DEC RK07 drive interface specs wanted

From: Patrick Finnegan <>
Date: Fri May 14 00:41:49 2004

On Thursday 13 May 2004 21:09, Tom Uban wrote:
> I disagree about MSCP making more sense. If the controller is to be
> used on older pre-MSCP operating systems, then MSCP will be useless.

<sarchasm>But who'd ever want to run an OLD os on classic

Seriously, you've got a point, and I hadn't thought about that fact
before. Part of the issue is that I don't have any of that "old"
versions of software/OS that won't talk MSCP.

So, what devices would give us the largest range of possibilties for
software compatibilty at the larges size?

If we're to use a microcontroller to run this board, then it'd be
possible to have "changable firmware", and either change it to emulate
the type of device you want, or to emulate multiple devices. On second
thought, you probably don't need a microcontroller for that, but it
seems easier than going the FPGA/PLD route to do it.

<reaches for pdp11 peripheral handbooks>

In 1970 pdp11 handbook:
- no disks, just a teletype and papertape reader are listed.

Added in 1973/4 pdp11 peripherals handbook:
- RK11/RK05 - 2.4MB disk pack
- RP11/RP03 - 40MB disk pack

Added in 1975 pdp11 peripherals handbook:
- RP04 - 100MB (presumably same RP11 interface as RP03)

Added in 1975 pdp11 peripherals handbook:
- RL11/RL01 - 5MB disk pack

Added in 1978/9 pdp11 peripherals handbook:
- RK06 - RK11, 14MB disk pack
- RK07 - RK11, 28MB disk pack
- RM02/03 - RM11 MASSBUS interface, 67MB disk pack

Added in 1981/2 pdp11 peripherals handbook:
- RL02 - 10MB disk pack
- RP06 - 176MB disk pack
- RP07 - 516MB winchester
- RM05 - 256MB winchester
- RM80 - 124MB winchester

So, it looks like to me the best choices would be an RK11/RK05(06,07),
an RP11/RP04(05,06,07), an RX11/RX01 and and RL11/RL01(02) emulator.
If I were to pick a single choice right now, I'd probably pick the RP11
controller, for the breadth of possible sizes (from 40MB in 1973 to
516MB in 1981), and put RL11 as a second choice, simply because I've
got one. :) RK11/RK05 seems too small to be worthwhile, but the RK06
and RK07 aren't bad sizes.

Now, I haven't looked much into complexity yet, but at first glance
through register descriptions, RL11 takes the cake on simplicity on
just 4 registers, RK11 is middle-ground with 7, and RM11&RP11 are the
most complex, with at least 20 registers.

So, as a first try, I'd probably go for the RL11 for simplicity and then
once that was working, try for the RK11 or RM11/RP11 interfaces. These
all seem a lot simpler than MSCP (UDA50/KDA50) interface emulation, and
support media that should be "large enough" for most people (1/2GB).
In fact, the drive in my VAXstation 3200 is only 650MB, and it feels
big with VMS 5.3 on it.

For the actually data storage, I think you'll want to use flash or a
writeable hard drive (perhaps even a 2.5" laptop IDE drive mounted on
the UNIBUS controller card). It seems novel to have a 8 (emulated
drive) x 516MB (4GB total) UNIBUS storage card that takes up a single
SPC slot.

Hey Tom, have you started at all on your RK11 emulator? Want to compare
notes on this?

Purdue University ITAP/RCS        ---
The Computer Refuge               ---
Received on Fri May 14 2004 - 00:41:49 BST

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