I was an avid reader of Radio Electronics magazine. I don\u2019t think I ever missed an issue. When the TV Typewriter article was published in September 1973, I had to have one. The magazine article was just the highlights of the design, so I sent off for the detailed construction package. When it arrived, I immediately began fabricating the boards with Radio Shack PCB blanks and a resist pen. I was too poor (or cheap) to purchase the ready-made boards. I also started scrounging parts. I managed to get nearly everything I needed from Poly Packs and Digi-Key, but I could not afford the MOS components (the 2524 and 2518 shift registers and the 2513 character generator), so I wound up begging my parents to buy the MOS chips for my Christmas. I placed the order with James Electronics (now Jameco) over the phone and my mom drove me to the other side of Belmont, CA to pick up the order.<\/p>\n\n\n\n
In typical tightwad fashion, I fatefully decided to not order the male Molex connectors for the boards. I cut lengths of 14 AWG bare copper wire pieces (probably pulled from scraps of electrical cables) and soldered them to the board pads instead. Although it initially seemed to work, I later decided to tin them with solder. It would have helped if I had cleaned the flux off \ud83d\ude44\u2026 The board stack would occasionally require a bit of flexing to re-seat the connectors when the unit would act up.<\/p>\n\n\n\n
After the project was built, all it could do was to display characters I entered one at a time using a numeric keypad. Of course, I was too cheap to buy a real keyboard. Although I was pleased to have gotten the thing to work, I got the idea that I could possibly adapt it to be a poor man\u2019s Teletype.<\/p>\n\n\n\n
I managed to find an affordable keyboard. Back in 1974, that was quite a feat. I then designed and built a serial port and terminal add-on board using an AY-5-1013 UART and some glue logic to do the lower to upper-case translation and decoding the CR, LF, NUL, and BEL control characters. There was a DB-25 connector that provided TTL level communication at 110 or 300 baud. I also fabricated a metal enclosure for the whole thing at the high school.<\/p>\n\n\n\n
I found a gutted acoustic coupler with no electronics. I designed a 300 baud modem from an Intersil 8038 for the FSK transmit and some Exar chip for the decoder. I now had the ability to connect with the high school district\u2019s HP 2000E timeshare Basic computer. I could now \u201cwork from home.\u201d At only 16 lines of 32 upper-case characters, it wasn\u2019t great. But it was better than anyone else had at home at the time!<\/p>\n\n\n\n
That acoustic coupler modem is all that remains of the TV Typewriter. There are no surviving schematics of the add-on board or the modem. Maybe one of these days, I will open up the modem and trace it out.<\/p>\n","protected":false},"excerpt":{"rendered":"
I was an avid reader of Radio Electronics magazine. I don\u2019t think I ever missed an issue. When the TV Typewriter article was published in September 1973, I had to have one. The magazine article was just the highlights of the design, so I sent off for the detailed construction package. When it arrived, I […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":130,"menu_order":1974,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/pages\/153"}],"collection":[{"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/comments?post=153"}],"version-history":[{"count":5,"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/pages\/153\/revisions"}],"predecessor-version":[{"id":313,"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/pages\/153\/revisions\/313"}],"up":[{"embeddable":true,"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/pages\/130"}],"wp:attachment":[{"href":"https:\/\/robertweatherford.com\/index.php\/wp-json\/wp\/v2\/media?parent=153"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}