ctu(4)ctu(4)Namectu - TU58 console interface
options MRSP (for VAX-11/750's with an MRSP prom)
Prior to Version 2.0, this device was referenced using
The interface provides access to the VAX-11/730 (11/725) and VAX-11/750
TU58 console cassette drive.
The interface supports only block I/O to the TU58 cassettes. The
devices are normally manipulated with the program, using the and
The device driver is automatically included when a system is configured
to run on a VAX-11/730 (11/725) or VAX-11/750.
The TU58 on a VAX-11/750 uses the Radial Serial Protocol (RSP) to com‐
municate with the CPU over a serial line. This protocol is inherently
unreliable as it has no flow control measures built in. On a
VAX-11/730 (11/725), the Modified Radial Serial Protocol is used. This
protocol incorporates flow control measures that ensure reliable data
transfer between the CPU and the device. Certain VAX-11/750s have been
modified to use the MRSP prom used in the VAX-11/730 (11/725). To
reliably use the console TU58 on an VAX-11/750 under ULTRIX, the MRSP
prom is required. For those VAX-11/750s without an MRSP prom, an unre‐
liable but often usable 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 a
VAX-11/730 (11/725) or use an MRSP prom. This unfortunately makes it
impossible to configure a single system that will properly handle TU58s
on both a VAX-11/750 and an VAX-11/730 (11/725) (unless both machines
have MRSP proms).
Frequent data overruns can occur if the VAX-11/750 TU58 is used while
in multiuser mode. The interface continues to function and errors are
handled, but transfer times may be lengthened considerably.
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 illegal state in the receiver finite state
machine. The state is shown along with the control byte of the received
tu%d: read stalled
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
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.
(only on a VAX-11/730 (11/725))