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Vercus
July 9th, 2009, 09:19 AM
Hello Everyone,
I am new to the forum, but not too computers. I am 27, so I was getting started in the 80's. My first computing experience was with my Dad's Apple IIc, then later with my own DOS and Win 3.1 based PC's.

I was given a DEC VT-102 terminal in perfect working order, however I don't know how to use it. I don't have a mainframe for it, or any other DEC hardware for that matter, just a modern Win XP computer, and a few old Macs. My question is this: what do I need to get to be able to use the terminal? I love the old DEC stuff, and would really like to get a system setup. From what I have researched so far, it seems that a VAX 11/750 is a good one to use with it? However, I don't have much money, and as much as I would LOVE to get a mainframe / terminal / disk drive / tape system setup, I just don't think I could afford it.

I am eager to get it setup, as I have always liked the 80's DOS / disk based systems. The idea of having my own mainframe system with local terminal and disk storage is definitely appealing, but I don't know how to go about it, or how much it would cost.

What recommendations would you have to get up and running? Do you know of any good places to go to get some vintage computer equipment without spending a lot of money?

Thanks in advance for your help!
-Jon

RetroHacker_
July 9th, 2009, 10:11 AM
The VT102 is pretty much the same as it's predecessor, the VT100, I believe they just integrated the AVO onboard or something.

You don't _need_ a vintage system to be able to use a dumb terminal. I use mostly Linux at home, and it's trivial to connect a VT100 to a modern Linux (or any Unix, for the most part) box and use it as a terminal. I actually have a VT100 in active use, connected to a serial port on an AMD Athlon based PC/clone.

All you need to do is make up (or find) an RS-232 null modem cable, and hook it up, and configure the OS to talk to it. I do believe that there is something available for Windows systems that allows a command prompt to be used from a dumb terminal, but since I don't use Windows, I have not messed with it.

As for the operation of the terminal itself, if you press the Setup key, you can go into the setup and change the options. It first puts you in Setup A, you need to press the Setup A/B key (5, I believe, it's marked) to enter Setup B. From there you can change parameters. This is done with virtual dip switches - a row of digits along the bottom of the screen, you have to select one with the arrow keys, and then press the marked key to toggle it. What the settings do is described in the manual (available from vt100.net), or sometimes on a sticker on the bottom of the keyboard.

From Setup mode, you can also press the Local key on the keyboard, and then exit Setup mode, so then things typed on the keyboard just get displayed on the screen. Good for testing.

These terminals were commonly used on the later DEC PDP-11 systems and earlier Vaxen. They kinda became a de-facto standard, and got used on many other systems. A good system to look for would probably be a DEC PDP-11/73, a pretty common Q-bus based 11. It's pretty small and easy to work with. The most common disk controller board, the RQDX3, talks to standard 5 1/4" floppy drives as well as common MFM hard drives, the ubiquitous ST-225 being supported. A MicroVax II is also a good choice, with many compatible parts with the 11/73.

Also note, the 'cat' command on certain versions of Linux supports the VT100 a little bit TOO well. Be careful with the option strings:
http://i250.photobucket.com/albums/gg280/RetroHacker/term_cat.jpg

-Ian

cosam
July 9th, 2009, 12:52 PM
So you've got a steering wheel, now you just need the car to go with it? ;-)

As Ian pointed out, you don't need anything vintage (or even DEC) to use the terminal, but I get the impression you'd like to run some big iron. What you get is often determined more by how much space you have than how much cash. A VAX 11/750, to use your example, is the size of a small but pretty wide/deep refrigerator. Add a tape drive: figure another fridge next to that. Same goes for a rack for contemporary disk drives. If you have the space, I certainly wouldn't discourage you from taking that route - there's nothing quite like working on CPUs build out of several boards' worth of discrete chips!

If space is more limited, a Qbus PDP-11 or smaller VAX might be right up your alley. They range from the size of a large PC case up to a short fridge-sized rack or two depending on the model and which peripherals you hook up. The electronics are much more integrated, but they're still fun to tinker with and have many features recognisable to those used to more modern hardware. You still get to play with big disks and tapes if you want to, or you can opt for 5.25" form factor storage devices.

