Using a Tektronix storage tube terminal or emulator with the PiDP-11

[Rene Richarz]

I have been able to login with a Tektronix terminal emulator into 2.11 BSD on the PiDP-11, and have written a few small demo programs. If you want true 1970's feeling, this is it. The setup allows for several terminals to login into 2.11 BSD at the same time.

This is a graph of weather data acquired and displayed on the PiDP-11. Yesterday during the gap between 10:15 and 12:40 my cool-retro-weatherstation on the PiDP-11 did not acquire weather data from the sensor. My system was down for maintenance. It was a cloudy day with the sun shining only for a very short time.

Tektronix storage tube terminals like the 4010 played a very important role in the 1970's, when memory was still extremely expensive. In the early 1980's, there were other less expensive terminals emulating the storage tube terminals using dot matrix hardware, but did not provide the same crisp vector graphics. We used a Graphon terminal at that time to display scientific data using Unix on a PDP-11. Tektronix terminals were used in our company for CAD. On a storage tube display, you can display as many characters and vectors as you want, but the only way to erase anything is to erase the whole screen. The emulation I used mirrors this behavior. This makes it unsuitable for animations.

Details of my setup are at https://github.com/rricharz/pidp11-2.11bsd.

I would be very interested in a Tektronix graphics library for the historical Unix, and in historical programs. Is anybody aware from where these could be obtained?

[Peter Willard]

I recall, in 1978-9, that the TEK 4014 terminals on all the DEC computer driven chip testers were pretty cool. We had about 20 Tektronix stations manned 24 hours testing incoming chips.  But they suffered from a lot of phosphor related problems like severe burn-in and were actually very slow to update screens.  They looked really neat on Battlestar Galactica though (since few, at the time, recognized they were not futuristic sci-fi displays but real current day stuff).  

[Ian Schofield]

Dear All,

 I thought the 4010 was the best thing since sliced bread when we got one in 1982 attached to (yes) a PDP8/I with a DF32 disk. The screen copier was very useful as well when we could afford the paper! Emulating this on modern displays as really hard as the lines just don't look right and, getting the writing beam motion just so is tricky.

 Same problem as for the VT11 emulation. It is unfortunate that analogue devices are increasingly a thing of the past!

 In the meanwhile, https://inis.iaea.org/search/search.aspx?orig_q=RN:10467689 is a good place to start as there are quite a few TEK4010 modules out there for RT11 and up. Hopefully, the software is in some disk images somewhere.

Regards, Ian.

[Rene Richarz]

On Wednesday, March 13, 2019 at 8:19:12 AM UTC+1, Rene Richarz wrote:

I would be very interested in a Tektronix graphics library for the historical Unix, and in historical programs. Is anybody aware from where these could be obtained?

In the mean time I found a very early version of the plotlib library on the 2.11 BSD image. I made a short example if anybody is interested. Go to https://github.com/rricharz/pidp11-2.11bsd, and use the link "Doing nice vector graphics on a Tektronix 4010". At the bottom of this tutorial you can find a picture, which has been made using plotlib. The source of the C program is in the "tek" directory. As far as I understand this library is also available for Fortran programming. This library also allows linking for other graphics terminals (see "man 3 plot").

[Ian Schofield]

Dear All,

 I am sure you have all seen a real 4010 but, this video is the best I have seen: https://www.youtube.com/watch?v=IztxeoHhoyM

 Richarz; many thanks for publishing the test software as per your link.

 Having done some experimentation recently, I think that modern displays are nearly up to a reasonable emulation. Mine is 2560x1440(WQHD) ... a bit marginal. 4K should nearly be OK.

 Attached is a VC8->VR14 emulation screen grab of some old game that no one will recognise!

 For this sim, the pixels fade to black.For a storage screen, the pixels fade to the stored image brightness set by the the flood gun current.

 This screen region is refreshed at 50Hz and all the pixels are just 3x3 crosses (+) at the moment. The best pixel pattern for a single beam spot remains to be determined. Probably 3x3 gaussian.

