
PiDP-11: Recreating the PDP-11/70 - jws
http://obsolescence.wixsite.com/obsolescence/pidp-11
======
__david__
It's funny to see the nostalgia for that when I know people of the time who
went to great lengths to get rid of the clunky bit interface. My dad built a
pdp-11/34 and replaced the bit interface with a numeric keypad and some 7
segment displays. You still had to enter bootstrap code but you at least
didn't have to do it bitwise!

Later he built an 11/70 and replaced the whole front console with a bootstrap
terminal (with custom CRT driver if I remember correctly—ie, not off the
shelf). That one you just had to hit the "boot" key and it would load the
bootstrap code and do everything for you.

~~~
crististm
It just goes to say that current systems lack something. We cannot always put
the finger on what it is and backtrack to where we think times were better.
Using these machines is the closest real thing to going back in time.

I can see this with both powered systems like Symbolics LM or with smaller
ones like PDP11, Spectrum, C64 or others: we lack the context in which they
existed. We cannot bring them back today and use them as primary systems
because we don't have the context that need those machines. They are doomed to
be played a little and to be sent back to attic.

Current systems lack the context of the old times and old machines are frozen
in a time that is not fit to today's needs.

~~~
rbanffy
It depends on how far into the past you want to go.

Not so long ago, my desktop was an IBM PowerPC running AIX with most (if not
all) the heavy lifting being done on a laptop (that lacked a 2048x1576 22" CRT
screen and a model M keyboard).

With X and an ethernet port, it was a perfectly usable machine, provided I
logged on to the "server" on the other desk.

One of the projects I will do one day (no time now, sorry) is a board for
Apple II's that would take over the bus and use the text mode and keyboard as
the console of a Raspberry Pi-like board. It's perfectly doable to take over
the 1 MHz bus and use the compute as Z-80 boards used to.

OK. That's not exactly usable as a work machine (not nearly as usable as the
IBM, at least), but it'd be incredibly cool to be able to use a //e Platinum
to work. Even if for a short while.

The exercise of traveling back in time is often not as much as to use the
machines for actual work, but to experience them as tools to learn about the
context where they existed - the time we had manuals printed in paper, where
we would debug (and edit) programs on printouts on wide carriage paper with
green bars - to (re)learn the lessons others learned before us that we can
still benefit from.

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amirhirsch
After I graduated, I built a PDP-11/70 replacement in FPGA to replace the
controllers of old nuclear reactors. We designed it to be a fully compatible
hardware drop-in replacement passing the full suite of tests with exactly
accurate fault results. This included properly ordering floating point unit
errors followed by a stack error -- due to pipelining the FPU error is
supposed to be caught after the stack error. Additionally no other emulator
exactly produced the same partial results of a division failing with an
overflow.

~~~
rbanffy
How hard would it be to compile the HDL into C that could run in an emulator?

A couple years back I was looking into MESS code and observing how ordered it
is and how much work would it be to do the reverse - starting from known
modules (CPUs, CRTCs, etc) to compile it into an HDL.

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JoeAltmaier
My old college machine! Brings back memories of all the hacks it took to get
anything useful written in 64K.

I knew it was history when I was in Los Alamos at a surplus store in the 90's,
and they had one _out in the rain in the parking log_. Not even worth dragging
under cover.

~~~
jacquesm
We got one for free from the Nikhef, the Dutch particle research center. Took
forever to get it reassembled because it got banged around too much in
transport but once it worked it was pretty neat. It came with a very good PCB
routing and placement package, as well as a tablet and a graphics terminal.

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WalterBright
You can get Empire ([http://classicempire.com](http://classicempire.com))

for the PDP-11 here:

[https://github.com/DigitalMars/Empire-for-
PDP-11](https://github.com/DigitalMars/Empire-for-PDP-11)

~~~
WalterBright
I rue the day when I gave away my H-11. It's the background pic on my twitter
account:

[https://twitter.com/WalterBright](https://twitter.com/WalterBright)

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jacquesm
That's got to be one of the coolest RasPi cases in existence. And at $250 it
may seem a bit steep but with the volume they made and the amount of time put
in it is actually a steal.

~~~
fyfy18
Would love to build one, but with shipping and customs fees it’s going to be
almost $400 sent to Europe. Maybe someone will come up with one I can 3D
print?

~~~
NeedMoreTea
Even at that cost getting it to the UK I'm ridiculously tempted.

Funny thing psychology, I wont pay $1k for a phone, but $400 for a RaspPi
case, thinking about it... :)

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Aloha
I'd find this a whole lot more interesting if it was a real PDP-11
implementation.

~~~
tyingq
It works with an FPGA based PDP-11 emulator as well:
[http://pdp2011.sytse.net/wordpress/things-are-
moving/](http://pdp2011.sytse.net/wordpress/things-are-moving/)

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jonatron
I made something similar on a smaller budget, see jonatron.me . It's nowhere
near as nice looking though. And you'd have to use a different emulator to
make it do more than a couple of basic blinking light test programs

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crispyambulance
I've always wondered, what _are_ those large groovy switches on the front?

They're just numbered with integers [0..21, colored in groups of 3 presumably
for octal]! are they seriously for bit flipping??

~~~
OliverJones
21 bits ... allows front panel access to more than the 16 bits of the machine
registers. smokin'!

~~~
ch_123
The /70 had a 22-bit address bus, so I assume that switches 16-21 didn't have
any effect unless you were entering a memory address.

~~~
jtlienwis
I read something that said Ken Olsen found these switches on an old model
washing machine and thought they would be great on the PDP machines.

~~~
jtlienwis
I think it might have been the 1957 Philco-Bendix Duomatic washer/dryer front
switches that inspired the PDP-11 panel.

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ChicagoDave
Give me this and anything close to an LA-32 paper terminal and I’d be in
nostalgia heaven.

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OliverJones
To use this do we have to put in the bootstrap sequence with the switches? :-)

~~~
kabdib
Don't worry, the bootstrap code is muscle memory after a week or two of
booting the system.

~~~
Taniwha
so true

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dboreham
I have an almost complete set of /70 parts in the closet, but no front panel.
By the time I started buying parts people had realized the panels looked cool
and were paying high $$ for them to make wall-art!

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octorian
I actually built this kit recently. I'm now gradually building a collection of
these front-panel-simulation machines. (Last year, I built his PiDP-8 kit.)

~~~
VLM
I'm only familiar with the altairduino, which works pretty well on my desk.

If you know of any other than those three, please post?

I think an IBM 1130 would be totally achievable and fun. A 360/91 might be a
little optimistic. You can clearly see the influence on Star Trek original
series in something like a 7090; someone who doesn't know retrocomputing would
probably accuse a 7090 as being a trek prop.

~~~
octorian
I actually have an Altairduino kit sitting in my closet, waiting for me to get
around to building it. :-)

So far, these are the only three kits I'm aware of.

At VCF-West for the past year or two, the Computer History Museum (in Mountain
View, CA) has been showing off a similar project they've been working on with
an IBM 1620 Jr front panel. However, that's definitely not something you'd
make a kit out of. But, as part of it, they've figured out how to convert a
modern'ish electronic typewriter into a teletype.

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zentiggr
uMatrix has a horrible time with the crazy amount of bits and pieces to be
temporarily approved for wix sites.

Not that I need to dive into 11/70 trivia... played around on them when my dad
worked in Maynard, had front panel banks as rocket ship controls etc laying
around the house. (Good times when your parent is on the bus test group and
helping out on weekends :)

