[TUHS] merry christmas

Nick Downing downing.nick at gmail.com
Mon Dec 26 07:44:13 AEST 2016

Yeah :)

I'm only an occasional contributor to the list, more of a lurker really
since I was pretty busy this year. Well I promised a guy on the list some
Unixy stuff that I had and have been gradually going through it and putting
it on bitbucket but have not had time to write it all up yet.

But I wanted to jump in and say something to the new people who joined the
list owing to whatever was the recent media coverage we had. Welcome and
all that. But IT ISN'T NECESSARY to have been around at the inception of
Unix to get into it and to learn about the retro flavours, come up to speed
in PDP-11 asm or learn about the old filesystems or whatever it is that
floats your boat :)

Personally when I discover something AWESOME I immediately want to take it
apart and learn EVERYTHING about it. For me in the case of Unix, I quit my
job in about 2005 and had about 3-6 months of downtime while considering my
next moves, I had next to no money so I could not really leave the house,
but I had a houseful of computers and a 33.6k modem so I set myself the
task of learning about this mysterious Linux thing. I downloaded Slackware
4.0 onto a set of floppies and followed the Linux From Scratch instructions
to build and bring up my own Linux flavour from that.

This was very educational and it highlights the main point of my post which
is you MUST GET YOUR HANDS DIRTY, reading ancient source code is fine but
one doesn't retain much info unless one reads for a purpose (why the hell
won't this RK05 boot my system etc). So anyway a lot of things still
remained a bit mysterious after my LFS adventures since they are that way
for historical reasons, and I found myself bringing up earlier Unices on
simh to take a peek and joining this list etc.

But as I said one does not retain much unless one has a purpose and
probably the project that taught me the most was bringing up someone's
hobby Unix V7 clone on a cash register motherboard from the equipment I
used to sell in my day job. The software is called UZI (Unix Z80
implementation). I remembered waaay way back when I was pottering around
with CP/M and enhancements like ZCPR3 I saw this mentioned in a newsgroup
or similar, with a description that it runs Unix in 64k by loading the
kernel in first 32k and a process in second 32k and uses "total swapping"
i.e. it multitasks or implements child processes by writing the second 32k
to a swapfile on floppy disk and loading it back in later. This sounded
very intriguing and I wanted to try it out. So, years after reading this
newsgroup post I obtained it and compiled it (using the IAR compiler we
used for cash register development) for my cash register.

Long story short the thing was soon utilizing various kinds of bank
switched memory available in this cash register (which had a Z180 CPU and
hence behaved like a Z80 with an MMU and other integrated peripherals) and
had a network stack from Phil Karn's NOS, it had lots of communication
ports for barcode scanners, printers, modem etc and I had them running SLIP
and communicating with publicly available FTP servers, I used to use
mirror.aarnet.edu.au for testing and my cash register could download small

I became frustrated with the limitations of both UZI and NOS and decided to
port 2.11BSD to the cash register as the next step, my goal was (a) make it
cross compile from Linux to PDP-11, (b) check it can build an identical
release tape through cross compilation, (c) port it to Z80 using my
existing cross compiler. Well I don't think I got all the way through this
ambitious programme before putting it aside and starting a new job but I
sure as hell learned a lot about building PDP-11 Unix. The buildsystem is
complicated and contains its share of hacks, but overall much simpler than
something like gnu's configure/make or cmake or etc.

Although I was not around for early Unix (was probably a 10yr old taking
apart an Apple II and trying to learn 6502 code without the benefit of an
assembler in 1985 when stuff like SVR4 was popular) I probably know as much
about its internals and development environment as many people here, due to
having got my hands dirty, albeit 30 years later. In fact I FEEL LIKE I WAS
THERE. So my suggestion to newbies is, get your simh on, and tackle some
interesting project such as reconstructing an early source for something
from the fragmentary surviving pieces, backporting some useful tool to an
earlier Unix, or whatever. Just get your hands dirty and it will be an
infinitely rewarding experience. Because Unix is AWESOME. Retrocomputing is
AWESOME. Simulators are AWESOME. :)

cheers, Nick

On Dec 25, 2016 2:17 PM, "Larry McVoy" <lm at mcvoy.com> wrote:

> As Neil Young said when he played with the band, it's been of one of
> the great joys of my life to be here with you (yeah, I paraphrased).
> As a kid who wanted to be at Bell Labs, a student who got the troff
> manual and used it for the next 30 years, a student who got an account
> on the vax 11/750 that had the BSD source on it and learned so much,
> I just want to thank all of the Bell Labs people for being here and
> Warren for putting this list together and for Unix teaching me so much.
> If I could have one thing for Christmas it would be bwk joining the list.
> I did some extensions to awk and asked him about it and he tarred up
> ~bwk/awk and sent it to me.  I've got the awk source and the book source
> in english and french (I think).  Brian is awesome, it would be cool to
> have him on this list.
> All that said, I super grateful to be here amongst the people who were
> there when you got an image from Ken.  You guys are lucky.
> --lm
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