 3072x2340 display required for this format.

 Certainly worth a try as I think we would all like a convincing 4010/4014 attached to our PiDP11s

Regards, Ian.

 

[Johnny Billquist]

On 2019-03-22 23:35, Ian Schofield wrote:
> Dear All,
>
>  I am sure you have all seen a real 4010 but, this video is the best I
> have seen: https://www.youtube.com/watch?v=IztxeoHhoyM
>  Richarz; many thanks for publishing the test software as per your link.
>  Having done some experimentation recently, I think that modern
> displays are nearly up to a reasonable emulation. Mine is

> 2560x1440(*WQHD)* ... a bit marginal. 4K should nearly be OK.

Well, you're about half the resolution, if we count discrete points.

>  Attached is a VC8->VR14 emulation screen grab of some old game that no
> one will recognise!
>  For this sim, the pixels fade to black.For a storage screen, the
> pixels fade to the stored image brightness set by the the flood gun current.

Uh... Not necessarily. With a 4010 or 4014, you can both draw permanent
things, or things that disappear. It depends on your controls. It's all
documented in the manuals, if you are curious.
The cursor was an example of something writing non-permanent.
But you could draw anything yourself as well. However, obviously, if you
wanted it to stay around you then have to redraw it all the time at a
high enough refresh rate.

>  This screen region is refreshed at 50Hz and all the pixels are just
> 3x3 crosses (+) at the moment. The best pixel pattern for a single beam
> spot remains to be determined. Probably 3x3 gaussian.
>  3072x2340 display required for this format.
>  Certainly worth a try as I think we would all like a convincing
> 4010/4014 attached to our PiDP11s

Within some limitations, xterm works just fine as well.

Johnny

--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol

[Rene Richarz]

Nice video!

Xterm is the best we have as a 4010 emulator, if you just look at the resulting drawing. But it makes no effort to emulate the actual drawing process. As far as I understand, it does not support the write through or dark mode of the 4014 (except internally for the cross hair cursor).

I had actually some thoughts on how much work it would be to write my own emulator in C, and as far as I can see emulating the 4010 even on a Raspberry Pi using a reasonable resolution screen would be feasible. I have even considered proposing a 4010 as Oscar‘s next kit :-)

But there are quite some roadblocks to overcome:

1. On a raster display, the final drawing will never be perfect. There will always be distortions due to the raster. The higher the resolution of the raster display, the better, but higher resolutions means also more resources required for the special effects.

2. Normal permanent writing, the high intensity drawing point, the dark mode crosshair cursor and the limited speed would be reasonable easy to emulate.

3. Dark mode drawing (4014 graphics code set) could be implemented, but would require a separate canvas. The intensity of each point of that canvas would have to be constantly reduced, before it is combined with the permanent canvas. Available memory and speed would be a major issue at high resolution. As an alternative, one could limit the number of vectors to be visible in dark mode, store them in a table and draw them at each refresh. I think in reality this number was also very limited on the real thing by the speed with which data was transferred to the terminal, and the time it took for any given vector to fade away.

4. The work does not make sense unless we have a sufficient number of historical programs available. At least for the historical Unix systems that I am interested this does not seem to be the case. I have written a few such graphics programs myself in the early 1980s, but sadly enough all of that work was lost after we moved to Sun workstations. In the 1980s technology advanced so fast that we just did not have time to look backwards.

Combining all these thoughts I came to the conclusion that this project would exceed the amount of work I would be willing to spend on it.

[Ian Schofield]

Dear All,

 Thanks for the above. I think Johnny's point about the limitations of xterm are relevant. The main point here is it that displays are now available that can give a better impression of the original system. In the meanwhile, we can try anti-aliasing (see attachments) but this only goes so far.

 (This is from a new simh/VT11 option in development which has the same problem.)

 So, I do appreciate that we may need to resort to 4K displays and a gaming level GPU ... increasingly becoming the norm anyway.

 Finally, in regard of software, there are many apps that will drive this terminal for which there is no end of interesting stuff. And, of course, bsd2.11 has the plot system that we can all use on our PiDP11s.

