RK611 disk controller
The RK611 disk controller is the UNIBUS device controller for the RK06 and RK07 moving-head magnetic removable cartridge disk drives. All data transfers are done using DMA. Data is protected with a hardware-generated and checked error-correcting code (ECC); corrections (up to 11 bits) are done in software.
|M7904||Drive interface module|
At least three of the other slots are wired as UNIBUS SPC slots (and thus require G727 grant continuity cards to be inserted when no device is plugged into them); the status of the fourth is currently unknown. The slot on the end is necessarily a plain SPC slot; whether the others are MUD slots is likewise currently unknown.
One RK611 can control up to 8 drives; a flat cable plugs into a Berg connector on one of the cards, and runs to a transition adapter on the back of the rack. From there, a round cable runs to the first drive, and similar cables connect the rest of the drives, in series. A terminator must be plugged into the 'out' port of the last drive in the series.
The RK611 has no less than fifteen registers:
|Control and Status Register 1||RKCS1||777440|
|Word Count Register||RKWC||777442|
|Bus Address Register||RKBA||777444|
|Disk Address Register||RKDA||777446|
|Control and Status Register 2||RKCS2||777450|
|Drive Status Register||RKDS||777452|
|Attention Summary and Offset||RKAS||777456|
|Desired Cylinder Register||RKDC||777460|
|Data Buffer Register||RKDB||777464|
|Maintenance Register 1||RKMR1||777466|
|ECC Position Register||RKECPS||777470|
|ECC Pattern Register||RKECPT||777472|
|Maintenance Register 2||RKMR2||777474|
|Maintenance Register 3||RKMR3||777476|
The addresses given assume the standard base address (0777440); if this is changed, so will the addresses. Note also that there is no register at 777462.