7.15 SYS_ISTTY (0x09)

Checks whether a file is connected to an interactive device.


On entry, R1 contains a pointer to a one-word argument block:

word 1

A handle for a previously opened file object.


On exit, R0 contains:

  • 1 if the handle identifies an interactive device

  • 0 if the handle identifies a file

  • a value other than 1 or 0 if an error occurs.

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