Regards, Ian.

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[Chuck McManis]

FWIW, I've got a VT340 which was the color raster graphics terminal that was DEC "standard", emulating ReGIS graphics is both possible and period appropriate for the PDP 11/70.

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[Rene Richarz]

On Saturday, March 23, 2019 at 10:36:19 PM UTC+1, Ian Schofield wrote:

I think Johnny's point about the limitations of xterm are relevant.

I agree to some degree. On the 4010 the coordinates for drawing vectors had a resolution of the coordinates of 1024x780 points. On the 4014 with the enhanced Graphics module installed the resolution of the coordinates was 4096x3071. I have no information what the internal resolution of the DAC's, the line width and the effects of the analogue hardware were.

Of course antialiasing is essential for a proper emulation. I think given the philosophy of the 1970s one should try to achieve the design goals with the minimal resources necessary. The Raspberry Pi can draw with antialiasing at a more than sufficient speed to emulate a 4010 or even 4014. See my attached youtube video: https://www.youtube.com/watch?v=BWpOrIYcTV0.

And the two screen dumps with and without antialiasing using cairo drawing:

[Rene Richarz]

I have a second short video which shows the emulation of the Tektronix 4010/4014 graphics on the Raspberry Pi including persistent mode drawing with the initial high intensity beam, and dark mode drawing with fading. I believe that this shows that it would be quite easy to write a Tektronix 4010/4014 emulator with these features.

https://youtu.be/vSZrVyzeHGM

[Rene Richarz]

On Saturday, March 23, 2019 at 11:26:20 PM UTC+1, Chuck McManis wrote:

FWIW, I've got a VT340 which was the color raster graphics terminal that was DEC "standard", emulating ReGIS graphics is both possible and period appropriate for the PDP 11/70. 

 

Yes, the VT320 family (introduced 1987 according to Wikipedia) and a large number of other B&W and color raster graphics terminals were introduced throughout the 1980's, which is of course well within the period of the PDP-11. It is definitely  an appropriate terminal to use with a PDP-11. I used a few such terminals myself and have considered rewriting my own ReGIS library. Unfortunately my original one written in the 1980s was lost. I have not looked into whether good terminal emulators with ReGIS capabilities are available for those who do not own an original one.

The Tektronix 4010 was introduced about 15 years earlier than the VT320 family, and had extremely crispy high resolution graphics which we can only start to emulate reasonably well today with the latest displays and graphics processors. In my opinion the electronics industry gave up a lot when they moved to raster displays (they also gained a lot of course). I feel it is therefore more than appropriate to show to young people what was done with more or less analogue technology almost 50 years ago. That's living history and I guess that's why there is quite some interest in these famous ancient terminals. Unfortunately there are probably not very many 4010's still running, and it would therefore be very nice to have a good emulator.

[David Richards]

Greetings,

On Sunday, 24 March 2019 20:28:35 UTC, Rene Richarz wrote:

The Tektronix 4010 was introduced about 15 years earlier than the VT320 family, and had extremely crispy high resolution graphics which we can only start to emulate reasonably well today with the latest displays and graphics processors. In my opinion the electronics industry gave up a lot when they moved to raster displays (they also gained a lot of course). I feel it is therefore more than appropriate to show to young people what was done with more or less analogue technology almost 50 years ago. That's living history and I guess that's why there is quite some interest in these famous ancient terminals. Unfortunately there are probably not very many 4010's still running, and it would therefore be very nice to have a good emulator.

There is this Tektronics  4051 in my local museum waiting to be restored, cant wait to see it working again. David.

[Rene Richarz]

I have now as a proof of concept the first version of a Tektronix 4010 emulator ready. It does emulate the bright drawing spot (even so it is less bright in the video as compared to looking at the screen directly), and has the hooks to include the dark mode.

     https://youtu.be/jMYCL1I6-IU

This is not a fake. The emulator is running on a separate Raspberry Pi, and is using rsh to log into 2.11 BSD on the PiDP11. The actual data is generated in 2.11 BSD on the PiDP11 in real time. I'm using a script to run the demo because I was not able to hold the handy and type in the commands at the same time. :-)

Technically, the emulator uses 2 drawing surfaces: A persistent one and a fading one. The fading one is used for the bright spot, and the dark mode. These drawing surfaces are combined when the screen is refreshed. As far as I understand it uses the GPU of the Raspberry Pi.

