RL11 disk controller

From Computer History Wiki
(Redirected from RLV12)
Jump to: navigation, search

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.