DEC RK07 drive interface specs wanted

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Fri May 14 18:31:57 2004

> > It also depends on what you want to do. To me, a classic computer system
> > is more than just the CPU. The peripherals are part of it as well.
> > Running a PDP11 with flash memory mass storage is not the same as running
> > one with a demountable hard disk.
>
> While in principal I agree, in years gone by, I was unable to do more than
> play-load 2BSD on a real 11/24 because my largest Unibus disk (that wasn't

Hmmm... Well, if you want to run unix, you might as well get a PC :-),
and actually, I do take the point supported by some people here that if
you're more interested in the software side of things then you might as
well run the old software under emulation.

I am unashamedly a hardware person. But that love of hardware goes way
beyond just the CPU. I really do want the old peripherals too. Heck, I
even use an old VT55 (a real, DECscope, VT55) as my PDP11/45 console. A
PC running a terminal emulator is not the same. Although admittedly I do
find my HP95LX a very useful pocket terminal for testing/debugging things.


> on a UDA-50) was and still is RL02s on an RL11. These days, I have bigger
> Unibus CPUs (11/44, 11/70), but in terms of pre-MSCP disks, 10MB is still
> a limit for me (fortunately, I can get around this with 2.11BSD on the 11/44
> or the 11/70, but 2.9BSD was it for non Split I&D machines)
>
> Even though I appreciate and admire the older disks, I'm pretty much stuck
> with RK05 and RL01/2. I'd love a solution that emulates _some_ DEC disk

I am sure I have at least one Unibus SMD controller that emulates the
RK611.... Are they really that hard to find. And I have managed to use
Q-bus disk controllers on my 11/45 system (certainly the RLV11) via a
DW11-B interface. A bit of a kludge, but it works.

> the bill. If I weren't worried about compatibility, I'd probably just
> go down to the basement and hack something into a Unibus COMBOARD (68000-
> based communication controller w/DMA interface, 16K/32K EPROM, 128K RAM,
> 5025 sync UART, 6821 PIA...) I've thought about those stick-in-the-socket

\begin{pedant}
How can you have a synchronous UART??? Don't you mean a USRT (or USART)?
\end{pedant}

:-)

> interfaces for slotless Amigas - both IDE and SCSI are available. The
> one thing that stinks is that for a disk controller, a sync UART is pretty
> much useless... I'd consider swapping that out for some other chip. We

Oh, I don't know. It was pretty much the main chip of most hard sectored
floppy disk interfaces :-)

> It's pretty well documented in the DEC "Bus Handbook" - I have it on paper
> at home, and I'm pretty sure it's on bitsavers - I know I've seen it online
> somewhere.
>
> We just went with the DEC bus chips, not an option these days, though, unless
> like me, you happen to have a pile of 8641s and DC013s...

Unless your Unibus is really loaded, you can get away using open-collector
TTL chips as drivers and TTL schmitt triggers as receivers. Of course you
still need lots of chips for the bus address counter, etc.

-tony
Received on Fri May 14 2004 - 18:31:57 BST