NAME

tu — VAX-11/750 TU-58 console cassette interface

DESCRIPTION

The tu interface provides access to the VAX-11/750 TU-58 console cassette drive.

The interface supports only block I/O to the TU-58 cassettes. The devices are normally manipulated with the dd(1) program.

The device driver is automatically included when a system is configured to run on an 11/750.

The TU-58 on an 11/750 uses the Radial Serial Protocol (RSP) to communicate with the cpu over a serial line. This protocol is inherently unreliable as it has no flow control measures built in.

FILES

/dev/tu0

DIAGNOSTICS

tu%d: lost recv interrupt.

A timer watching the controller detected no interrupt for an extended period while an operation was outstanding. This usually indicates that one or more receiver interrupts were lost and the transfer is restarted.

HISTORY

The tu driver appeared in 4.1BSD. A new driver showed up in NetBSD 1.2.

BUGS

The VAX-11/750 console interface is unusable while the system is multi-user, because interrupts occur at a very high priority level (spl7) and cannot be blocked with splbio. Use this driver only when the system is running single-user and, even then, with caution.