RL11, RLV12 — RL01/RL02 disk controller

The RL11 is DEC’s controller for the RL01 and RL02 cartridge disks: up to four drives on one controller, each holding a removable pack of 5 MB (RL01) or 10 MB (RL02). QUniLator emulates the controller and its four drives. The controller is listed as rl, the drives as rl0 to rl3, and each drive’s pack is an image file on the board.

UNIBUS · UniBone

The controller is an RL11: base address 774400, vector 160, bus request level 5, backplane slot 15. It moves data to and from 18-bit addresses, with the top two address bits in the control and status register.

QBUS · QBone

The controller is an RLV12: base address 17774400 (174400 as a program names it), vector 160, bus request level 4, backplane slot 15. It carries a fifth register, the bus address extension, which gives it the full 22-bit address range.

Boot XXDP from an emulated RL02 builds a machine around it on a real PDP-11/53, step by step.

What the machine sees

Registers	CS, BA, DA and MP at the base address and the three words above it; on the RLV12 also BAE, the fifth word
Drives	Four drive slots, units 0 to 3. Each enabled drive is an RL01 (256 cylinders, 5,242,880 bytes) or an RL02 (512 cylinders, 10,485,760 bytes), set by its type
Disk format	2 heads, 40 sectors of 256 bytes a track. Read Header returns the sector headers a real pack carries, with their CRC
Drive status	The drive state, heads, cover, drive type, volume check and write lock, in the Get Status word a real drive returns
Timing	A seek takes the time a real positioner does, 5 ms for one track to 100 ms across the pack, and every seek ends with the 6.5 ms settle before the drive is ready
Empty slot	A drive slot with no enabled drive answers with neither Drive Ready nor Drive Error, and a function addressed to it ends in Operation Incomplete. That is how a program finds out which drives the machine has

A seek given to a drive that is still settling from the previous one waits for it, and a read or write waits for the selected drive to come ready, both up to the controller’s own operation-incomplete timeout. A program that overlaps seeks with other work sees the drive where it sent it.

Using it

1. Add rl on the Configurations screen, with a drive — rl0 — whose image names a pack. The board ships the XXDP 2.5 pack as dl/xxdp25.rl02.dsk.
2. Enabling a drive switches it on, and a drive holding an image spins up by itself and comes READY. The drive’s four lamps are among its status parameters.
3. An image can be changed while the pack spins: the drive spins the old one down, takes the new one and spins it up.

A drive is an RL02 unless its type is set to RL01.

A blank pack has no factory bad-sector file on its last track, which DEC’s drive diagnostics look for. Before running them on a scratch pack, copy the last cylinder from a pack that has one. Run the diagnostics that write on a drive other than the one the system booted from.

The RLV12’s maintenance mode is outside the model.

What has been verified

• On a QBone in a PDP-11/53, the RLV12 and an RL02 pass DEC’s XXDP diagnostics ZRLG and ZRLH (controller), and ZRLI, ZRLJ and ZRLN (drive), to the end of pass with no errors. The few tests that time the drive against a clock skip themselves when the supervisor has no clock to use. The random exerciser ZRLK runs for many minutes with no error. The drive tests were run on drive 1, with a scratch pack carrying a copied factory bad-sector file.
• The PDP-11/53’s own boot ROM boots XXDP from an emulated RL02, as the walkthrough shows.
• On a UniBone, the emulated PDP-11/20 boots XXDP from an emulated RL02 through the RL11, with the M9312’s DL boot ROM.

Controller parameters

It has no parameters of its own.

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

RLV12

It has no parameters of its own.

It also carries the parameters under controller parameters.

RLV11

The RLV11 is the 18-bit QBUS controller: the RL11’s registers at bus request level 4. Neither board offers it.

It has no parameters of its own.

It also carries the parameters under controller parameters.

Drive parameters

Settings

What a configuration stores and an operator sets.

Parameter	Short	Value	Default	What it is
powerswitch	pwr	0 or 1	0	State of POWER switch
runstopbutton	rb	0 or 1	0	State of RUN/STOP button
writeprotectbutton	wpb	0 or 1	0	Writeprotect button pressed
coveropen	co	0 or 1	0	1, if RL cover is open
spinupdelay	sud	0 or 1	0	1 = model the drive’s spin-up/spin-down delay; 0 = ready at once

Status

What the device reports as it runs. A configuration does not store these.

Parameter	Short	Value	What it is
rotation	rot	number, rpm	Current speed of disk
state	st	number	Internal state
loadlamp	ll	0 or 1	State of LOAD lamp
readylamp	rl	0 or 1	State of READY lamp
faultlamp	fl	0 or 1	State of FAULT lamp
writeprotectlamp	wpl	0 or 1	State of WRITE PROTECT lamp

It also carries the parameters under parameters every drive has.

In detail

rotation, state

What the drive is doing. rotation is the spindle speed: 2400 rpm with a pack spinning, 0 at rest. state is the drive state the RL01/RL02 reports to the controller’s Get Status, as DEC’s manuals number it: 0 load cartridge, 1 spin up, 2 brush cycle, 3 load heads, 4 seek, 5 lock on, 6 unload heads, 7 spin down. A drive that is powered off shows 255.

A seek to another cylinder holds the drive in state 4 for the time a real positioner takes, from 5 ms for one track to 100 ms across the whole pack; a seek to the cylinder the heads are on stays in state 5. Either way the drive drops READY for the 6.5 ms the positioner takes to settle before it accepts the next command.

powerswitch, runstopbutton, loadlamp, readylamp, faultlamp, writeprotectlamp, writeprotectbutton

The drive’s front panel. powerswitch is the POWER switch: enabling the drive closes it and disabling it opens it, so it needs no attention in normal use. A drive switched off is not ready and its panel is dark.

runstopbutton is the LOAD button. Pressed (1), a drive holding a cartridge spins up, loads its heads and comes READY; released (0), it unloads its heads and spins down to LOAD. Setting image on a drive at rest presses it, and a new image on a spinning drive releases it and presses it again once the pack is at rest, so a drive with a medium comes READY without it being touched.

The four lamps follow the drive’s state as DEC’s RL01/RL02 manuals give them: LOAD with the spindle stopped, READY with the heads on a track and settled, FAULT on a drive fault or a write the drive refused, and WRITE PROT while the pack is write-protected.

writeprotectbutton is the WRITE PROT switch. Pressed, the drive refuses every write with a write gate error. An image the board can only read is write-protected the same way, whatever the switch says.

coveropen

The cartridge cover. It can be opened (1) only while the drive is in LOAD, and a drive with its cover open does not spin up. The drive reports the cover in its status word, and DEC’s drive diagnostic ZRLI has it opened during its tests.

spinupdelay

With 1, a drive takes the time a real one does to start and stop: 25 seconds of spin-up before the heads load and READY lights, and as long again to spin down to LOAD. With 0, it is READY as soon as it is loaded and at LOAD as soon as it is stopped, which saves those waits on every boot and every cartridge change. Seek and settle times are modelled either way.