Here's an album of pictures from this year's VCFMidwest

Here are some pictures I took recently at VCFMW 16 (2021).


But did you have to include the “Free Pile” and “For Sale items”. Not many blinking light machines.
but still nice to see the the all the older machines. Ben.

Thanks for sharing @Parardroyd ! Such a great variety of machines there… including, I’m happy to see, a few Acorn machines, which are not so often seen in the US.



And a couple of Amstrad machines including an NC200 (fit to run Fuzix these days, but shipping with BBC Basic)

Also, HP 21MX which is entirely new to me - with a paper tape reader:

And HP-1000 E series looks very nice

Tektronix 4010 / PDP-11 with some nice monochrome graphics - that’s the sort of thing I worshipped from afar in the 70s

A core memory, I think, from Keronix…

“The jewel-encrusted egg is closed”…

(I hope you’re OK with me pasting a few clippings from your album)

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No problem. Feel Free to re-post as you wish.

Also, you are correct about the paper tape reader. Further into the set there’s a picture of it being used…

Ha ha - “you just creamed a 29 megabuck lander”

I really enjoyed seeing all those pictures! Thanks so much for posting all of them.
I notice the last two pictures of the Logo show an art rendering of the 5150 yet there’s no main pictures of any IBM-PC. I spotted one 5150/60 in the distance that looks like it has the expansion chassis.
Again, thank you!
Carlos, Canada

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BTW, is this Marc Verdiell (AKA CuriousMarc) in the right of the picture of the HP?
This also looks well like what he would put on exhibition.

I have so many questions about this that I don’t even know where to start.

  • Why is that ADM-3A drawing Tek graphics?
  • Where do I get this graphics editor too go with my own PDP-11 and Tek 4010?

I think those are the most critical.

mmm. Wikipedia says - and this could almost be a joke:

Further optional add-ons included a graphics card enabling it to emulate a Tektronix 4014[citation needed]

but there’s an entry on the talk page where someone says they used one:

In one of the two ADM3A terminals I used some 20 years ago there was an additional circuit board mounted on top of the original board, about the same size. The terminal was able of drawing according to the Tektronix Plot-10 standard commands. Sadly to say, the terminal is since long lost.

In searching I kept coming across Visual terminals which emulated both ADM-3A and Tektronix - which is not to say that the ADM didn’t also have that as an option.

Edit: but wait, page 22 of this 1986 document says

Another option provided by LSI is vector drawing graphics, which provides the ADM 3A, ADM 5, ADM 24, ADM 31, ADM 32, and ADM 36 with Tektronix Plot 10 software-compatible graphics capability

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Somehow I have never, ever encountered this before, and I am fascinated. That would require an enormous amount of RAM compared to the character RAM in the ADM-3A, which seems unlikely to be practical given the barebones nature of the 3A. (The Tek logical grid is 1024x1024, with line segments starting and ending on any of those one million points. This is practical in the 40xx terminals only because nothing actually stores the lines in memory, they are simply retained by the surface of the storage tube.)

It looks like him. Seems like a long way for him to go though from CA.

It’s “only” 128KB - which in the late 70’s was achievable (Apple II easily had 64KB of RAM in the late 70’s) It was still expensive in the early 80’s but nowhere near impossible.


1024*1024 is 1 MB, though!

Only about 768 kB of it is actually viewable on screen, and if it’s actually holding a bitmap representation it can discard the last 256 kB after the individual vectors are drawn.

The ADM-3A I assume has only about 2 KB of RAM, normally.

It’s certainly possible (and much more than in the early '70s when the Tek 4010 came out), but it seems like a lot.

I should say – in order to achieve the full resolution of a Tek 4010 requires 1024x1024, I haven’t read the attached documents yet (they’re in the queue!), if the actual terminal is using only 128 kB and displaying a much lower resolution, that makes more sense.

I guess, you could also half the resolution by dropping the last bit of any coordinates, by this reducing memory requirements to 256K.
(Not so sure, whether this image looks like a full 1024 x 1024 resolution, or not.)

BTW, I was suprised to see this, as well.

It looks pretty good to me, if it’s not 1024x1024 it’s using a good algorithm for reduction.

My interpretation is that it was 1024x1024 pixels and at 1 bit per pixel, it’s 1024 rows of 1024 pixels, so 1024 rows of 1024/8 bytes = 1024 * 128 = 131072 bytes, aka 128KB.

Sun did something similar to get their 1152x900x1 graphics squeezed into 128KB too, IIRC. It’s a weird resolution, but close to 4:3 ratio.

But if it really is/was 8 bits per pixel, mono. then that would be “expensive/wow” for the late 70’s…


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Oh, duh, yeah. I didn’t stop to think about the fact that it’s a monochrome display. 1 Mb, not one MB! (I really do know better…)


At work (New York State Agricultural Experiment Station at Geneva, NY) we used to have an ADM-3A with a Retro-Graphics add-on board from Digital Engineering Inc. I think the add-on board model we had was the RG-512 described here. We even had a hardcopy unit attached to it that “printed” (burned/heated) an image into paper with a thin aluminum coating. We used it on a Prime 800 timesharing minicomputer. My recollection is that the graphics were reasonably good looking, especially when put onto hardcopy, but not as high-resolation as a Tektronix 4010 terminal we had connected to the same Prime 800.

I don’t recall the resolution of the RG-512, but this write-up says its resolution was 512 × 250. That fits with my memory of the RG-512 looking reasonable but blockier than a Tektronix 4010.

To the best of my recollection, we used the same plotter definition for both the Tektronix 4010 and the Lear-Siegler ADM-3A with Retro-Graphics board, so the RG-512 probably mapped the Tektronix 1024x780 coordinates onto the RG-512 512x250 coordinates.


That’s great info @zamp thanks! And a nice link to a 1979 book. (Acorn’s BBC Micro likewise uses a 1280x1024 virtual space for graphics, but reduces to the actual resolution according to the screen mode.)

Edit: user manual here, and here’s a flyer.