On Jan 2, 2023, at 11:48 AM, Dan Cross
<crossd(a)gmail.com> wrote:
[Apologies for resending; I messed up and used the old Minnie address
for COFF in the Cc]
On Mon, Jan 2, 2023 at 1:36 PM Dan Cross <crossd(a)gmail.com> wrote:
>
> On Mon, Jan 2, 2023 at 1:13 PM Clem Cole <clemc(a)ccc.com> wrote:
>> Maybe this should go to COFF but Adam I fear you are falling into a tap that is
easy to fall into - old == unused
>>
>> One of my favorite stores in the computer restoration community is from 5-10
years ago and the LCM+L in Seatle was restoring their CDC-6000 that they got From Purdue.
Core memory is difficult to get, so they made a card and physical module that could plug
into their system that is both electrically and mechanically equivalent using modern
semiconductors. A few weeks later they announced that they had the system running and
had built this module. They got approached by the USAF asking if they could get a copy of
the design. Seems, there was still a least one CDC-6600 running a particular critical
application somewhere.
>>
>> This is similar to the PDP-11s and Vaxen that are supposed to be still in the
hydroelectric grid [a few years ago the was an ad for an RSX and VMS programmer to go to
Canada running in the Boston newspapers - I know someone that did a small amount of
consulting on that one].
>
> One of my favorite stories along these lines is the train signalling
> system in Melbourne, running on a "PDP-11". I quote PDP-11 because
> that is now virtualized:
>
https://www.equicon.de/images/Virtualisierung/LegacyTrainControlSystemStabi…
>
> Indeed older systems show up in surprising places. I was once on the
> bridge of a US Naval vessel in the late '00s and saw a SPARCstaton 20
> running Solaris (with the CDE login screen). I don't recall what it
> was doing, but it was a tad surprising.
>
> I do worry about legacy systems in critical situations, but then, I've
> been in a firefight when the damned tactical computer with the satcomm
> link rebooted and we didn't have VHF comms with the battlespace owner.
> That was not particularly fun.
And there is certainly no simple relationship between age and likeliness-to-still-work.
A couple years ago now, I helped inventory the business space and warehouse of a man who
had had a stroke and would thus not be able to continue running his direct mail business.
But in 2017, he was running a direct-mail advertising business off an honest-to-god
PDP-11/70 and a bunch of ADM-3A terminals. He also had several Vaxen out in his
warehouse, a dozen or so TI Silent 700s, and even an 029 card punch. I think his basic
philosophy was to buy these machines as they were surplussed and use them for parts, and
apparently it worked fine for him until his health failed. I've got what looks to be
a pretty pristine VAX-11/730 from the collection, which someday I will get a beefy enough
110V-220V transformer to run (sure, I have 220 to my dryer, but I'm not going to pay
to have it run to my office), and an RM-80, which is now a nightstand. I would be very
surprised if the VAX wouldn't work with no more than minor capacitor work. I also
snagged a Sun 9-track tape drive which came from NOAO and is back home in the correct
building, if not the correct office. It's a coffee table now, because I have no
half-inch tapes I want to read. If someone does, well, it still powers up and spins the
reels. Someone else can sacrifice the goats to get whichever flavor of SCSI it speaks
talking to something modern.
My annual Elvis' Birthday Party is coming up, which is really a boardgaming and
retrogaming party, so I'm going through my stuff trying to figure out what I want to
have in Display Mode as guests arrive. A lot of my mid-90s-through-mid-2000s stuff
doesn't work anymore, like the original Xbox, and the G5 powermac that suffered from
the capacitor plague. But my 80s consoles and 8-bit computers are mostly basically
working fine. The blue electron gun on my Bondi Blue iMac has failed, which is sad, the
better-built 90s workstations are OK, although the CMOS battery on the SparcStation 10 is
long-dead, and the power supplies on pretty much all the Microvax 3000-series need rework
(but the VAK4kVLC is running fine, so there is a real VAX to play with). But in general:
both machines and magnetic storage prior to 1995 have a good chance of still working (for
very occasional duty, anyway), and then there's a decade or so where it's
probably dead, and then newer than that is OK again.
These things are all extremely fun to play with, but honestly I only ever dust them off a
couple times a year. For more-routine retrocomputing jobs (like porting Frotz to
TOPS-20), well, emulation doesn't cost me nearly so much electricity, I don't
have to deal with fan noise, and I'm not worried about some capacitor somewhere
giving up its magic smoke, or just old solder joints finally cracking apart. Because of
the magic of Moore's Law, I can run several 36-bit systems at once on a (back in the
good old days, when you could actually get them) $50 Raspberry Pi.
Note that MetroTrainsMelbourne ended up with PDP-11-on-a-board plugged into Windows XP
systems, and some sort of ISA-bus-to-Unibus converter. I wonder what they're doing
now? It's always the peripheral support that keeps you running on the original
hardware, and from the description and the age of the system I bet the VDU serial links
were pretty tightly coupled to the rest of the timetable generator, and I bet that's
the hard part to reengineer with equivalent functionality. Me, I would have spent the
second 5 years of the extension project paying someone to implement an equivalent (but not
necessarily bug-compatible) scheduler and some sort of
message-bus-over-TCP/IP-to-small-form-factor-PCs-hidden-behind-HDMI-TVs for the display
units, in parallel with the existing system, with particular attention to decoupling
production of the schedule data from delivering it to the remote users, so when that 10
years was up, I'd have had something I was confident in switching to that would be
cheaply maintainable for a while, and where I could upgrade the display and compute tech
individually. But I also suspect management didn't agree to spend their money that
way.
Adam