Insert yours. Close the cartridge door (lid).
  6. [Specific] On a 800, open the cartridge door (lid), remove any previously inserted cartridge in both Left & Right slots. Insert yours in the Left slot (unless explicitly designed for Right slot; only a handful of cartridges are). Close the cartridge door (lid).
  7. [Specific] On a 1200XL, 600XL/800XL, 65XE/130XE/800XE & XEgs, remove any previously inserted cartridge. Insert yours.
  8. [Specific] On a XEgs, plug the external keyboard.
  9. Turn on the computer.
Using a Word Processing program on cartridge with the Atari 825 printer plugged into the Atari 850 interface

Typical use case: I want to run a Word Processing program on cartridge, that might use a diskette to store data, and that will use the Atari 825 80-Column Dot matrix impact printer plugged on the Atari 850 interface.

Note: If you intend to use just the Atari 825 80-Column Dot matrix impact printer and no other devices connected to the Atari 850 interface, then you do not need the R: driver/handler. This R: driver/handler is required for Serial devices (typically, a modem) and not for Parallel devices (typically, a printer).

Assuming that the whole system is powered off and all required cables properly connected:

  1. Turn on the TV or monitor.
  2. Turn on the Atari 850 interface.
  3. Turn on the Atari 825 80-Column Dot matrix impact printer that is plugged on the Atari 850 interface.
  4. Turn on floppy disk drive #1 and insert a bootable DOS diskette.
  5. [Specific] On a 400, open the cartridge door (lid), remove any previously inserted cartridge. Insert yours. Close the cartridge door (lid).
  6. [Specific] On a 800, open the cartridge door (lid), remove any previously inserted cartridge in both Left & Right slots. Insert yours in the Left slot (unless explicitly designed for Right slot; only a handful of cartridges are). Close the cartridge door (lid).
  7. [Specific] On a 1200XL, 600XL/800XL, 65XE/130XE/800XE & XEgs, remove any previously inserted cartridge. Insert yours.
  8. [Specific] On a XEgs, plug the external keyboard.
  9. Turn on the computer.

Knowledge base article: kb-howto-0003-atari-8bit-how-to-run-a-program-on-tape-disk-cartridge-advanced-scenarios.
REV. 009.

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