On Fri, Oct 14, 2016 at 10:33 AM, Noel Chiappa <j...@mercury.lcs.mit.edu> wrote:
>     > From: Jason Howe
>     > I really really want to aquire a PDP-11 ... Given the price of these
>     > things in the world right now...
> If you're willing to live with a QBUS machine, and not a UNIBUS one, it
> doesn't necessarily take a mountain of money

Agreed.  I see Qbus PDP-11s offered from time to time for a few
hundred dollars down to free.  I'm helping someone restore a 42" cab
with a MicroPDP-11/73, a second BA23, RL02, RQDX3 (missing drives
because they were removed and destroyed prior to sale - a common
thing), TSV05 magtape, 10 serial ports... I think it was a recent
State Surplus auction that went for under $100.

> I've bought 11/23 CPU boards for as little as $40 recently, and memory and
> serial interface cards for console are on the same order of money. And I got
> a BA11-S box, complete with power supply and backplane, for a little over
> $100, IIRC.

No disagreement with those price points.  Those are the kinds of
numbers I see too.

> The real hangup is mass storage; the older drives, at least, are all real
> money now.

So very true.

In the case of the PDP-11 and RT-11, one modern solution to this is
use a second serial port for an emulated TU58.  Many of the Qbus
PDP-11 CPU cards have 2 serial lines, and for those that do not, the
DLV11-J 4-port card is common and inexpensive.  With a solid-state (SD
card) storage for emulated media, there's no seek time, and the
transfer time via serial really isn't all that bad.  It's not as fast
as a hard disk, but it's a solid, inexpensive way to start.

> I don't know about the later ones (from the uVAX era), those seem
> to be cheaper, but I don't know anything about them.

Many 1980s Qbus PDP-11s have an RQDX3 which will talk to RX50/RX33 and
5.25" floppies - again good for RT-11.  The RQDX3 talks to the RD31
and RD32 (ST-225 and ST-251-1, some of the most common smallish
ST506/ST412-interface drives, though nowhere near as plentiful as they
once were).  Another common storage solution for small systems was the
RL02 with an RLV12 - up to 4 drives, and still one of the more
plentiful storage devices from the era, though owing to brute-force
deinstallations and copper scavenging, it seems that cables could cost
you more than drives and controllers.  Storage over 40MB on the small
end is indeed somewhat tough to come up with.  QDA50 controllers seem
to be not difficult to acquire, but the drives to go with them are
heavy and, especially the notorious RA81, often cantankerous (all of
this is worse on the Unibus where there isn't even the option of the
RQDX3 for modest-sized systems).

For a "serious" Qbus system, the present solution seems to be looking
for a Qbus SCSI card at $250 or under, then using an old 3.5" SCSI
drive or a SCSI-IDE adapter and any (nearly) modernish desktop hard
drive or  a CF card or SD card.


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