Technical data

1.3 Functional Description

The drive is designed to stream in a start/stop environment using standard start/stop

software. It uses an internal one-megabyte cache memory as an electronic tape buffer that

decouples the physical and logical tape operations. The primary function of the cache memory

is to provide higher performance on systems that are not able to stream.

The drive has three main functional assemblies: the interface, the electronics, and the servo

mechanism. These assemblies interact to accomplish the various functions performed by the

drive.

1.3.1 Interface

The SCSI 2 interface translates bus commands into tape-drive-executable commands. The

interface also translates tape drive data and status signals into the correct bus format.

1.3.2 Electronics

A Z8002 microprocessor controls all necessary logic functions relating to read/write, servo

control, cache memory, and the transfer of data and commands in the drive. An 80188

microprocessor operates in synchronous with the Z8002 control communications with the

external SCSI bus.

The SCSI bus transmits data to the TSZ07, which writes it on the tape with the PE and

GCR recording methods at 1600 and 6250 bpi. Nine tracks (8 data, 1 parity) are written

simultaneously across the width of the tape.

The TSZ07 reads recorded data from the tape and transfers it to the SCSI bus. To perform

this function, a microprocessor interprets commands from the interface; accelerates and

decelerates the tape; positions it at the read/write head; controls formatting; and provides

status to the host.

The TSZ07 is self-loading. The user inserts a reel of tape into the front panel opening, and

presses the LOAD switch. Then, the drive automatically threads the tape around the tension

sensor, across the read/write head, and around the take-up hub. Finally, the drive tensions

the tape, and positions the tape at the Beginning of Tape (BOT) .

The drive has automatic error recovery capability. Errors detected during a write operation

result in the tape being automatically backspaced, erased, and the data rewritten on a fault-

free section of tape. The drive corrects read errors "on the ﬂy" for up to two tracks in GCR

and one track in PE. The drive automatically backspaces and retries multi-track read errors

that are not correctable.

Standard features of the drive electronics include:

• Conﬁguration parameters stored in non-volatile memory

• One megabyte of cache memory

• Custom analog read ampliﬁer chip for each track

• Extensive use of large scale integration (LSI) and surface mount technology

• Solid-state tension transducer

1–10 Introduction