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When the Mark-8 Minicomputer made it's debut on the cover of Radio Electronics in July of 1974, it drew the attention of an unusually large number of entrepreneurs. Within just a couple of months, newsletters had began, and companies started or moved to supply hobbyist with parts and information in the new field of personal computing. One of those moving quickly was Dr. Robert Suding, who founded, or was a founding member of the digital group. Among the first products designed by Dr. Suding to be offered by the digital group was a video card, as seen here, part of my TV Typewriter. This card was not intended as a stand-alone TV Typewriter so much as it was a direct addition to the Mark-8 itself.
 

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It took me quite a while to decide what to do with my video card. I did not want to add it directly to my Mark-8, as I wanted to preserve the Mark-8 in original condition, but did not have any alternative ideas that seemed acceptable. I also knew that I would want to use it with my Mark-8 in some way, since it was originally designed specifically for the Mark-8. After having plastic covers made for a few of my other machines, I decided to build a cabinet completely out of plastic. The challenge was to make it attractive and functional. The keyboard used was a complete unknown, picked up for an incredible price of just $2.50, and it is configured and labeled just like my ASR-33 keyboard, which I thought was a great bonus. I added lower case capability to the keyboard by a toggle switch on the rear panel, and the key pressed strobe has a selectable connection to the Mark-8 interrupt line via another rear panel toggle. This allows programming to handle keyboard operations through interrupts, a useful tactic for many applications.

The monitor shown is a surplus item I picked up about ten years ago. The housing was designed by me and made by Hawkeye plastics.

Operation

The operation of the TVT is a little clumsy and a bit off-beat. Although the keyboard will encode all of the standard control characters, the video card does not recognize anything but a "home" command. This means there is no cursor, no cursor functions such as a backspace , up or down movement, etc. Worst of all, no screen erase, carriage return or line feed! All of this must be implemented in software if it is desired! Otherwise, it works great! 

The screen shows eight lines of thirty-two characters per line. Quite small, but very usable. It is functional as a stand alone TVT by use of a jumper plug that fits into the output connector, looping the keyboard outputs to the video card inputs. It also plugs directly into my Mark-8 rear connector.
 

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