Actually getting hold of a system needn't be expensive. If you're in the right place at the right time, you can pick a lot of gear up for very little - or even free - if you're prepared to haul it away. Try to get in touch with local people with similar interests and do a bit of detective work on local scrappers/recyclers and companies/organisations who might have old computer stuff. Eventually something will turn up.

barythrin
July 9th, 2009, 01:36 PM
Besides old agencies and companies, ham radio conventions, sometimes craigslist or freecycle can be good hits. Asking around here, or searching auction sites themselves or via google (search string is whatever word then add site:whateversite.com to only search that site). I do that with craigslist.org on occasion when I'm bored.

Chuck(G)
July 9th, 2009, 02:09 PM
Wasn't there a field-installable option to turn a VT100 into a VT180 (Robin)? That would make this VT102 a complete system...

Lou - N2MIY
July 9th, 2009, 03:08 PM
The VT180 Robin option goes in a VT100, not a VT102. The VT102 was the cost-reduced version of the VT100. You can see the inside of my Robin here:http://www.vintage-computer.com/vcforum/album.php?albumid=2&pictureid=63

I second all of the votes for Qbus 11s as being a great companion for the VT100!

As for finding a system, Lallander found an 11/23 system with dec RL02 disk drives for $200 a few months back. That's some pretty good early 80's iron.

Jon, where in PA are you (closer to Philly or Pittsburgh?)

Lou

Vercus
July 9th, 2009, 03:28 PM
That sounds like a good deal. I don't really have too many contacts in the computer industry, let alone the vintage one. I tried checking craigslist within about a 2 hour range, and wasn't surprised to not find anything. Certainly if it does work out, it will take time. In the meantime, I'm grateful to learn about appropriate equipment for my situation. From what I'm hearing, it's sounding like the PDP-11 series is a good one to go with?

I have two questions concerning this equipment in general:

1. Can they be reconfigured into a different cabinet if the existing one wouldn't be friendly to my room dimensions? I would have a dedicated room for this system..(yay!) and while it has plenty of width (about 20 feet) the ceiling is not very high. I'm guessing around 6-7 feet (I'll measure when I get home to verify).

2. What kind of electrical service would this stuff need? I just have standard house voltage- 120V. I have read that some of this stuff needs 208. Needless to say, that would be a problem for me. This room is on a separate breaker fortunately. Actually it's a separate electrical service altogether from the rest of the house.

Any thoughts?

-Jon

Vercus
July 9th, 2009, 03:32 PM
Hey Lou,
I forgot to mention- I live in Shawnee on Delaware, which is in the poconos, in the northeast section of Pennsylvania, close to the New Jersey border. I'm about 2 hours north of Philadelphia.

-Jon

Lou - N2MIY
July 9th, 2009, 03:58 PM
Jon,

IMHO, there are a number of reasons that an 11 makes a good hobby machine. I'd say that the most important reason is the availability of documentation, then second the availability of software, then third the availability of hardware.

The system can take up as much or as little space as you want it to. There was a VT103 terminal that is the same size as your VT102 and had a qbus backplane in it, enough room for an 11/73 processor, some memory, and a disk controller. At the opposite end of the spectrum, you can have a lineup of 6' tall 19" racks with your favorite TU80 tape drive and other really big iron. For the biggest iron, it's helpful to not need 3 phase 480V power - you will be OK with standard 120V home power. In my case, there is only so much the wife will put up with, so the little 4' high 19" racks work out well for the garage, and the little deskside cases like the micro 11/23 and micro 11/73 are good for inside the house. Everything can be reconfigured, especially in 19" racks.

Hardware documentation is really good. Dec wrote really good manuals and the field maintenance print sets / tech manuals for most things are indexed online at MANX (http://vt100.net/manx/). You have plenty of OS's to choose from, available online (RT11, RSX, NetBSD, Ultrix-11,....) If you want to get crazy and set up a bank of terminals and run a multi-user OS, go for RSX. Spare boards are frequently on ebay and systems turn up on craigslist every few months.

You're not too far from me, so I'll keep my eyes open for systems within driving distance. Keep your eyes out at the surplus operation of your local university too. Get the word out at those places what you're looking for and make sure they remember you.


Lou

RetroHacker_
July 10th, 2009, 07:11 AM
Just to add a word of warning. Be careful collecing big iron. It can get out of hand. I know from first-hand experience. It starts off innocently enough, with a small PDP-11/73 or MicroVax. Then you wind up with a washing machine sized mini or two, and a couple racks. Then, before you know it, you've got a basement full of equipment, very little of which you can lift yourself, and some of which you cannot even power.