There would be a lot more work to do, and I am not at all convinced that it is worth doing it: Internal rsh implementation, complete code set of the 4020, dark mode, improved handling of screen refresh rates, simulation of baud rates to just name  a few. This would therefore be  a major project lasting several months. I think that it would only make sense to do all of this if there is sufficient interest for such an emulator, because for my own work xterm is actually not good enough. Your feedback is therefore very much appreciated.

[Ian Schofield]

Dear Rene,

 I am very impressed. This is already far better than anything else that is available. I really think this is worth pursuing towards at least a beta version. Also, I think it is entirely reasonable to run it on a separate Pi or, if you are using SDL, on any other system. I take your point about the amount of work to do but I think an implementation of at least a 4010 or 4014 is quite sufficient in the first instance. As I am sure you know, this technology spawned quite a large family of displays from Tek until they were overtaken by bit mapped graphics. Emulating them all would be quite a task. The situation is bad enough with all of the DEC terminals. I am in progress with one in particular ... VT105 (see image). This terminal is another case in point as the graphic system is shall we say, 'interesting'. Its use is very limited ... this plot is generated using MINC Basic under simh. But, as a recreation of an historical artefact, it is of consequence. So, do let us know when you have some code to try.

Regards, Ian.

[Rene Richarz]

A first usable version of my Tektronix 4010 emulator is now available. It was actually much easier to make it than I anticipated. If you are interested and courageous, you can try it. It implements all 4010 features except the graphics input mode. There is also a demo file captured_data, which you can try as described in the repo before hooking the emulator up to a real PiDP-11 operating system. The program gives you the feeling of using a real Tektronix 4010 with the PiDP-11.

The program is in a separate repository: https://github.com/rricharz/Tek4010

I'm looking forward to the first bug report :-)

[Henk Gooijen]

I know it is a bit late, but I thought it would be worth mentioning after all.
This piece of hardware can do some 14.000 points plotting on an old analog oscilloscope and the coordinate range is (0,0) to (4095,4095)!
See https://www.nutsvolts.com/magazine/article/the-arduino-graphics-interface-part-1?hsCtaTracking=8d404bbc-5cfc-44e1-ab72-bf119a508efe%7C8c45e112-1f0e-41ad-b478-40c596eefdb4
The PCB costs $15, parts cost is about the same I guess, plus you need a specific Arduino board. Just read the article.
I have built it, but did not yet have the time to program the Arduino. I have a totally different use for it (an Radar Warning Receiver display in an F-16 simulator).

[Rene Richarz]

There are some very nice pictures and images of the Tektronix 4010 and 4014 at computergraphmuseum, which are worth looking at. This site is a little bit hard to surf, but there are also a lot of other nice pictures and images of ancient systems, including many PDP's etc.

In the mean time I also made a lot of progress with my tek4010 emulator. It can now be run on the same Raspberry Pi as the PiDP-11, and telnet into DZ11 or similar terminal multiplexers.

[oscarv]

Rene,

Your project(s) just got an article on Hackaday:

https://hackaday.com/2019/03/31/a-weather-station-fit-for-a-pdp-11/

Thanks for all the work you put in, it's massively fun and really adds to the 'what shall I do with a PDP-11 today' conundrum!

Kind regards,

Oscar.

[Rene Richarz]

Oscar,

This is really your work and the work of a large number of other people who did not get mentioned in the article. „it doesn‘t get better than that“ !

By the way, I just got all the original plot files which were used to make many of the Tektronix 4010/4014 videos! More to come soon!

