TV Typewriter
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The TV Typewriter is a video terminal that could display two pages of 16 lines of 32 upper case characters on a standard
television set A television set or television receiver, more commonly called the television, TV, TV set, telly, tele, or tube, is a device that combines a tuner, display, and loudspeakers, for the purpose of viewing and hearing television broadcasts, or using ...
. The design, by
Don Lancaster Donald E. Lancaster is an American author, inventor, and microcomputer pioneer. Background Lancaster is a writer and engineer, who authored multiple articles for computer and electronics magazines of the 1970s, including ''Popular Electronics' ...
, appeared on the cover of ''
Radio-Electronics ''Radio-Electronics'' was an American electronics magazine that was published under various titles from 1929 to 2003. Hugo Gernsback, sometimes called the father of science fiction, started it as ''Radio-Craft'' in July 1929. The title was changed ...
'' magazine in September 1973. The magazine included a 6-page description of the design but readers could send off for a 16-page package of construction details. ''Radio-Electronics'' sold thousands of copies for $2.00 each. The TV Typewriter is considered a milestone in the home computer revolution along with the
Mark-8 The Mark-8 is a microcomputer design from 1974, based on the Intel 8008 CPU (which was the world's first 8-bit microprocessor). The Mark-8 was designed by Jonathan Titus, a Virginia Tech graduate student in Chemistry. After building the machine ...
and
Altair 8800 The Altair 8800 is a microcomputer designed in 1974 by MITS and based on the Intel 8080 CPU. Interest grew quickly after it was featured on the cover of the January 1975 issue of Popular Electronics and was sold by mail order through advertiseme ...
computers. "A giant step toward the realization of the personal-computer dream happened in 1973, when Radio Electronics published an article by Don Lancaster that described a 'TV Typewriter'.""One influential project was the TV-Typewriter, designed by Don Lancaster and published in ''Radio-Electronics'' in September 1973." Sometimes the term was used generically for any interactive computer display on a screen; until CRT displays were developed, the
teleprinter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initia ...
was the standard output medium.


Don Lancaster's TVT I

Don Lancaster was an engineer at
Goodyear Aerospace Goodyear Aerospace Corporation (GAC) was the aerospace and defense subsidiary of the Goodyear Tire and Rubber Company. The company was originally operated as a division within Goodyear as the Goodyear Zeppelin Corporation, part of a joint project ...
designing a high resolution video display for the military. Don was also a prolific author of hobbyist projects for ''
Popular Electronics ''Popular Electronics'' was an American magazine published by John August Media, LLC, and hosted at TechnicaCuriosa.com. The magazine was started by Ziff-Davis Publishing Company in October 1954 for electronics hobbyists and experimenters. It soo ...
'' and ''
Radio-Electronics ''Radio-Electronics'' was an American electronics magazine that was published under various titles from 1929 to 2003. Hugo Gernsback, sometimes called the father of science fiction, started it as ''Radio-Craft'' in July 1929. The title was changed ...
'' magazines. The video project gave Don the inspiration for his most influential project, a low cost video terminal known as the TV Typewriter. Built in the era before widespread availability of low-cost
microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
s or solid-state
computer memory In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and digital electronic devices. The term ''memory'' is often synonymous with the term ''primary storage ...
, the system used
small-scale integration An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...
TTL digital logic and
shift register A shift register is a type of digital circuit using a cascade of flip-flops where the output of one flip-flop is connected to the input of the next. They share a single clock signal, which causes the data stored in the system to shift from one loc ...
memory. Much of the circuitry was involved in timing the output of the analog generator with the memory, which had to be shifted bit-at-a-time to the output. On-screen text was generated by the Signetics 2513, one of the first
character generator A character generator, often abbreviated as CG, is a device or software that produces static or animated text (such as news crawls and credits rolls) for keying into a video stream. Modern character generators are computer-based, and they can g ...
integrated circuits. The article appeared in the September 1973 issue. In addition to the six-page article, they also offered to ship out a larger 16-page version with complete layout plans for a mail-in fee of $2. Given its limited functionality, they initially estimated that the magazine would sell about 20 copies of the plans for each. Instead, they were flooded by requests and eventually sent out 10,000 copies. With professional terminals costing over this kit looked like a bargain. In the November issue, the editors apologized for the delays in shipping the TV Typewriter booklets to the thousands of readers that ordered them. They also listed electronics parts sources for the difficult to find components. Don Lancaster also answered a series of reader questions and gave ideas for additional functions and uses for the TV Typewriter. The December issue had a page of corrections for the TV Typewriter booklet. Both of the notices were included in later printings of the booklet. The compact design and complex circuitry made the TV Typewriter a challenging project for hobbyists. But many finished the project and some even connected it to their
Intel 8008 The Intel 8008 ("''eight-thousand-eight''" or "''eighty-oh-eight''") is an early byte-oriented microprocessor designed by Computer Terminal Corporation (CTC), implemented and manufactured by Intel, and introduced in April 1972. It is an 8-bit CP ...
based computers. The April 1975 issue of the ''Micro-8 Newsletter'' has 6 pages of user modifications and interface designs to connect the TV Typewriter to
Mark-8 The Mark-8 is a microcomputer design from 1974, based on the Intel 8008 CPU (which was the world's first 8-bit microprocessor). The Mark-8 was designed by Jonathan Titus, a Virginia Tech graduate student in Chemistry. After building the machine ...
or
SCELBI SCELBI was an early model of microcomputer based on the Intel 8008 processor. The company SCELBI (derived from SCIentific-ELectronics-BIology) Computer Consulting in 1973, by Nat Wadsworth. The SCELBI 8H was marketed in 1974 and was delivered eith ...
computers. The original TV Typewriter design did not include a serial interface, modem connection, or offline data storage on cassette tape. Don Lancaster wrote about these in the September 1975 issue of ''BYTE'' magazine and his TV Typewriter Cookbook. A serial interface board designed by Roger Smith was published in the February 1975 issue of ''Radio Electronics''.


