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An ongoing T-11 project.


Experienced Member
Dec 11, 2010
So I decided to try to use this blog facility as a place to keep a bit of track/history of what is actually now became "the T-11 project", I think we are going maybe a bit too off topic from the thread that started it all so I think a blog could be a better place to continue it.

But first of all a little story about how all this started.

Well I could begin with "I always heard of PDP computers but I never seen/touched one" .. and this enough could be for me to stimulate some of my curiosity, the closest I got to DEC equipment/architecture was a VAX 11/780 we had in our university in Trieste ( a machine at that time I remember as 'UTS882' ) then later on around 1995 when I started to work for a certain company we had some Microvax that was our "main machine" for certain works.

VAX in those times was "the industry king" for "serious industrial applications", I remember "DECNet" long before I ever heard of TCP/IP or let alone internet or such.

Anyway "PDP-11" was a name often coming out into conversation or "hw pub tales" when the times were good and ( some ) people were talking about hw and algorithms down the pub.

Finally I think my first time I ever seen a PDP "in the flesh" ( but behind a glass and not in function ) was in the London Science Museum where they have a PDP-8 in a cabinet.

Then time ago someone put on ebay a set of RT-11 manuals, around the same time for various reasons I was serching some stuff I stumbled across the SIMH emulator, that's been my first time ever I actually manage to see and kinda touch "what a PDP-11 was running/doing/looking like when you were in" as one of the OS supplied with it was RT-11 ( and nobody else was bidding on those manuals ) I found "natural" to give it a go .. I ended up in getting the full box of them for a ridicolous price.

So you can see "indirectly" a "certain path" was building up ...

At some point it does happen I started to work with a person that has the habit to sign his emails with "Sent from my PDP-11" .. I tought it was real but it tells me "Nah it's a joke" but he then explains me all his story and fondness for the PDP-11 as it was the first machine he got a job on writing SW to control a CNC machine that was connected to it .. he has quite a fondness for it.

I was kinda tempted at that point to see if I was able to set up the version supporting ethernet of that SIMH emulator and see if I could have sent him an email from "a real" PDP-11 but then .. "Nah .. even that would be faking .. ".

Time passes then 2 strange "coincidences" happen .. while working on another SW project "inspired by" Intellivision style a "mini blast", turns out the CPU inside the Intellivision console it's "based on" the PDP architecture, it's NOT a PDP cpu but "parts of it" are "kinda like".

But this anyway turns out it was really "too far away" to rensemble any real PDP.

Second thing .. and now it gets "weird" for reasons too long to explain it turns out there's a piece of HW, a full arcade cabinet, that been moved there and there for quite some years until it ended up in a half garage/hay storage in a corner labelled as "semi-trash to get rid of", the only reason it was still there is that it was too big to be thrashed easily.

Now here "in this house HW never dies" I was quite surprised that thing was as that but it really was looking like "all the best of its time were gone" and kinda "fubar" as some people would say and cause the location ( had to jump across other junk and maybe fight some rats to reach it ) was a bit difficult to look at it better.

Until a day moved by "deep compassion" is "I have to see it" and I manage to open it, I tought it was one of those ( so much the labelling and all was gone ) "super old maybe 8080 based black and white hw thingies" but it was puzzling me a thing was readeable on the cabinet saying "red and blue car races .. " thinking "well .. it must be something with colours then, maybe it's not SO old as I think is " ..

When I finally manage to open it, I got quite shocked at what I saw, a quite big quite modern board well done really full of chips and then I see a too famous name in a corner .. "Atari" ..

Turns out that was "Championship Sprint" and that board is an "Atari System II", initially we were thinking it was an "Atari System I", at this point "well maybe it can be fixed and put it back to work" so I searched for some docs and then .. turns out .. "what the heck is that CPU I never heard of ?" .. "It's a T-11" .. "T-11 ? .. what is it ?" ..

"Oh .. my .. it's a PDP-11 core !" :eek:

The boards has quite some damage I am still figuring out a way to carefully fix them, but the CPU has some signs of wear but "the gold kept it safe" and at this point it came into my mind the "I *MUST* make this CPU 'do something' and see if I can make 'my small PDP running something' ".

And this is how it started ...

It's not that I want to rebuild a full PDP .. but if I can put back "something to live" with that CPU this would be like "YEAH" and if one day I manage to connect my ENC28J60 Eth based interface to it and really send an email that would be "golden day of success" :D

Anyway, in all this process so far the best thing I could say is :

- I've seen/learnt things I never tought I would have had (*)
- I met some fantastic people
- I can certainly say I will never run out of things to do in my time
- It's lot of fun

And so that's that story so far, later on I'll try to post/put up something about the progress of the actual "T-11 project" but I tought that a bit of "introduction" about it was necessary.