VT-69 Handheld Terminal

It's a dumb terminal. You can connect a Raspberry Pi to it.

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It's a badge that's a dumb terminal. It doesn't actually *do* anything, because dumb terminals don't actually do anything. It's just a keyboard and a screen. It'll teach you the difference between a DB-25 and a DE-9.


Hardware Specs / Function

It's a dumb terminal. It doesn't do anything. You can wear it around your neck. It's got a keyboard and a screen. 

WHAT: This is a dumb terminal. That means it doesn't compute anything. This is not a computer, it is effectively a teletype you can put in your pocket. To use this device, you must connect it to a computer. Again, this hardware does nothing, because it is a dumb terminal.

WHY: doesn't this do anything? Because it's a dumb terminal you can fit in your pocket You can connect it to other computers! Again, this is a dumb terminal, with a keyboard, that will fit in your pocket. Because this should exist. Oh yeah, you might be able to put a Raspberry Pi in it, so that it can become a computer.

WHAT: up! We're three cool guys looking for other cool guys who want to hang out in our party mansion! Nothing Sexual. Dudes in good shape encouraged, but if you're fat, we expect you to find humor in the little things. Again, nothing sexual.

TWITTER: Yeah go here or something

SPECS: Built around the ATSamD21 series of microcontrollers and an 800x480 pixel display. It has a silicone keyboard (like a remote control), and enough space for a big 'ol LiPo battery. Ports are USB-C and a DE-9. That's it.

  • No gods. No masters. No frame buffers. No external libraries.

    Benchoff05/23/2020 at 19:31 1 comment

    A terminal requires a 'new line' command. Therefore, I need some way to move all the characters up one line. The conventional way to do this is to keep a circular array of all the characters on the screen, and whenever a new line character is sent (or pressed), I would redraw the entire screen.

    No, wait, scratch that. The conventional way to do this is by selecting a display with a hardware scrolling function.

    Alternatively, I could keep the entire display in a frame buffer and write it out constantly, shifting up one character line whenever there's a new line command.

    The math: Keeping the contents of the display in memory as characters requires at least 1840 bytes (80 characters by 23 lines, because we don't really care about the top line of characters.) Keeping the entire display in memory as a bitmap requires at least 48000 bytes (800x480 at 1bpp, with some bitstuffing). Both of these options are onerous, so here's a way to scroll an entire display in 58 bytes.

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  • Font Rendering Speed++

    Benchoff04/29/2020 at 16:45 1 comment

    On the advice of someone who's actually helpful on Twitter I've spent the last few days finishing the font set (ASCII Extended code page 437, the old DOS extended ASCII with those weird 'box' characters), and optimizing the font rendering speed. First, the results:

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  • You can make a baby and a bitmap in nine months

    Benchoff10/16/2019 at 17:42 3 comments

    The last update for this project was a realization that a 'dumb' display would cost too much; the driver chip was too expensive, and if I didn't want to go with a driver chip, the microcontroller would be too expensive. The solution to this problem was to use a display with built-in graphics RAM, in this case a display with the NT35510 controller chip. There's a problem with this solution - no one has a driver for this display, or at least one that is portable to other (read: modern) microcontrollers.

    ...Which means I need to write a TFT driver. This took nine months. Here's the result:

    Read more »

  • Unit Cost And Economics

    Benchoff05/01/2019 at 04:12 3 comments

    Right now, I have the schematic and design done enough that I can get some quotes and go through the actual cost engineering of the VT-69. The TL;DR, is that this would cost more than you would pay.

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  • System Design, Previous Work

    Benchoff04/18/2019 at 17:21 0 comments

    The core feature of the Dumb Badge is to provide an 80x24 character display, with a keyboard, and a serial port. The first requirement of a high-resolution display is the hardest requirement, but there are many cell phone screens that will give you 800x480 pixel resolution, conveniently the same width as the display in a DEC VT100. The display is therefore the hardest part of this project, and demands specific engineering decisions. The purpose of this project log is to discuss these engineering decisions, while covering earlier work done by others.

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  • A Design Study

    Benchoff03/14/2019 at 20:48 2 comments

    I am designing the Dumb Badge with the idea that is a product, not a single one-off project. Being a product demands some work must go into the design, both the design language of the enclosure, but also the typefaces and logotype of the screenprinting and packaging. Basically, I need to decide on a font or two. It's also time to start designing the enclosure, which means I need to imagine what a product made in the alternative history of 1991 would look like.

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  • The Prototype Keyboard

    Benchoff03/02/2019 at 20:05 0 comments

    I'm buying a thousand silicone keyboards, months before I have finalized hardware. I need a way to test the samples of these keyboards, and the easiest way is to turn them into a USB keyboard.

    The TL;DR is that everything is on the Gits

    Read more »

  • On the subject of keyboards

    Benchoff02/10/2019 at 18:51 3 comments

    The dumb badge requires a keyboard, and I'm doing this with a silicone keyboard like you'd find in a remote control or a ZX Spectrum. That's the easiest and cheapest way to put 100 buttons on something. But what is the layout going to look like? It's time for a review of existing terminal keyboards, how I made my keyboard, and a neat testing apparatus.

    Read more »

View all 8 project logs

Enjoy this project?



zpekic wrote 04/22/2022 at 02:19 point

Love this project, hope to see it in a kit form soon? It is actually quite a fancy little device, it could be used with many SBC (single board computers) for example that rely on serial I/O for interaction. As far as really dumb terminals, here is one I wrote in microcode:

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Alysson Rowan wrote 08/12/2020 at 12:53 point

I adore this!
Sometimes, I just want to interrogate a piece of logging equipment without the insanity of programming a GUI interface. THIS would be ideal.

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Koen van Vliet wrote 02/19/2020 at 11:49 point

That's some really sexy product design. I am a fan!

I used to have a Psion pocket computer which had a builtin terminal program. Unfortunately it broke down. It was really nice to have a small portable terminal with the integrated screen and keyboard. I wish you success with your project!

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Techokami wrote 04/09/2019 at 19:38 point

So I know this is going to be mainly a thing given out at conferences and such. But, as someone who is really interested in this project and would like to get one of these, yet cannot travel out to these conferences, would you be willing to sell some on Tindie?

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Benchoff wrote 04/09/2019 at 21:30 point

The plan is to do the launch at cons, and that'll be testing, looking at the future features needed, and improving what I've done until that point.

After that, I'll move into larger-scale production, and they'll be on Tindie.

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fabian wrote 04/06/2019 at 10:25 point

Why not open/closing similar laptop and meybe proportion of screen , look at zx88 cambridge 

If You think about working version please add a big utf-8 charset. Nerd Fonts for powerline for example and add some programaly keys (remember many languages need altgr for working)

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Daren Schwenke wrote 02/11/2019 at 04:12 point

Building tools for tools, for tools.  Right up my alley.

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