Keyboards

Today keyboards are readily available and inexpensive, and they have a standard interface. In 1973, new keyboards were only available to computer and terminal manufacturers. Surplus keyboards were available to hobbyists but they often produced codes other than
ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because of ...
, such as Baudot or
EBCDIC Extended Binary Coded Decimal Interchange Code (EBCDIC; ) is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. It descended from the code used with punched cards and the corresponding six- ...
. The TV Typewriter project and kit did not include a keyboard. The unit on the September cover shows a keyboard project Don Lancaster did in the February 1973 issue. This project involved hand crafting 55 key-switches including fabricating the springs for each key-switch. Most hobbyists chose to use a surplus keyboard and modified it to produce ASCII codes. Don Lancaster's prototype TV Typewriter which is now on display at the
Computer History Museum The Computer History Museum (CHM) is a museum of computer history, located in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the information age, and explores the computing revolution and its impact on ...
has a surplus keyboard with an ASCII encoder circuit that was published in the February 1974 issue of Radio-Electronics. The plans for this encoder were also included in the TV Typewriter booklet ''Popular Electronics'' (April 1974) featured a complete keyboard kit designed by Don Lancaster and available from Southwest Technical Products for $39.50. The first version used simple RTL ICs to decode the key matrix. The design was soon improved to use a full featured keyboard encoder IC.


SWTPC CT-1024

Southwest Technical Products got their start selling sets of bare circuit boards for and the eight major integrated circuits for . The hobbyist had to acquire the rest of the components on their own. The original TV Typewriter was difficult to assemble and some of the ICs were going out of production so Southwest Technical Products decided to redesign the kit. The replacement was featured in Radio Electronics as the TV Typewriter II. This time readers did not have to order a set of plans, since the complete design was published in 6 issues starting in February 1975. Daniel Meyer of
SWTPC Southwest Technical Products Corporation, or SWTPC, was an American producer of electronic kits, and later complete computer systems. It was incorporated in 1967 in San Antonio, Texas, succeeding the Daniel E. Meyer Company. In 1990, SWTPC beca ...
enlisted Ed Colle, an engineer who had worked at
Datapoint Datapoint Corporation, originally known as Computer Terminal Corporation (CTC), was a computer company based in San Antonio, Texas, United States. Founded in July 1968 by Phil Ray and Gus Roche, its first products were, as the company's initial ...
on terminal design, to design the new TV Typewriter. The SWTPC CT-1024 Terminal displayed 32 characters by 16 lines without scrolling. It used common TTL parts and 2102 static RAMs. The boards were laid out with very loose part spacing and wide traces to make it easy to assemble. A complete set of option boards was offered including a serial interface. The keyboard was based on Don Lancaster’s design. The rest of the terminal was done by Ed Colle. The design was finished by late 1974 and the kits were ready for sale by December 1974. The first advertisement for the CT-1024 appeared in the January 1975 issue of Popular Electronics on the page facing the Altair 8800 computer article. The full page advertisement, "SWTPC is Proud to Announce the CT-1024 Terminal System", appeared on page 32. The Altair 8800 article started on page 33. The CT-1024 was very successful because a complete kit with options cost only . It was replaced in 1977 by the improved CT-64 that offered scrolling and 64 characters per line of upper and lower case.