I currently have two computers in my basement that require three phase power, and I don't have three phase service. I own single hard drives that I cannot lift. I can dim lights *on another circuit* when I power up a particular machine. I've got several friends that learned the hard way not to come over to "help me move something".

All of this joking around aside, welcome to the exciting world of minicomputers! There is fun to be had around every corner. Just keep looking, sooner or later something will find you. And when it does, we'll be here to help you get it working.

-Ian

barythrin
July 10th, 2009, 08:51 AM
lol Ian, I was gonna warn him the same as well but sounds like you have heavier stuff than I do. I have a few servers that aren't recommended for a one man lift and have wheels and odd power requirements.

Either way, don't let it spook ya from the dream. The catch and lesson most of us end up with (hard to pass up though when first starting) is the take anything syndrome. Anything cheap/affordable or that someone gives you that you think is cool but obviously would cost them to dispose of and eventually you'll end up with no room to work with and piles of stuff laying around. It's cool at first, until your workbench never has any room for work.

One small thing to keep in mind if you did go that multiple rack method (besides your wonderfully heated but radiated room) is the weight. It's not something I think of very often myself and I probably have a dangerous amount of weight in one room upstairs but most of my stuff is on the first floor. It may not be something you have to worry about but just as a warning, if you end up with 3 1200lb racks side by side in your appt, you may want to think about moving to the first floor before your equipment does.

tradde
July 10th, 2009, 10:02 AM
If I had an extra pdp-11 I'd offer it to you. I collect mostly pdp-8 stuff. My only 11
right now is a pdp-11/84. If I run across anything I will post you a message. If you
are patient something will come your way.
Tim R

Vercus
July 10th, 2009, 12:20 PM
Hello again,
Thanks for advice. I can see how it could get out of hand. I measured the room, and it's not quite as big as I thought:
17 feet wide, 10 feet deep, ceiling slopes from 8 feet to 5 feet.
Now of course, I can't dedicate that whole room to vintage computer equipment, and don't really want to. At the same time, I want to have something solid enough that I feel like I'm working on a real system. I'd say if I could get everything in 2 or 3 19" racks, that would be good.

One concern I do have is the weight, as mentioned by another member. This would be on the second floor of a 100+ year old apartment. I would definitely prefer that the equipment *stay* on the floor it was installed in! I see DEC made some smaller tape units, like the DECTape, which was supposed to be pretty reliable and good as far as dropout resistance. However, it seems to use a special tape, compared to the standard machines which use 1/2". Are there any machines that use 1/4"? I have tons of that stuff sitting around that I have no use for.

As far as time, I'm certainly patient. I have to do some clearing out of the backroom anyway. I've amassed quite a bit of stuff to clear out back there.

-Jon

Lou - N2MIY
July 10th, 2009, 04:33 PM
Jon,

Do you own this apartment? After you move it once, you're going to want that iron to stay there. It can be a big job hefting the racks up flights of stairs. When my parents moved, my 8/e was in a full height rack with a TU10 magtape drive (the rack was a proper dec H960) in their basement. It had to be gotten up one flight of interior stairs to get it out (to get it to the van to get it to my place). Everything had to come out of the rack, and it was only 400 lbs when full. The TU10 was a killer because it made the rack topheavy!!!

In undergrad, myself and three other guys carried an IBM magtape drive with two Fujitsu Eagle drives in a wide rack up four flights of stairs. That must have been ~500 lbs. We were nuts.

You're gonna need friends and beer and pizza. Even then, I think you'll want the little short 4' tall racks. They will be easier to move and be easier on your floor (in a pounds per square foot sense). You can use the top as a counter for the video terminals (and line printers if you go with LA34/38/100 that aren't floor-standing units).

Dectape drives are hard to come by and fetch $1000 on ebay, so don't get your hopes up. I've thought that maybe I could trade my KA10 console for one (with a TC08 ), but that would probably be a stretch. Best you satisfy your tape jones with a regular 9-track magtape drive.

