RL11 disk controller

The RL11 disk controllers (the original RL11 for the UNIBUS, and the RLV11 and RLV12 for the QBUS) were for the RL01 and RL02 disk drives.

RLV12

The RL11 was a hex board, the M7762. The RLV11 consisted of two quad boards, the M8013 and M8014, which used the CD interconnect to communicate; it was program compatible with the RL11. The RLV12 was a single quad board, the M8061; it was mostly program compatible, but added a 'Bus Address Extension' register for use on Q22 systems.

All have a 40-pin Berg connector holding a flat cable, which runs to a bulkhead-mounted converter from the flat cable to a special inter-drive cable (round in cross-section, with special locking connectors). (If the flat cable is plugged in the wrong way around, nothing is damaged; the drive merely turns on its 'fault' light.)

The cable runs from the converter to the first drive; up to 4 drives can be connected to a single controller, using a bus running from one drive to the next, with a terminator in the last drive of the string.

Controller capabilities

The controller and drive combination can execute 8 different commands:

• No Operation
• Write Check
• Get Status
• Seek
• Read Header
• Write Data
• Read Data
• Read Data Without Header Check

Spiral reads and writes (i.e. multi-block reads which start on one track, and overflow to the next) are not supported; multiple separate read/write commands are needed, with a seek to the next track between each pair.

Device registers

The RL11 controller includes 4 (5 for the RLV12) read-write registers:

Register	Abbreviation	Address
Control Status Register	RLCS	774400
Bus Address Register	RLBA	774402
Disk Address Register	RLDA	774404
Multipurpose Register	RLMP	774406
Bus Address Extension Register RLV12 only	RLBAE	774410

774400: Control Status Register (RLCS)

CERR	DE	NXM	DLT/HNF	DCRC/ HCRC	OPI	DRVSEL		CRDY	IE	ADDR EX		FUNC			DRDY
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

774402: Bus Address Register (RLBA)

BA15 <---> BA01															0
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

774404: Disk Address Register (RLDA)

During a 'Seek' command on an RL01:

0	CYL ADDR DIFF								Reserved		HD SEL	0	DIR	0	1
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

During a 'Seek' command on an RL02:

CYL ADDR DIFF									Reserved		HD SEL	0	DIR	0	1
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

During a 'Read Data' or 'Write Data' command on an RL01:

0	CYL ADDR								HD SEL	SECTOR
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

During a 'Read Data' or 'Write Data' command on an RL02:

CYL ADDR									HD SEL	SECTOR
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

During a 'Get Status' command:

Unused								MBZ				RESET	0	GT STA	1
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

774406: Multipurpose Register (RLMP)

During a 'Get Status' command:

WDE	CHE	WL	SKTO	SPE	WGE	VC	DSE	Rsvd	HS	CO	HO	BH	STATE
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

State Code	State
0	Load Cartridge
1	Spin Up
2	Brush Cycle
3	Load Heads
4	Seek
5	Lock On
6	Unload Heads
7	Spin Down

During a 'Read Header' command, three successive reads to the Multipurpose Register will return, on an RL01:

0	CYL ADDR								HD SEL	SECTOR
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

and on an RL02:

CYL ADDR									HD SEL	SECTOR
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

in the first word, all 0's in the second word, and the header CRC in the third.

During a 'Read Data' or 'Write Data' command:

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

774410: Bus Address Extension Register (RLBAE)

Unused										BA21 <---> BA16
15	14	13	12	11	10	09	08	07	06	05	04	03	02	01	00

Note: This register is present in the RLV12 only.