''TV Typewriter Cookbook''

By 1975, Don Lancaster had written over 100 articles in magazines such as ''
Popular Electronics ''Popular Electronics'' was an American magazine published by John August Media, LLC, and hosted at TechnicaCuriosa.com. The magazine was started by Ziff-Davis Publishing Company in October 1954 for electronics hobbyists and experimenters. It soo ...
'' and ''
Radio-Electronics ''Radio-Electronics'' was an American electronics magazine that was published under various titles from 1929 to 2003. Hugo Gernsback, sometimes called the father of science fiction, started it as ''Radio-Craft'' in July 1929. The title was changed ...
''. He had also written a digital design book titled the ''RTL Cookbook'' in 1968.
Resistor–transistor logic Resistor–transistor logic (RTL) (sometimes also transistor–resistor logic (TRL)) is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices. RTL is the earliest class o ...
(RTL) was an early IC technology that was replaced by
TTL TTL may refer to: Photography * Through-the-lens metering, a camera feature * Zenit TTL, an SLR film camera named for its TTL metering capability Technology * Time to live, a computer data lifespan-limiting mechanism * Transistor–transistor lo ...
, so in 1974 he published the ''TTL Cookbook''. This book was in print for 20 years and sold a million copies. The original TV Typewriter was designed before low cost
RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...
was available and the design was soon obsolete. Don had made many design improvements and published them as the ''TV Typewriter Cookbook'' in 1976. Portions had been serialized in the first issues of
Byte magazine ''Byte'' (stylized as ''BYTE'') was a microcomputer magazine, influential in the late 1970s and throughout the 1980s because of its wide-ranging editorial coverage. "''Byte'' magazine, the leading publication serving the homebrew market ..." '' ...
. The book was a guide on how to design a video computer terminal, divided into the following chapters: # "Some Basics" # "Integrated Circuits for TVT Use" # "Memory" # "System Timing – Calculation and Circuits" # "Cursor and Update Circuits" # "Keyboards and Encoders" # "Serial Interfaces" # "Television Interfaces" # "Hard Copy and Color Graphics" This book guided many hobbyist and professionals in designing video displays for home computer systems. The cassette interface design from chapter 7 was the basis for the
Kansas City standard The Kansas City standard (KCS), or ''Byte'' standard, is a data storage protocol for standard cassette tapes at . It originated in a symposium sponsored by Byte (magazine), ''Byte'' magazine in November 1975 in Kansas City, Missouri to develop a ...
. The circuits in this book did not rely on a microprocessor, just TTL. The ''TV Cheap Video Cookbook'' (1978) showed the TVT 6 5/8 that would work with a
6502 The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit microprocessor that was designed by a small te ...
or 6800 microprocessor. The design was targeted at the
KIM-1 The KIM-1, short for ''Keyboard Input Monitor'', is a small 6502-based single-board computer developed and produced by MOS Technology, Inc. and launched in 1976. It was very successful in that period, due to its low price (thanks to the inexpe ...
Microcomputer. The original TV Typewriter book cover shows an ASCII keyboard designed by Don Lancaster and sold by Southwest Technical Products. An early computer store chain, the
Byte Shop The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
, had the publisher add their logo to the covers and sold the ''TTL Cookbook'' and the ''TV Typewriter Cookbook'' in their stores. A later edition cover was designed for
Radio Shack RadioShack, formerly RadioShack Corporation, is an American retailer founded in 1921. At its peak in 1999, RadioShack operated over 8,000 worldwide stores named RadioShack or Tandy Electronics in the United States, Mexico, United Kingdom, Austra ...
stores. The ninth printing of the first edition was in 1983.


See also

*
History of computing hardware (1960s–present) The history of computing hardware starting at 1960 is marked by the conversion from vacuum tube to solid-state devices such as transistors and then integrated circuit (IC) chips. Around 1953 to 1959, discrete transistors started being considered ...
*
Personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or tec ...


References


Bibliography

; Magazine
Radio-Electronics; September 1973.
; Books * * * * * ; Construction articles for TVT I * * * * * * * * * ; Construction articles for TVT II * * * * * * ; Construction articles for TVT-6 * * Has video software written in 6502 assembly language for the KIM-1 microcomputer. * ; TV Typewriter Cookbook serialized in BYTE magazine * * * * {{refend


External links




Don Lancaster's autobiography
Early microcomputers Character-oriented terminal