PARALLEL(HW) XENIX System V PARALLEL(HW)
Name
parallel - Parallel interface devices.
Description
There are several parallel devices:
/dev/lp0 Main parallel adapter.
/dev/lp1 Adapter on monochrome video card.
/dev/lp2 Alternate parallel adapter (on appropriate
machines).
It is not possible to have all three parallel devices on one
system. XT computers only allow the use of /dev/lp0. Some
AT computers allow the use of two parallel devices,
/dev/lp0, and either /dev/lp1, or /dev/lp2.
If a parallel device fails to interrupt properly, the
parallel driver enters ``poll mode.'' Once interrupts are
received from the device, the driver returns to its original
mode.
The parallel driver delays a certain amount of time when a
parallel device is closed. The amount of delay can affect
printer performance, but is necessary to compensate for
different sizes of printer buffers and printer speeds. For
example, this command sets the delay on close to 1 second,
specified in 10ths of a second by Ctrl-J (ASCII value 10):
stty eol "^J" < /dev/lp0
The default delay value is 2 seconds (^T).
Notes
Parallel adapters on add-on cards will function, but
switches must be set correctly. Some compatable computers
have ports lp0 and lp1 reversed.
The stty(C) command for output processing is supported on a
parallel device. stty options that have no effect on a
parallel device are ignored and no error messages are
displayed.
Usage
Usually invoked by through lp(C), but can be written to
directly.
Files
/dev/lp0
/dev/lp1
/dev/lp2
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PARALLEL(HW) XENIX System V PARALLEL(HW)
See Also
lp(C), lp(HW), lpadmin(C), lpinit(C), lpsched(C), serial(HW)
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