DISK  DRIVES   and   CONTROLLERS

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In this  disk  folder are descriptions of all the disk drives and their controllers that I have in my collection :

• RM03
  The RM03 is a hard disk drive and has its own small free-standing cabinet on wheels.
  Data is stored on a removable pack called RM03P which has 5 platters. The RM03 has a MASSBUS interface.

• RM80
  The RM80 is a hard disk drive in which the platters are fixed. It is basically the RA80, but the RM80 is just like the RM03: the drive has its own small cabinet and also incorporates the MASSBUS interface.

• RA60 / RA81
  The RA60 is a hard disk drive of which the platters (pack) can be removed and the RA81 is a hard disk drive in which the platters are fixed. Both drives use the same interface called SDI (Standard Disk Interconnect). The interface hardware described here are the SDI interface for QBUS (QDA50 - M7164 and M7165) and the SDI interface for UNIBUS systems (UDA50 - M7161 and M7162).

• RK05 / RK05f
  The RK05 disk drive is in my humble opinion a drive in its own league. The RK05 is a removable hard disk drive, and the cartridge contains one platter.
  The RK05f is basically an RK05, but the cartridge is fixed mounted and can not (easily) be swapped. Since the positioning of the cartridge is better in the fixed version the data capacity is doubled.
  The controller for the RK05(f) is a dedicated backplane with 4 modules, called RK11 and is UNIBUS based. The RK11 can control up to 8 drives, but the RK05f appears as two logical drives with an even and an odd number, for example 2/3.
  A controller for RK05's for QBUS-based system exists, but I have not seen one yet.

• RK06 / RK07
  The RK06 and RK07 disk drives are very similar to the RL01/RL02 removable pack disk drives. The RK06 and RK07 are removable hard disk drive, and the cartridge contains two platters.
  Just as with the RL01/RL02 drives, the latter one (RK07) doubles the data storage capacity of a cartridge compared to the RK06. The controller for the RK06 and RK06 is a dedicated backplane with several modules, called RK611 and is UNIBUS based.
  The RK611 can control up to 8 drives.
  

• RL01 / RL02
  The RL01 and RL02 disk drives are the "work horses" for the old PDP-11's. They combine a fair amount of storage with easy handling and high reliability. These drives use a cartridge designed for the drive, so there is a cartridge (with a grey RL01K-DC label) for the RL01 drive, and a cartrdige of exactly the same dimensions (with a blue RL02K-DC label) for the RL02 drive. The data capacity of the RL01 cartridge is 5 Mb, the RL02 doubles that.
  The interface/controller is identical for both drives and you can connect up to 4 drives to a single controller. The controller for the UNIBUS is a single hex board called RL11 and the type number is M7762. The controller for the QBUS exists in two variations. The older model consists of two quad boards and is called RLV11, the type numbers are M8013 and M8014. The newer model is a single quad board and is called RLV12, the type number is M8061.

• RX01 / RX02
  The RX01 disk drive actually contains two 8 inch floppy disk drives. The two floppy drives are single density only, and this drive has its own controller. For UNIBUS it is the RX11, type number M7846, and for the QBUS it is the RXV11, type number M7946.
  The RX02 disk drive looks almost the same as the RX01 drive. The data format on the floppy disk is a little strange as all the fields in a sector and track are in single density whereas the data field in each sector is double density. That is why the RX02 floppy is called "double density". To handle the high data transfer that comes with double density, the interface uses DMA. You can set the drive to operate as an RX01 type by some switch settings on a board inside the RX02 disk drive. The controller for the UNIBUS-based machines is the RX211, type number M8256. The controller for the QBUS machines is the RXV21, type number M8029.

• RX50
  The RX50 disk drive also can hold two floppy disks, size is 5.25 inch, but the two "drives" share a common spindle motor and the carriage mechanism moves the heads of both "drives" at the same time. The RX50 drive is very common in QBUS based (small) machines and the QBUS interface controller comes in some versions called RQDX1, RQDX2 and RQDX3, type numbers are respectively M8639, M8639-YB, and M7555. Not so common is the UNIBUS interface RUX50, type number M7522.

• RX33
  The RX33 is a high density 5.25 inch (single) floppy disk drive. The QBUS interface for this drive is the RQDX3, M7555.

• RRD40
  The RRD40 is the first CD-ROM disc drive from DEC. It uses a special "claw" to hold the CD-ROM, and the CD-ROM is inserted with that "claw" into the device. Only the outer "jacket" is pulled out of the drive after the disc is inserted.

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Picture view of disk drive technology advances
One RA81 disk drive, with on top of the RA81 the Fujitsu M2322K disk drive. These Fujitsu disk drives were quite common on the more modern UNIBUS PDP-11's, like the PDP-11/44. The M2322K needs 3 power supply voltages (+24V, +5V and -12V) and the energy requirement is 144 W. The Fujitsu in the picture (with the cover removed to expose the platters and the heads) is dated October 1986. The M2322K disk drive weighs a bit more than 11 kilos and has a capacity of 168 Mb.
And for comparison, here you see that same Fujitsu M2322K disk drive. On the top platter lies a modern IDE disk drive used in laptops, year 2005. This IDE disk drive has a capacity of 40 Gb ...! This IDE drive weighs approximately 82 grams, compare that, its capacity and power requirements with an RA81.   An RA81 weighs a bit more than 67 kilos, has a capacity of 456 Mb and energy requirement of 644 W! But then, unlike the Fujitsu and the IDE drive, the RA81 has its power supply incorporated in the drive ...

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