I just found this in my refers. My first thought was that it was referer spam, and then I thought maybe it was a search engine.

Actually it's some sort of aggregation site, kind of, and specifically it's a post by someone who knew me in college.

Ah, the PDP-12! Them was the good old days. 4096 12-bit words of core! Linc-tapes! A graphics display! And no hard disc! And the best part of all was that we could use it as much as we wanted, for free.

I did do a version of Pong for it, but I was more proud of my space war program. Our PDP-12 also had 16 analog inputs and 8 of those were hooked to pots. Each player could use two of the pots to control a space ship respectively representing X and Y acceleration. There were 6 rocker switches on the console, and each player got three of them.

One player ran a Klingon ship and the other ran the Enterprise. One rocker switch fired the phasers, another fired a photon torpedo, and the third dropped a mine, which would activate after two seconds. Once activated it would destroy anything that came within range, friend or foe. (Which meant that if you were moving too slowly when you laid a mine field, you could be destroyed by it.)

A lot of people spent a lot of time playing that game, and I learned a lot by writing it. Thinking back on it, I'm still astounded how much I managed to fit into just 4K.

I wonder who made that post? After 35 years, I wonder if I'd even remember the name if I did see it? (Probably not; my memory has been going bad recently.)

UPDATE: I also wrote a cut-down version of TECO for the 12 which I called PIE ("Programmable Interactive Editor"). After it became mature, one of the upper classmen suggested I show it to a professor. After he saw it he gave me 3 hours of credit for it. Which was pretty cool.

Thinking back on it, I'll be damned if I know how I fit all that into 4K.

Posted by: Steven Den Beste in Site Stuff at 03:49 PM | Comments (13) | Add Comment
Post contains 363 words, total size 2 kb.

1 Was that 4k of program-size, or 4k of system memory for editor plus document?

Posted by: karrde at March 02, 2009 07:07 PM (aF0WK)

2 Never laid eyes on the PDP-12, but it makes me think of ALGOL for some damn reason?? Brain fart I guess.

Posted by: toadold at March 02, 2009 08:31 PM (zcbXo)

3 I'm quite fortunate to be born late enough to start in the PDP-11 age.

Posted by: Pete Zaitcev at March 02, 2009 09:38 PM (/ppBw)

4 That was 4K of everything. The editor obviously couldn't hold it all at once, and it worked by swapping in and out of the tape.

Posted by: Steven Den Beste at March 02, 2009 10:02 PM (+rSRq)

5 By the way, y'all do know what "core" is, don't you? I wasn't speaking figuratively; the 12 used real core memory.

Posted by: Steven Den Beste at March 02, 2009 10:09 PM (+rSRq)

6 When I started at UNSW, one of our PDP-11/70's still had core memory.  2 megabytes of it.  It must have had most of a rack just stuffed with memory boards; I'm amazed it worked at all.

Posted by: Pixy Misa at March 03, 2009 01:31 AM (PiXy!)

7 I started with a Soviet clone of 11/20 (approximately). It had 32 or 64KB of core as shipped, but it was quickly swapped out with DRAM. I spent quite some time cutting out and replacing bad DRAM chips in it. Zelenograd silicon was always like that.

In college, we had a Hungarian copy of Bull Mitra-15, which had 64KB of core. It supported stop and restart over the power failure by saving registers. In contrast, PDP-11 clones typically didn't have the right power-fail interrupts. Core rings on the Mitra were about 1.5mm wide -- much smaller than Soviet core, and the quality was excellent.

Posted by: Pete Zaitcev at March 03, 2009 07:31 AM (/ppBw)

8

That's right...the "core" memory was a set of small ferro-magnetic metal cores on a wire grid. Kind of like this, right?

Posted by: karrde at March 03, 2009 09:31 AM (EaCUv)

9 That's the stuff.  Tell kids today that we used to make memory out of tiny ferrite donuts strung onto a wire mesh they and they won't believe you.

Not sure I do, for that matter.

Posted by: Pixy Misa at March 03, 2009 06:32 PM (PiXy!)

10

That's the stuff.  Tell kids today that we used to make memory out of tiny ferrite donuts strung onto a wire mesh they and they won't believe you.

Was that back when a computer network really was just "a bunch of tubes"?  

You all are making me feel like a youngster - I can remember seeing punch cards when I was a kid, and in the Air Force I saw a punch card reader in the corner of a storage room once.  I can understand memory limits - I started programming on a HP41CV calculator and my brother in-law's TRS-80.  But having to program around winding and rewinding tapes for storage?  I just can't grasp that...

Posted by: Siergen at March 03, 2009 07:30 PM (BIB5p)

11 Hmm.  The US Army was still using punched cards for logistical information as late as 1990.  (That's the last time that I remember seeing it.)

Posted by: Mark A. Flacy at March 03, 2009 08:46 PM (i9fDQ)

12 This reminds me a propaganda book "Frontine of Secret War" that breathlessly proclaimed how "Pentagon keeps an archive of more than a million of perforated cards!"  It also had pictures of all the cool stuff Gary Powers carried with him, like a silent pistol. The book was published in 1970 or about that.

Posted by: Pete Zaitcev at March 03, 2009 09:03 PM (/ppBw)

13

I programmed using punch cards when I was in college. This was 1972-1975, and the main computer for student class usage was a CDC-3300. We submitted our programs as punch-card decks and got our result as a printout. Turnaround could be as good as 15 minutes (sometimes even less!) or much much worse, as a function of how many people were doing how much.

Gad, that was terrible!

About the time I started going there, the school was proud to acquire a CDC-6400 which they put in the same computer center. But that was for research; we students didn't get to use it. (I think the Oceanography department was a big source of funds for that acquisition.)

Posted by: Steven Den Beste at March 03, 2009 10:02 PM (+rSRq)

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