OT: Language for the ages

[Tony Duell]

> 
> Brad Parker wrote:
> > But I think the language misses the point.  It doesn't matter what
> > language it's written in.  The important question is what will it run
> > on.  There are still pdp-11's out there running applications every day
> > and it doesn't matter what they were written in.  It does matter if the
> > 11/44 power supply blows up, however :-)
> 
> Not much though.  How long would it take to bodge up a working power 
> supply for a PDP-11 of any flavour?  It's not like it's incredibly 
> critical, unlike modern PC motherboards.

I suspect the original mention of 11/44 was done for a reason. The 
PDP11/44 poser supply is very complicated inside, it's really 3 separate 
SMPSUs running off the stame 400V DC supply (rectified mains), with a 
board of control logic at one end to do things like turn off the CPU and 
Unibus power, but beep the memory alive. Oh yes, there's an optional 
battery backup unit for the memory supplies. And even a full-H driver for 
the special cooling fans (and that is also supplied by the battery unit 
if fitted).

However, DEC schematics are pretty clear, and there's nothing that odd in 
the PSU. I think I could keep one going, and repair it in less time than 
it would take to bodge in some modern, less well made and less well 
documented replacement.

However, if you're the sort of peron who'd afraid of coke-can sized 
capacitors charged to 200V, then there's noting that odd about the 
outputs of the 11/44 PSU,. There's a 5V rail (120A or so) for the logic 
and +/-15V rails for the Unibus slots. Another +5V and +/-12V rails for 
the memory (there's no good reason why the 2 5V rials couldn't be linked 
if you're not keeping the battery backup). Maybe a -5V. 

You'd lose the battery backup ability, you'd lose the ability to power 
down the CPU and Unibus but keep the memory on, and you'd better change 
the fans for something more convenitonal (12V DC would be the obvious 
choice). 

But yes, you could bodge in another PSU without too much hassle.

-tony