EXOS 2.1 Cassette Driver Specification

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7. Quick Reference Summary

7.1 EXOS Calls

Open Channel

Opens a read channel and gets the header chunk.

Only one read channel allowed.

Device name "TAPE:", unit number ignored.

Filename compared with file on tape (unless null).

No EXOS variables need to be set up before open.

Create Channel

Opens a write channel and write the header chunk.

Only one write channel allowed.

Device name "TAPE:", unit number ignored.

Filename written into header.

EXOS variables LV_TAPE, SP_TAPE and PROTECT must be set up before create.

Close/Destroy Channel

Treated identically.

For a write channel will write out any buffered data.

Read Character/Block

Only allowed for read channel.

Read characters from buffer until empty, then read another data chunk from tape.

Write Character/Block

Only allowed for write channel.

Writes characters into buffer and writes it out to tape when it gets full.

Read Status

Returns C=0FFh at end of file or after an error

Returns C=000h otherwise.

Set Status

Not supported.

Special Function

No special functions.

7.2 EXOS Variables

These must be set up before a channel is created:

LV_TAPE - Tape output level (1..6)

SP_TAPE - Tape output speed (0=fast, 0FFh=slow)

PROTECT - Non­zero to write out protected file

Miscelaneous:

TAPE_SND - nonzero to suppress tape sound feedthrough

REM1/REM2 - Control tape remote relays 0=on, 0FFh for off.