TA11 Magnetic Tape Cassette controller

The TA11 Magnetic Tape Cassette controller is the UNIBUS controller for the TA11 Magnetic Tape Cassette System, which includes a controller and a TU60 Dual DECasette Transport, which uses Phillips-type tape cassettes holding a specially formulated tape.

The TA11 itself is a quad board, the M7892, which plugs into an SPC slot; a pair of BC08-S flat cables which connect the board and drive. All data transfer is via programmed I/O, one byte at a time.

Device registers

The TA11 has but two registers, a 'Control and Status' register and a 'Data Buffer' register.

Register	Abbreviation	Address
Control and Status Register	TACS	777500
Data Buffer Register	TADB	777502

777500: Control and Status Register (TACS)

Error	Block Check	Clear Leader	Write Lock	File Gap	Timing Error	Off Line	Unit Select	Transfer Request	Interrupt Enable	Ready	Last Byte	Function			Go
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

The functions are:

Code	Function	Abbreviation
0	Write File Gap	WFG
1	Write	WRITE
2	Read	READ
3	Space Reverse File	SRF
4	Space Reverse Block	SRB
5	Space Forward File	SFF
6	Space Forward Block	SFB
7	Rewind	REWIND

777502: Data Buffer Register (TADB)

Unused								Data
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00