How significant and pioneering was the TV Typewriter, in light of things like calculators with CRT's from 1964 and various other things? I recently read that the TV Typewriter established the standard for the cassette-data-storage format (for storing pages of text), and also had a modem eventually.

My question may be too broad, but I have been as specific as I know how.

  • I didn't use my TV Typewriter II with a cassette interface. The Kansas City Standard meeting was in Nov 75, and cassette interface kits/products showed up in 76. The original TV Typewriter and II appeared in 73/74, Serial interface boards (needed) in 75. I used an optical paper tape readers to load my MITS Altair 8800, I had access to an ASR-33 (easier editing). The controlling factor for terminal cost was CRTs. You could buy a RadioShack 7 inch TV for $59. Lear Siegler ADM-3 terminals were $795 in July 75.
    – user9041
    Dec 5, 2018 at 4:15

2 Answers 2


The real, lasting, significance of the TVT was to inspire Lee Felsenstein to actually sit down and design his Tom Swift Terminal.

Lee was a sysop on the first BBS, Community Memory. The main problem with the system is that it used a $1,500 ASR-33 terminal and a $300 modem. He had already fixed the modem problem by inventing the Pennywhistle modem, which cost about $100. But the terminal remained a problem.

When he saw the TVT, he began adapting it as the basis for a low-cost glass terminal. He called and asked Lancaster why he hadn't made it into a terminal, and Lancaster replied he just didn't think of it. So Lee did, combining the TVT with a 1k RAM and a serial and (4-bit?) parallel interface. The idea was that you would put a TV on the TVT output, a keyboard on the parallel, a Pennywhistle on the serial, and then you could connect to Community Memory.

However, by the time he was getting interested in this, Community Memory was going through its death throws. He released the plans in 1974, but in the end no one ever built a Tom Swift. But the timing was just so that in less than a year of Felsenstein passing around the Tom Swift design, the Altair 8800 was launched.

Felsenstein had recently decided to share the rent on a garage with Bob Marsh so he could make a Tom Swift. Marsh wanted to make LED clocks, but when he saw the Altair he got Felsenstein to convert the TVT into the world's first video card, the VDM-1. This was done by adding 1k of memory and interface circuits to the TVT. 1k was why S-100 machines had the "odd" layout of 64-column by 16-row text display, as 64x16=1024=1k. The agreement was that if he did that, Marsh would fund the development of the terminal as a whole.

At the same time, Les Solomon decided someone should convert the TVT into a low-cost terminal for Altair owners - at that point a glass terminal cost about the same as a brand new VB Bug (Super no less). His first attempt did not go well - he took Lancaster to meet MITS, and a shouting match broke out. So he approached Marsh, and March approached Felsenstein again, and now, at long last, the Tom Swift was definitely, totally going to happen.

But when March priced out the design using an 8080, and Felsenstein did the same with his original discrete components, the difference was $10. They decided to go with the 8080, and would make it into a terminal using a terminal program in a ROM. The then packaged a generic 8080 mobo along with a VDM-1, I/O card and a power supply into a case and called it the Sol-20

The Sol-20 was first true personal computer, IMHO, as previous machines required separate terminals for output. So... depending on your point of view, although the TVT was likely only used by a few hundred people for a couple of months of playing around, it indirectly helped spawn the home computer.

  • 1
    Why would one need to add RAM to convert the TVT into a terminal? The TVT was able to use dynamic shift registers to hold the display contents (so did the Apple I, for that matter). Did the TST do anything with its display memory that couldn't have been done with shift registers?
    – supercat
    Dec 13, 2018 at 20:34
  • 1
    What was a VB Bug? Nov 12, 2020 at 14:13

The TV Typewriter was the first popular device to transcribe digital output into a standards-compliant raster scan that could be fed directly to an off-the-shelf TV.

That contrasts with:

  • preceding CRT calculators, which were vector rather than raster based — often dedicated circuits produced the specific deflection pattern for each character; e.g. start from "The beam of the CRT was swept across the screen to write the strokes that made up the individual characters; it was a vector scan, not a raster scan." in this description of 1964's EC-130; and
  • teletypes such as 1969's Datapoint 3300 that were dedicated, expensive devices, no more readily available that the computers of 1969.

So its significance — like the Altair, the trinity of 1977, and the other notables of the home computer boom — lies in the massive broadening of potential users.

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    I'd agree. You couldn't swing a dead acoustic coupler during that decade without hitting an article on making your own TV Typewriter. I think it was 3% of all TAB book content at one point.
    – user12
    Dec 5, 2018 at 18:42
  • @Wilson A web search on "TAB books" will certainly be more useful than any soon-to-be-dead link I can provide here! But venerable imprint that was the basis for many hacker libraries back in the day.
    – user12
    Dec 10, 2018 at 15:52
  • Nice pun there @jdv, I wonder how many get it? Feb 1, 2019 at 15:00

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