[HECnet] PDP Ignorance

[Johnny Billquist]

On 2011-07-14 22.53, Steve Davidson wrote:
Mark,

Rare - probably depends on where you can look! :-)

Indeed.

RT-11 will run on any of the PDP-11's.   The RSX-11 family of OS's has
specific requirements about memory amounts and memory management thus
the SPD should be reviewed.   RSTS/E (and M+) require memory management
hardware.   If you can find one, the best is probably the 11/73, 11/83 or
11/93 in a BA23 (QBUS) enclosure.   These come in either 4, or 8-slot
backplanes.   If you really want to experience pain in your electric bill
then the BA123 (also QBUS) with it's 645 watt dual power supplies can
double as a winter heater/loud white-noise generator.   These come in a
12 slot backplane configuration.

Actually, RSX-11M will run on just about anything. I think the minimum memory requirements is 32K, but that's about it. You don't need an MMU, or any other fancy stuff, but such a system is not that much fun to run, so I wouldn't recommend it to anyone who is not already very familiar with the system, and have specific requirements.

There is also the diskless RSX-11S, but that requires a remote boot node (either RSX or VMS).

RSTS/E and RSX-11M+ (as well as Unix) do require an MMU, and some additional things to run though.

Size and powerwise, the BA23 with one of the above mentioned CPUs are probably pretty optimal. The BA123 is nice in that you have room for more disks and a much more serviceable box.

The Pro-Series of systems could also be looked at for RT-11 and RSX
(P/OS).   In this space the Pro-380 is probably preferred.   The problem
here is finding a network card (DECNA) that does not cost as much (or
more) than the rest of the system.

A PRO is a nice system in a way, unfortunately, if running P/OS, you'll probably feel somewhat frustrated by the feeling that the system probably can do more than you can figure out how to make it do.
Also, the hardware is incompatible with any other model of PDP-11, which puts some restrictions on you. But you'll get graphics instead. :-)

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.

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

With much more ease, and less cost, yes.

The books you have detail the degree of expandability for each of these
HW platforms (except maybe the Pro).   You will be surprised at just how
much can be done with these systems.   The speed will be another story.

All of these machines have some weight to them.   An emulator will be
much faster and in the end easier to deal with.   When the PLUTO::
machine is running as an emulated machine it is running with NetBSD and
SimH on a 700MHz Pentium-III, otherwise it is a real PDP-11/23+ (22-bit
backplane).   The emulated machine is faster than the real thing, but not
my much.   I was going for similar performance so that when I switch
between the two it wasn't that noticeable/painful to return to the
actual hardware.

Wow, since a 11/23 is a pretty slow machine...

RT-11 Languages (from memory):
    MACRO-11
    APL-11
    BASIC-11
    MU/BASIC-11
    BASIC-PLUS/RT-11
    FORTRAN-IV (FORTRAN 66 STD)
    PDP-11/C
    DECUS-C

There was probably some more languages, although I haven't got much clue about RT-11. I know one of the earliest Prolog implementations was for RT-11.

RSX-11 Languages (also from memory):
    MACRO-11
    APL-11
    BASIC-PLUS-2
    FORTRAN-IV (FORTRAN 66 STD)
    FORTRAN-77
    PDP-11/C
    DECUS-C
    COBOL-81, COBOL-11

Let's see. You forgot Pascal, BCPL, Forth, SIMULA, Lisp (which are other languages I have installed), and I also know of Focal and Dibol, and I feel that I must be missing a few languages in here...

RSTS/E Languages (also from memory):
    The same as RSX-11 for the most part.

Almost a combination of stuff from RT-11 and RSX.

	Johnny