You want to play Adventure, but don’t know how to turn on the PDP-11? These instructions are for booting our dual rack machine from its RL01 drives, although booting the single cabinet machine from the RK05 is very similar.
How to boot a PDP-11. Yes.
I always thought these old machines ran on punch cards. Guess that shows you how much I Know
This would have been more useful if it was walking us through the emulator. Is there even an emulator?
Yup.
http://simh.trailing-edge.com/ is one. It emulates a number of systems.
I don’t think emulators are that interesting, and they’re not even visually impressive. 🙂
Honestly: It’s no big deal to run decades old software on today’s laptops, but in my opinion, it’s not that much fun, and primarily it’s about fun when running old software. If you can see the whole real machinery working, feel the keys of a real terminal or a teletype, put your fingers on a real front panel of a big computer, the whole sensory perception is much more intense than what you get when you sit infront of your shiny MacBook Air, your finger on the trackpad, listening to music on your headphones. and everything works out of the box. You can learn so much more when you can get the chance to work with real historic hardware, running historic software. You hear the computer, you see parts move, blinkenlights, and it’s the original feeling that those people did experience who considered this technology their impressive working tools. They did master those tools easily on a professional level, while you have problems finding the power switch.
Why can I make such kind of claim? Because I’m living in a computer museum. The article inspires me to reactivate my original DEC vt101 terminal and do something stupid (but entertaining and educating) with it… 🙂
Yes, SimH should be able to run RT-11. It can be used to run other PDP and VAX operating systems, too.
Why can I make such kind of claim? Because I’m living in a computer museum. The article inspires me to reactivate my original DEC vt101 terminal and do something stupid (but entertaining and educating) with it… 🙂
Is there even an emulator?
Yes, SimH should be able to run RT-11. It can be used to run other PDP and VAX operating systems, too.
There are a lot of us “living computer museums” still around, and still programming. The PDP-11/04 was towards the middle of the PDP-11 lifecycle, I used to deal with 11/20s when they were still state of the art. No fancy keypad console, if the paper tape boot loader was corrupt in core memory, it had to be toggled in through the front panel switches in binary.
Oddly enough, the originator of SimH (Bob Supnik) was my first boss some 42 years ago. Back then, one of the things I worked on was MIMIC, the distant ancestor of SimH. MIMIC was a PDP-10 program that emulated PDP-8s, 11s, DG Novas, and several other long forgotten processors, and included a multi-target macro assembler, linker, and debugger. It greatly simplified development of complex minicomputer applications, particularly useful in the days when most of the systems we developed for lacked disk drives. And, RT-11 was a toy, those of us with real work to do used RSX-11A 8^)
Edited 2014-08-19 01:43 UTC
There is so much truth to this.
On the one hand, I never “ran a PDP”, but I did use one for several years in college, a PDP 11/70 running RSTS/E. We had Basic Plus, a C compiler, Fortran, MACRO-11, and Pascal.
My sole experience with it was through the computer labs via 1200 baud terminals. I knew it existed, you could see it through window of the main computer center (it was shoved in a corner, while the vast majority of the room was consumed by the CDC Cyber, with its huge cabinets, monster disk packs, and the band printer that could consume a box of green bar faster than you can hit the stop button).
So, you’d think that if I fired up an emulator, that if I got back to that friendly ‘Ready’ prompt, and a blinking cursor, that I’d be happy.
But, it’s not the same.
Maybe tinkering with the hardware and getting it to work without blowing the panel in your house is interesting. But just having the prompt, that blinking cursor relentlessly asking you “what now?”.
Well, it’s just not interesting.
The reason, for me, that it’s not interesting, is because you’re not in the time. Sure, we can look at it, marvel SYS this and $ that. We can ponder the primitive nature of the tools (TECO w/VTEDIT?? No, sorry, it’s not missed). We can point and show Kids Today(tm) how awful it was back when we only had 0’s, and not 1’s.
But a computer without purpose is a room heater.
