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#pdp11

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MUDs and the ability to reload new server without dropping connections (a “hotboot”)…

boston.conman.org/2025/02/11.2

…reminded me of an old RSX-11M application from an aeon ago, running part of a state government.

The app was too big for the PDP-11 (a common problem, as 32KW wasn't all that much even then), so the app removed the operating system from the computer, and ran, well, standalone.

Yes, you could do that back then.

That all worked swimmingly until somebody pressed ^C control-C on their terminal session, and the terminal driver then trapped into, well, nothingness.

Since the app code was too big for the PDP-11 it was running on, that smaller PDP-11 was shut down, the bigger local PDP-11 was switched over and re-booted and the app code loaded, and the bigger PDP-11 was then powered down.

The operator then pulled the core memory out of the bigger PDP-11, walked it over to the smaller PDP-11 and plugged it into the backplane, toggled in the address of the app's main loop onto the front panel switches, and toggled “go”, and off the smaller PDP-11 went running its too-big app.

Yeah, you could do a simple form of app checkpoint-restart with core memory, given core was persistent. And yeah, a bigger PDP-11 would have been helpful.

(Yes, SC was a creative administrator of those PDP-11 boxes. Swapping core never would have occurred to me.)

The Boston DiariesI never got the memo on “copyover servers” - The Boston Diaries - Captain NapalmI never got the memo on “copyover servers”
Continued thread

1/ Just because, here's my LSI-11 desktop - It works, they used much better capacitors in those days.

Way back when, the LSI-11 was often used to teach people Operating Systems and Compiler Design, and in my CS degree in 1986 we'd fiddle with #MINIX on these things, and deal with re-writing different low-level #UNIX things. Life was much easier with only 50 instructions to work with.

#DEC#Digital#PDP11
Replied in thread

@mini @Eva_RespectExistence
Uh, auch nicht gemerkt. Gutes Auge.
Ach, hör mir auf. Wir haben mal mit fünf Personen zwei Tage lang weißes Papier in braungefärbtes Wasser getunkt, damit in einem Film das Papier schön alt aussieht.

Mein Argument "Aber das war zu der Zeit doch überhaupt nicht so gelb" wollte Keine*r hören.
Die Leute wollen wohl diese Patina. 💁

Der #PDP11 war z.B. eigentlich ein #AS400.
Wäre mir nicht aufgefallen.
starringthecomputer.com/featur

starringthecomputer.comStarring the Computer - 23Computers in movies and television shows

Sean Haas of @adventofcomputing has a fascinating episode out about #IDRIS, a reimplementation of #UNIX for a variety of early personal computers with #Intel8086, #Motorola68000 CPUs as well as #DEC #PDP11. Bizarrely, the OS seems mostly lost.

adventofcomputing: Episode 149 - IDRIS is Not UNIX

patreon.com/posts/episode-149-

en.m.wikipedia.org/wiki/Idris_

A version of IDRIS that starts from #DOS is available on GitHub, though!

github.com/hansake/Whitesmiths