PDP 11 Victory!

From: Ethan Dicks <ethan.dicks_at_gmail.com>
Date: Sun Feb 13 00:06:18 2005

On Sat, 12 Feb 2005 19:39:49 -0800 (PST), Vintage Computer Festival
<vcf_at_siconic.com> wrote:
> Oh, I am stoked.
> I just finished a day long saga of getting my PDP 11/23+ working with RX02
> and TU-58 support.

Nice. Congrats!
> Howard Harte hooked me up with a CD with everything I needed on it. I had
> the TU58 simulator plus a bunch of boot images to choose from. I used
> John Wilson's *EXCELLENT* PUTR utility and found the right boot image
> (with DY and DD drivers, plus PIP, etc.)

Which TU58 simulator is this? Does it have its own web page?

> I restarted, specified DY, and lo and behold, RT-11 booted off the floppy!
> Woohoo!! This is so gawd damn cool! My arms were flung up in a final
> private display of victory.

That is pretty much how this stuff _normally_ goes... take it step by step and
there are few surprises... I remember learning different DEC platforms (OS/8,
RT-11, etc.), and having similar euphoric experiences.
> I love PDP-11's!!!

Hear, hear!
> Next projects:
> - find a SCSI card so I can hook up SCSI devices (ZIP drive)

The holy grail of PDP-11 users.

> - Hook up some other drives (RK, RL) and play around with them

Those are fun. I personally have more time spent with RL-based
PDP-11s than RK-based PDP-11s... in the Qbus case, RLV11s were cheap
when I got into all of this, because
they are 18-bit, not 22; and as a two-card set that requires a
CD-interconnect backplane,
they only work in certain boxes. RLV12s were once several times the
cost of an RLV11,
especially because they worked in MicroVAXen, and they worked out of
the box with VMS.
These days, though, it might be easier to _find_ an RLV12, and it
_will_ work in an 18-bit

Again, in terms of Qbus, for RK05s, there's exactly one choice - the
RKV11D - a 4-slot
box the size of one of the models of PDP-11/03 (I forget the enclosure
designation), with
the same card set as an RK11D, but with cables to a paddle card that
sits on the (18-bit)
Qbus. There's another cable that goes from the RKV11D to a mostly (or
entirely) passive
paddle card that sits in the first RK05 drive in the chain.

As for drives, I have rarely had to mess with RL01 or RL02 innards -
they tend not to break much (head crashes aside, but those are rare,
too)... I have had to do some mechanical refurbishment from time to
time, but that's usually cracked lids/hinges, broken circuit breakers,
and pretty obvious stuff. RK05s, in my experience, are somewhat more
They _really_ need a good air purge and dust wipe-down before risking
any packs (the
air path in an RL01/RL02 is pretty simple and streamlined; most of the
drive innards are
in the air path of an RK05)... also don't forget to (un)lock heads on
*both* kinds of drives
(you have to get the lid open on the RL drives to get access to the
head lock, and you
have to remove the entire top cover of the RK drive to reach its
lock). Another drive
issue is the NiCd pack that retracts RK heads during power failure -
you only have to need
it to kick in once to painfully regret not replacing it _before_ you
start mounting packs.
The RL drives have no such pack, BTW.

I have never had to fiddle with RL heads or alignment (they use
embedded servo data),
but the RK drives are a different story... there's a glass reticule
that's part of the track
positioner feedback look - these drives can be aligned (and might need
to be), and
if the lightbulb that illuminates the reticule burns out, things won't
work right (can't
remember if you get a fault light, or the pack won't mount or what).

What else... oh... the orange rubber/plastic air ducts in the RK can
get *really* brittle.
Also, fresh absolute filters would be nice to have, but I have no
earthly idea where to
get them anymore.

All that having been said... I like the RL drives, but there's
something interesting about
seeing how the RK drives do what they do - you _can_ run them with the
top cover off
(and have to, to align the heads), so you can see things work.
Whatever you do, do
_not_ get your fingers between the voice coil magnet and the flange at
the end of the
moving voice coil - a seek to the edge of the disk will catch your
finger faster than you
could possibly jerk away, and ISTR the clearance is on the order of 1/8" (~2mm).
The voice coil will win; your finger will lose.

> - Get my 11/34 up and running which has RK05 and RK05F drives in the rack
> and is otherwise a very complete system with 16 serial ports (PDP-11
> hacking party anyone? ;)

What OS? For multi-user, it would probably want to be 2.9BSD (but
memory would be
tight), or some flavor of RSTS (keeping in mind memory issues there,
too). I suppose
one could fire up an EduSystem and run BASIC on the terminals...

Congrats again; you've had some great successes with one of the greatest
architectures sold... plenty more fun to be had there.

Received on Sun Feb 13 2005 - 00:06:18 GMT

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:37:37 BST