Rene

[Rene Richarz]

The Tektronix 4010/4014 emulator project has made very good progress recently, and is a nice addition to demonstrate a PiDP-11. Version 1.1 is released and Oscar will probably add it to the next PiDP-11 software release.

Version 1.2.2 is ready for beta testing. It fully supports the Tektronix 4014. It also includes support for monitors with lower resolution, such as those often used on Raspberry Pi systems. On those displays it is now properly scaled down. Because of the large number of combinations between various monitor sizes, use of vnc, running on the same Raspberry Pi as the PiDP-11 software or on a separate one and running in full screen or windowed mode, I appreciate any brave beta testers. Please keep sending me those bug reports.

Jos Dreesen allowed me recently to have a look at his running Tektronix 4014 and I was able to adjust the appearance of the emulator to mimic the original as much as possible. The only visible difference is that the bright spot on the original is an extremely bright green, whereas I had to choose the brightest possible white in the emulator, because modern displays just don't allow for the same brightness as the storage tube on the original.

You can find the release 1.1 here: https://github.com/rricharz/Tek4010/releases

And the current beta test version here: https://github.com/rricharz/Tek4010

[oscarv]

Rene,

This really is a great addition to the PiDP!

I've used the Tek 4010 simulator over VNC, which works well enough. But I just bought myself a little $50 HDMI 7" display, that now sits permanently next to the PiDP showing the pretty vector graphics demo. Very suave! And as it turns out, easy to program for under 211BSD too.

Kind regards,

Oscar.

[Randy E (OoMOR)]

While not am emulator, I do see that a seller in Southern California has a Tektronix 4006-1 Storage Terminal available. It is said to be in "fair" cosmetic condition, but it is missing several keys from the keyboard as well as the fuse holder cap and power cable. He says it won't power on which considering the missing pieces, isn't exactly a surprise. The User and Service Manual are available for download from Bitsavers, so getting started on patching this up shouldn't be too difficult. (Finishing the project is of course a different matter entirely.)

https://www.ebay.com/itm/VINTAGE-TEKTRONIX-4006-1-11-COMPUTER-MONITOR-DISPLAY-TERMINAL-J-1000-PARTS/333238697746

He also has an interesting pile of Altair 8800 pieces including that seems to be a full case along with (2) front panels in a different auction, but this isn't the S100 group, so I won't mention it... <grin>

Randy

[Richard Stofer]

I have a 4006 that has been in the factory box since about 1980 or so.  Maybe I should drag it out.  I used it as a graphics terminal for UCSD Pascal back in the day.

I also have an Altair 8800 in dubious condition.  I think I pulled the home-built FDD controller and I retrofitted the power supply when I went to 64k of static RAM, back when that was a power hog.  I have thought to resurrect it.  I also have a CompuPro Z80 box, fully loaded, that is known to work with a pair of 8" floppies (and I have the disks).  All of that was superseded when I used a 50 MHz Z80 to run CP/M from a Compact Flash board (again, self-built).  You know, CP/M screams at 50 MHz!

How amazing that a complete macro assembler only required a bit over 30k bytes.

[Rene Richarz]

I have added some plot files of the spacelab made with the tek4010 emulator and the ICEMDDN CAD package made on a CDC Cyber 175 mainframe emulator in my github repo. Thanks to Nick Glazzard for the plot files. These could definitely benefit from a screen with 4K resolution.

[Neal G.]

Rene,
That's excellent. Do you have a link to the Cyber 175 emulator? It has been a very long time since I drew with ICEMDDN; it would be great to spend some time with it again.

[Rene Richarz]

On Thursday, August 15, 2019 at 3:03:53 AM UTC+2, Neal G. wrote:

Rene,
That's excellent. Do you have a link to the Cyber 175 emulator? It has been a very long time since I drew with ICEMDDN; it would be great to spend some time with it again.

Sorry for the late public answer. We have been in contact by other means, but I wanted to post a link here if anybody else is interested in ICEMDDN. Nick Glazzard has made a very substantial effort in the mean time to provide such a link: http://www.hccc.org.uk/nosicem/nosinfo.html. Please accept the license info there, if you are using it.