As a developer, I help the computer bring value. Back in the day, working on the PDP, we wrote programs because that’s what we had. We didn’t have our own computer, or if we did, we couldn’t share it with anyone easily. On the PDP, we could.
My friend and I kept struggling to write a Rogue clone. We ran in to memory limits with Basic, rewrote it in Pascal, and ran in to them again. For development, we would consume three terminals in the lab, one with the editor open, one building the code, one running it. We were privileged to have a source file big enough that TECO would alert us “Loading file slowly…”, and we had to page chunks of it in manually. That’s why we never exited. That file was 70 blocks, or 35K. We were exploring overlays when we gave up (anyone else remember overlays?).
But it was what you had, the tools you had, the limitations of the system at hand. And we were learning. We didn’t even know Pascal, for example. You were in the time with state of the art hardware. Fresh and new, pushing boundaries.
Similarly, a couple years ago, I thought I wanted to build a computer. You know, old school. 6502 CPU, ram chips, etc. Put a floppy disk on it. But then I thought “What would I do with it?” How do I not make it a room heater.
And then you look around at getting the parts. Hmm, floppy disk needs a floppy controller. And how would I even create a floppy today? Oh, you can just use a flash card, and here’s the glue logic for that, but “what you should do is use a FPGA for the glue logic, this guy will sell you one for $5”.
Pretty soon you realize that you don’t need to build this thing at all. You can get a $10 micro controller, all on a chip, with a breakout board. Even more amusing, you can get one with a 6502 or Z80 simulator built in to it! “So, it’s just like the real thing.”
At this point, I’m seriously in the “what’s the point” of this exercise. What IS a computer any more anyway? When you have a half dozen ssh terminals logged in to “the cloud” on virtualized machines over virtual networks. Does computer really have identity any more? At the individual level? Computers are beyond commodity today. I imagine my wireless mouse has more computing power than the micro computers I cut my teeth on.
I ended up writing a 6502 simulator. Got a FIG-Forth running on it, wrote the simulator, wrote my own assembler.
That scratched the itch.
But eventually, I got the Forth up and running, got it debugged, got a disk block interface going, got the OK prompt, and then…that endlessly blinking cursor. “Now what?”
Now what indeed.
Back to work.
whartung,
Your post is a very interesting read.
Old technology can be highly appealing on some levels. For me, I like to visualizing how I would have done things back then. So many things I would have liked to try in the past, yet I know that it serves no purpose today. It feels so empty and unrewarding to do it now.
Skills that used to be critical have been completely abandoned. Software optimization has been neglected even to the detriment of modern software. I see lots of software I know I could do a better job building, and it’s tempting to blame bad coders for it. But at the same time my first hand professional experience is that companies care very little about quality and efficiency.
BTW borland pascal supported overlays in a fairly strait forward way and handled things behind the scenes, although this was probably well after you were tinkering with overlays.
> Does computer really have identity any more? At the individual level?
Servers have a lot more individuality and quirks than generic macbook clone #489227 or beige/black tower n+1. They have different out of band management, different form factors and board layouts, RAID cards, more NIC variety, and so on. This is diminished by the fact that companies buy them by the dozen.
An OLED display is arguably just a panel of small blinkenlights!
(too bad the only OLED-equipped device I have, Sansa Clip Zip, cannot run Game Boy or ZX Spectrum emulators from Rockbox…)
Edited 2014-08-21 23:52 UTC
Punched cards have been an important medium for input and output in the mainframe world, led by IBM. Even today’s terminology uses words like “job decks” or “DD card”. And it’s not that the “80 column default” comes out of nowhere. 🙂
On minicomputers like the PDP, punched tape has been preferred.
Both media types were later on replaced by magnetic tape and removable hard disks, as you can see in the article.
My Altair 8800 didn’t have a boot ROM. You had to toggle the boot loader in using binary switches on the front panel. Then it would boot off from cassette tape at 1200 baud.
I have a PDP-11/83. Yes to some purists it is not a real one. I cut my programming teeth on an 11/40 circa 1974/75. 56Kb Ram and a single RK05 Drive (1.2Mb).
