[TUHS] Unix v5 and beyond

Dave Horsfall dave at horsfall.org
Sun Jul 13 15:02:20 AEST 2014

On Sun, 13 Jul 2014, Mark Longridge wrote:

> I'm interested in comparing notes with C programmers who have written 
> programs for Unix v5, v6 and v7.

I'll try and remember, but this was about 40 years ago...

> Also I'm interested to know if there's anything similar to the scanf 
> function for unix v5. Stdio and iolib I know well enough to do file IO 
> but v5 predates iolib.

Not a chance; about all it had were the system calls.  Portable I/O came 
with either Edition 6 or PWB, then Standard I/O replaced it.  I could be 
wrong, of course...  Ed5 may have had getc()/putc() - I dunno.

> Back in 1988 I tried to write a universal rubik's cube program which I 
> called unirubik and after discovering TUHS I tried to backport it to v7 
> (which was easy) and v6 (which was a bit harder) and now I'm trying to 
> backport it to v5. The v5 version currently doesn't have the any file IO 
> capability as yet. Here are a few links to the various versions:
> http://www.maxhost.org/other/unirubik.c.v7
> http://www.maxhost.org/other/unirubik.c.v6
> http://www.maxhost.org/other/unirubik.c.v5

Hmmm...  I must have a peek at them, and for laughs port the v7 one to 


> My initial impression of Unix v5 was that it was a primitive and almost 
> unusable version of Unix but now that I understand it a bit better it 
> seems a fairly complete system. I'm a bit foggy on what the memory 
> limits are with v5 and v6. Unix v7 seems to run under simh emulating a 
> PDP-11/70 with 2 megabytes of ram (any more than that and the kernel 
> panics).

Well, complete for the day...  Memory limits were basically 64kw for each 
space (I'm not even sure whether Ed5 had sep/id space).  The irony of the 
PDP-11 was that it could support virtual memory in theory, but simply 
didn't have enough address registers.  Or am I thinking of some other box?

> Also I'd be interested in seeing the source code for Ken Thompson's APL 
> interpreter for Unix v5. I know it does exist as it is referenced in the 
> Unix v5 manual. The earliest version I could find was dated Oct 1976 and 
> I've written some notes on it here:
> http://apl.maxhost.org/getting-apl-11-1976-to-work.txt

Gawd; I'd love to see APL again!  I used it on the IBM-360.

> Ok, that's about it for now. Is there any chance of going further back 
> to v4, v3, v2 etc?

Very little; Ed5 was the first public release, so unless an old-timer has 
them squirreled away somewhere...

-- Dave

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