RK11, RKV11 — RK05 disk controller

The RK11 is DEC’s controller for the RK05 cartridge disk, the 2.5 MB removable pack of the early PDP-11 systems: up to eight drives on one controller. QUniLator emulates the controller and its eight drives. The controller is listed as rk, the drives as rk0 to rk7, and each drive’s pack is an image file on the board.

UNIBUS · UniBone

The controller is an RK11: base address 777400, vector 220, bus request level 5, backplane slot 10. The two memory extension bits in RKCS carry a transfer to 18-bit addresses.

QBUS · QBone

The controller is an RKV11: base address 17777400 (177400 as a program names it), vector 220, bus request level 4, backplane slot 13. It addresses memory with the 16 bits of RKBA, so its transfers reach the first 64 KB; the memory extension bits in RKCS read and write but do not move the transfer.

What the machine sees

Registers	RKDS, RKER, RKCS, RKWC, RKBA, RKDA at the base address and the five words above it, RKDB at base + 16
Drives	Eight drive slots, units 0 to 7. Each is an RK05: 203 cylinders, 2 surfaces, 12 sectors of 512 bytes a track, 2,494,464 bytes
Functions	Control Reset, Write, Read, Write Check, Seek, Read Check, Drive Reset and Write Lock, with the format bit on Read and Write
Seek	A Seek or Drive Reset ends with a search-complete interrupt when interrupts are enabled, and the drive’s sector counter turns while it is idle
Timing	A seek takes from 3 ms for a short move to about 27 ms across the whole pack, and each sector read or written takes 10 ms

A drive is ready once its image is open: setting the image is loading the pack, and there is no front panel to work. A function given to a drive that is not enabled ends with Nonexistent Drive, and one given to a drive that is enabled but not ready with Drive Error. Write Lock locks the selected drive: RKDS shows it write-protected, and a Write to it ends with Write Lockout Violation before anything is written. Drive Reset and bus INIT release the lock.

Using it

1. Add rk on the Configurations screen, with a drive — rk0 — whose image names a pack.
2. Enable the controller and the drive. The drive is ready for the machine as soon as the image is open.

An RK05 image is the pack’s sectors in order, cylinder by cylinder, surface 0 before surface 1: the layout SimH and other emulators use.

What has been verified

No DEC diagnostic run on this controller is recorded in the project yet.

Controller parameters

It has no parameters of its own.

It also carries the parameters under parameters every card on the bus has.

RKV11

It has no parameters of its own.

It also carries the parameters under controller parameters.

Drive parameters

It has no parameters of its own.

It also carries the parameters under parameters every drive has.