I later went on to spend 20 years working for DEC.
The PDP-11 and the later VAXen were really able to be abused.
One 11/45 I worked on had two Unibus repeaters. We needed that simply because of all the I/O kit we had attached to it. Running RSX-11D we could run a real time simulation of an Aircraft in flight and still have 40% of the CPU free for other things like F4P compilations. All done with a clock speed in the KHz rather than the GHz.
sometimes I wonder where all that CPU speed went when my modern PC grinds to a halt so easily.
Networking, preemptive multitasking, memory protection, security improvements, and the tower of babel of abstractions that is a web browser and everything needed to run it. You can also run much better flight sims these days.
We don’t have a PDP-11, but we need help with an IBM System/38!
Edit: we also have a System/36.
Edited 2014-08-19 06:37 UTC
I remember doing these things, but we had diskpacks you needed to scew in with the handle. These look so “modern”.
What kind of a S36 do you have?
This one:
http://www.compvter.it/index.php/IBM_5360-System-36
Yeah. The RP04/05/06 drives (256Mb) could be made to dance over the floor when the think was put into diagnostic ‘full seek’ testing.
These were mostly re-badged CDC drives but with either a Unibus or Massbus interface.
An S/36? Wow, last time I saw one of those was 16 years ago when I was still at DHL. I liked how the disk drive (or pack or whatever) looked like some kind of farming implement.
Given the issues with head parking etc, i take it a power failure during use would be a very bad event…
The RK05 had a ni-cad battery for head retract, even on power failure.
But as we all know, ni-cad lifetime can vary depending on how it is maintained.
I seem to remember that there was an interlock that prevented the disk from being removed if the heads weren’t retracted first…
Especially on the RL01/RL02 line.
The last time I had to boot a PDP-11 I had to enter the boot loader into core from the front panel toggle switches in octal.
Perhaps using the Ersatz-11 PDP-11 Emulation System (http://www.dbit.com/) might be an option to run Adventure without the noise or electrical drain of the PDP-11 itself.
Edited 2014-08-19 17:22 UTC
We were still using 3 dual-cabinet PDP-11/34a systems to do system level test at a large telco when I was there – this was 1998? I think. They ran Unix System III (I think) and everything was sent to a DecWriter III. No one knew how to copy disk packs (hint: dd!)
At the very end, one of the machines quit working properly. We attempted to get what was left of Digital to migrate them over to a modern solution, as they claimed it was possible. They came in, looked around, never called back, and that part of their webpage was gone in short order.
I did some troubleshooting, found it was the second processor core, there wasn’t much we could do about it, and we used magic to work around the borked core.
When the equipment and test process was transferred to a satellite company, they found someone to convert the PDP to a PC. This solution consisted of a special interface card that plugged into the unibus in place of CPU core 0. Well, machine with the broken core didn’t work. Company that installed the conversion couldn’t understand why not. I asked the engineer in charge if he understood that the PC based solution only replaced the first processor core and drives, and that core 1 was still bad. Uh…what? It has 2 CPUs?
Yeah. Those were the days. I loved those machines. I’m guessing I am one of the few (at the time) 20-somethings that got to run PDP 11s on a daily basis.
Try original Tetris. Ran on Elektronika-60 and DVK which is essentially an 11/02 clone plus a bit. I’ve had it running off 11/23Plus and 11/83 (so probably other hardware without issue) using Russian char set via gnome term via serial and a tip session.
RT-11 here: http://pdp-11.org.ru/files.pl
Tetris here: http://pdp-11.org.ru/~form/rtgames/
Looks like it works in simh also for those without hardware.
Fun and bath-tub-safe for kids of all ages!
Also, “second original” Tetris for… PC (yep): http://vadim.oversigma.com/Tetris.htm
(ahh, must get new AA batteries for my Game Boy Advance running Tetris DX…
…BTW, Game Boy version of Tetris is the favourite of its creator: http://en.wikipedia.org/wiki/Tetris_(Game_Boy)#Reception )