Lou

Vercus
July 10th, 2009, 08:00 PM
Hey Lou,
Thanks for the helpful information! I am renting the apartment. Fortunately, there is only 4 or 5 stairs, as it is on a hill. I like the idea of being able to put the terminal on top of the rack. As far as tape, I am perfectly fine with a 9 track unit. I would prefer it actually. Aesthetically, I really like the vertical ones where you can see the tape doing it's thing. Especially great with those random unexpected darts from one section to another. I'm sure ultimately it will come down to what I can find / afford. Any recommendations as what tape models to look for / avoid?
-Jon

tradde
July 11th, 2009, 05:53 AM
I have a short rack (maybe 2) if you are interested. I have the side panels too and maybe
even the rear door for one. I'd worry about getting the processor and then depending on
what you get for that getting a tape drive that goes well with the system. TK50's seem
common with the later 11s. I don't think you see many older type tape drives for these
pdp-11s much these days. I live down near Philadelphia, so am not too far (a few hours
at most).
Tim R

Vercus
July 11th, 2009, 07:40 AM
Hey Tim,
What would you be looking to get for the racks?
Thanks,
-Jon

tradde
July 11th, 2009, 07:54 AM
Norhing really if you were to come get them. I need to get stuff out of my basement
and the more you take the less I have to figure out what to do with. Plus you could
see my collection of stuff (pdp-8e, pdp-8i, and 11/84). I was going to post the pic
of the 4 rack 8i here, but it's too big for a quick download. :)

pontus
July 11th, 2009, 12:29 PM
Jon,

Dectape drives are hard to come by and fetch $1000 on ebay, so don't get your hopes up. I've thought that maybe I could trade my KA10 console for one (with a TC08 ), but that would probably be a stretch. Best you satisfy your tape jones with a regular 9-track magtape drive.

Lou

Ooh, now I feel like searching for dectapes and controllers :) A KA10 Console looks dreamy!

Perhaps I'll find something, just got a load of unexpected goodies. A thread will be made next week :) Just let me say that moving a 11/750 up one flight of stair is _hard_ work.

tradde
July 11th, 2009, 12:59 PM
Ooh, now I feel like searching for dectapes and controllers :) A KA10 Console looks dreamy!

Perhaps I'll find something, just got a load of unexpected goodies. A thread will be made next week :) Just let me say that moving a 11/750 up one flight of stair is _hard_ work.

A KA-10 console IS dreamy. I had access to a KA-10 while I was at Penn State. It was
a beautiful machine, but huge. It was connected to an analog computer too. I often have
ideas of emulating a KA-10 in an FPGA and having a front panel made for it. But then I wake up and think of how much a front panel would cost to build (with the switches and lights).
Heck just the bare front panel wouldn't be cheap to have made.

Vercus
July 11th, 2009, 05:51 PM
Tim,
I'm working in Lansdale Monday through Thursday this week. Lansdale is about 30 miles north of Philadelphia, just off 476. So, depending on schedule, I might be able to swing by after work on Thursday, if that works for you. Are these DEC racks, or just standard 19" equipment racks?

I would love to see your PDP setup! Sounds like a great opportunity to see this stuff in action. I hope you don't mind if I ask you lots of questions! Feel free to shoot me a PM anytime, and maybe we can set something up.

The weather is getting bad tonight, so I'm gonna shut the server down. So, no more internet for me tonight, but I'll be able to check my e-mail again tomorrow, or maybe later tonight if things clear up.

Take care,
-Jon

EvanK
July 13th, 2009, 01:02 PM
I would love to see your PDP setup!

Or you could visit the Jersey shore (the REAL one, not the town of "Jersey Shore, Pa." which I'm told exists) ..... we have a PDP-8 .... 4K of 12-bit words of core memory. Fun!!

ahm
July 13th, 2009, 02:56 PM
not the town of "Jersey Shore, Pa." which I'm told exists
Easy enough to check... http://maps.google.com/maps?q=jersey+shore,+pa

pontus
July 14th, 2009, 06:08 AM
Or you could visit the Jersey shore (the REAL one, not the town of "Jersey Shore, Pa." which I'm told exists) ..... we have a PDP-8 .... 4K of 12-bit words of core memory. Fun!!

Is it functional?

EvanK
July 14th, 2009, 09:48 AM
We haven't tested it. So far all we only did an initial cleaning of the top layer of dirt (and who knows what else - it was literally inside a barn). Since then it's been on display as-is. We're going to look into a serious restoration later this year or early next year. One of members is qualified and interested in this project.

