TU(4) BSD/vax Kernel Interfaces Manual TU(4)NAMEtu — VAX-11/730 and VAX-11/750 TU58 console cassette interface
(for VAX-11/750's with an MRSP prom)
The tu interface provides access to the VAX 11/730 and 11/750 TU58 con‐
sole cassette drive(s).
The interface supports only block I/O to the TU58 cassettes. The devices
are normally manipulated with the arff(8) program using the ``f'' and
The device driver is automatically included when a system is configured
to run on an 11/730 or 11/750.
The TU58 on an 11/750 uses the Radial Serial Protocol (RSP) to communi‐
cate with the cpu over a serial line. This protocol is inherently unre‐
liable as it has no flow control measures built in. On an 11/730 the
Modified Radial Serial Protocol is used. This protocol incorporates flow
control measures which insure reliable data transfer between the cpu and
the device. Certain 11/750's have been modified to use the MRSP prom
used in the 11/730. To reliably use the console TU58 on an 11/750 under
UNIX, the MRSP prom is required. For those 11/750's without an MRSP
prom, an unreliable but often useable interface has been developed. This
interface uses an assembly language ``pseudo-dma'' routine to minimize
the receiver interrupt service latency. To include this code in the sys‐
tem, the configuration must not specify the system will run on an 11/730
or use an MRSP prom. This unfortunately makes it impossible to configure
a single system which will properly handle TU58's on both an 11/750 and
an 11/730 (unless both machines have MRSP proms).
/dev/tu1 (only on a VAX-11/730)
tu%d: no bp, active %d. A transmission complete interrupt was received
with no outstanding I/O request. This indicates a hardware problem.
tu%d protocol error, state=%s, op=%x, cnt=%d, block=%d. The driver
entered an illegal state. The information printed indicates the illegal
state, operation currently being executed, the I/O count, and the block
number on the cassette.
tu%d receive state error, state=%s, byte=%x. The driver entered an ille‐
gal state in the receiver finite state machine. The state is shown along
with the control byte of the received packet.
tu%d: read stalled. A timer watching the controller detected no inter‐
rupt 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 (11/750 only).
tu%d: hard error bn%d, pk_mod %o. The device returned a status code
indicating a hard error. The actual error code is shown in octal. No
retries are attempted by the driver.
The tu driver appeared in 4.1BSD.
The VAX-11/750 console interface without MRSP prom is unuseable while the
system is multi-user; it should be used only with the system running sin‐
gle-user and, even then, with caution.
4th Berkeley Distribution June 5, 1993 4th Berkeley Distribution