[HECnet] PDP Ignorance

[Johnny Billquist]

On 2011-07-15 03.24, Zane H. Healy wrote:
At 1:03 AM +0200 7/15/11, Johnny Billquist wrote:
RSTS/E and RSX-11M+ (as well as Unix) do require an MMU, and some
additional things to run though.

RSTS/E offers some real challenges if installing on real hardware. While
I've installed RT-11 and RSX-11M+ off of CD-ROM, I'm not sure it's
possible with RSTS/E. Another tricky situation I ran into was that
RSTS/E would install off 4mm DAT tapes, but the layered products,
especially DECnet/E wouldn't.

I seem to remember that some installation pieces in RSTS/E actually requires that tape drives identify as the "correct" models, or RSTS/E will refuse. I don't remember the details, but I think John Wilson documented in the e11 manual.

Disks on real hardware will be small and slow (an possibly expensive).

Well, not neccesarily true. There are SCSI controllers, and large fast
disks. But they are often not free.
How large disks you can actually use will also depend on what OS you
run, with RT-11 being the most limited.

What does the availability of disks look like for someone looking to put
together a PDP-11 at this point? Unless you're like a lot of us here,
and have been doing this for a long time, and built up a supply of
spares years ago, such things can be hard to come by. Even Narrow SCSI
disks are getting harder to obtain.

I have not had any problems with rather modern SCSI disks. No need to get narrow disks. They are supposed to be backwards compatible anyway.
I have some wide RZ disks in storageworks bricks on my 11/93 as well as my 11/84.
Just don't hope for anything if you have differential SCSI.

I also have RA disks running, and RL, but nothing else. I don't like RD disks because they are small, and *slow*, if you are even lucky enough to get them running.

If you have *ANY* third party controller, you're likely to have a
slightly easier time. Any MFM disks will be hard to find, and unlike
when I was putting my first system together ESDI disks are likely to be
even harder to get. While a SCSI board might set you back a nice chunk
of change, it's likely to be the best path. Besides then you can hook up
a CD-ROM drive.

Yes.

On emulated systems they can be much bigger and many many times faster.

With much more ease, and less cost, yes.

Back in the 90's I swore running on real hardware was the way to go.
Now, with a nice collection of spare parts, I think Emulation would have
been better! Not as fun, but a Linux box running an emulator takes up a
lot less space! Thankfully that's the route I went with the PDP-10...

He. A PDP-10 takes a little space, even for a KS...

But since this is now starting to spin off into rather much PDP-11 stuff, maybe we should get this to some other place as well?

Anyone have any good suggestions? Otherwise I'd suggest alt.sys.pdp11 on internet news.

	Johnny