Ours is #1,158 of 1,500. Here is a not-so-good picture, without the side covers. Previous owner built the wooden platform.

http://snarc.net/pdp-8.jpg

tradde
July 14th, 2009, 02:59 PM
Both of mine are. functional. I wish the 8i had some working storage and more memory.
It would be much more fun to toy around with running OS/8 or something similar on it.
I'd like to see it run Adventure. I can run that on my 8e. But the front panel of an
8e just isn't as nice as the 8i. Or the straight 8. I learned on an 8i and therefore never
felt drawn to a straight 8. Of course if someone offered me one I would of course take it. :)
But we all know that won't happen.

Lou - N2MIY
July 14th, 2009, 03:45 PM
Well, I always looked at those non-Omnibus 8s and thought the front panel looked too busy. The 8/e seems just right. Does one really need to be able to see the contents of the AC and MQ and the bus at the same time?

Tim, you should build a solid state memory for that 8/I. Two 62256s and you have 32kW of memory. You could fit the whole thing on one dual height card.

I am curious what makes someone "qualified" to work on a straight-8. I suppose they should at least be as old as the machine. At least I am then "qualified" to work on my 8/e :).

Lou

tradde
July 14th, 2009, 04:31 PM
Well, I always looked at those non-Omnibus 8s and thought the front panel looked too busy. The 8/e seems just right. Does one really need to be able to see the contents of the AC and MQ and the bus at the same time?

Tim, you should build a solid state memory for that 8/I. Two 62256s and you have 32kW of memory. You could fit the whole thing on one dual height card.

I am curious what makes someone "qualified" to work on a straight-8. I suppose they should at least be as old as the machine. At least I am then "qualified" to work on my 8/e :).

Lou

Solid state just isn't the same as core. And these machines deserve core memory. Yes,
I like seeing all the registers all the time. The 8e just seems annoying if I am looking at
memory and then want to see the AC value I have to turn a knob. Yeah, I know it helped
reduce to cost of the front panel and saved lights. I have a memory expansion unit (Fabritek 24k) but it blew the -15v transformer and I have not gotten back to figuring the
best way to fix it. And also making sure what caused the short is fixed too.

Did he mean qualified to work on a straight 8 only? Or just the older model 8s in general?
I know the 8i is much easier to work on than the 8e since each flip chip is pretty limited
on what it does and has on it. If you have to be at least as old as the machine then
I am over qualified.

billdeg
July 15th, 2009, 04:25 AM
MARCH museum's straight-8 PDP/8 has history behind it, aside from being an original PDP 8 machine.

Comparing the first PDP8 with later models is the same as comparing a 1957 Chevrolet Corvette with a 1979 model, they're both Corvette's but...

The following link contains photos of MidAtlantic-area computing from the 60's. The PDP8 computer depicted in these slides and owned by Claude Kagan was moved from Claude's barn to the MARCH museum:
http://www.tcf-nj.org/ACGNJ%20history_1.wmv

All of the later PDP 8 models are smaller, more efficient versions of the original straight-8.

Here are some pictures I took of this same computer from the slide show, 40 years later, the day it was picked up from the barn at Claude's home, and brought to the Trenton Computer Festival for display. Later that weekend the system was moved to MARCH's museum:
http://vintagecomputer.net/tcf_2008/
NOTE: The link contains pics of an Intel dev computer, ASR 33, and a Calcomp plotter too also donated by Claude. Some people pics too (Evan)...

My favorite (now that's a card cage):
http://vintagecomputer.net/tcf_2008/digital_pdp8_sn1158_front_full-c.JPG

Claude Kagan
http://vintagecomputer.net/tcf_2008/Andy_Meyer-Claude_Kagan-at-TCF2008.JPG



Bill

Vercus
July 16th, 2009, 08:28 PM
Well, thanks to the generosity of tradde, I now have an RL02, and a disk pack. I haven't tested it out yet of course, since I don't have a CPU for it, but nevertheless, it's good to have. I wasn't able to take the rack yet, as we felt I should bring some stuff along to secure it before traveling. That empty rack was HEAVY! Both of us were pretty winded after hefting that thing up the stairs.
Thanks for showing me your PDP-8 setup Tim, and thanks for the drive! If you're ever looking to get rid of other DEC iron, let me know. Looking forward to seeing you again to pick up the rack.
Take care,
-Jon

VintageComputerman
July 18th, 2009, 07:16 AM
Item number: 380138438557

Winning bid: US $114.50

Vercus
July 18th, 2009, 05:07 PM
That looks like a really neat terminal. It's interesting that it's a green screen. Mine is black and white.

-Jon