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TSI Speech+ & other speaking calculators

Speech +

Speech+ speaking calculator with instructions on cassette. The knob at top right is pulled to turn the calculator on and then acts as a volume control. Pressing the button with the loudspeaker symbol (below the "=" button) makes the calculator speak the number on the display. The switch below this button can be used to switch off the speech system.

An interesting point is that the numbers on the keypad are in the same order as a phone (with 1 at the top) rather than the normal order for a calculator (with 9 at the top).

Telesensory Systems Inc. Speech+

Distinctive features: The first speaking electronic calculator.

Technical details:
Display is 8 digits, red LED. Also speaks the keys pressed and the result.

4-function, %, memory, square root.

Calculator integrated circuit: Texas Instruments TMC1007NL (here date coded mid-1976), based on the TMS1000 4-bit micro-controller. "TSI has custom-programmed a microcomputer in the SPEECH PLUS calculator and is a pioneer in the use of this device. This microcomputer contains the calculating capability. It was used instead of more-conventional, commercially available parts so that we could dictate the way the calculator works and design the keyboard. ..."

Speech processing integrated circuits: Telesensory Systems Inc S14001A, General Instruments S14007 (here both date coded early 1977). "The speech circuit for the 24 word vocabulary involves patent pending technology. The speaker is the only moving part and there are two large scale integrated circuits. One is a custom, special purpose microprocessor TSI developed to replace 50 separate integrated circuit packages. The other is a TSI-programmed Read Only Memory (ROM) which has a copyrighted output."

4.8v (4x AA rechargeable).

180 x 115 x 35 mm. (7.1" x 4.5" x 1.4").


Made in USA by Telesensory Systems Inc., Palo Alto, California.

Designed for use by the blind. The top photograph shows the instructions on cassette tape.

Front cover removed

With front cover removed, showing the Texas Instruments micro-controller, used as a calculator chip, and the LED display assembly above the keyboard.

Speech board

The lower, speech circuit board, with the TSI S14001A speech integrated circuit above and the GI S14007 mask ROM chip with the speech data below, the speaker, & the rechargeable cells.

This was the first speaking calculator and a very early use of speech synthesis in a consumer product.

There had been considerable effort to produce a calculator for use by the blind.
An earlier attempt was recorded in the journal New Scientist in October 1973 in the report of a meeting of the British Computer Association of the Blind (BCAB) in Reading[UK.][1]:
"New devices help scientists read and add ...
    Another device on display at Reading was a desk calculator developed by the Clarendon Lab of Oxford University which gives results aurally.  It uses tones for numbers: a long low for one, a long low plus a short for two, a long low plus two shorts for three, up to five which is a high long, then six is a high long plus a high short, etc.  The decimal is indicated by a click.  Twelve units are being built for the Royal National Institute for the Blind (RNIB), and in production the unit would probably cost £250
[GBP, about US$600].  Coleman says that 17 labs, including five in England, were working on blind calculators."


Dale Hill has put a video of a Speech+ calculator in operation on YouTube, so that you are able to hear it there.

The TSI S14001A was developed by TeleSensory, Inc. and Silicon Systems, Inc. in 1975 as a single-IC speech chip for the Speech+ portable talking calculator for the blind.  The speech technology was licensed from Forrest S. Mozer, a professor of atomic physics (speech was a spare time thing for him) at University of California, Berkeley[2].

Ed Bernard worked for Silicon Systems, Inc., and was the design engineer for the S14001A speech chip.  Ed has kindly provided detailed information about the chip in the article on this site "The Development of the TSI Speech+ Calculator".

APH Student Speech+
Rear of APH Student Speech+

APH Student Speech+

The photographs of this less common version of the Speech+ were kindly provided by Erik Sylvia.

This outwardly appears to be identical to the usual TSI Speech+ but was supplied by APH, "American Printing House for the Blind, Inc.".

The label on the rear shows that it was made by TSI, but the serial number appears to incorporate the model number "S1D" whereas the usual TSI version is "S1A".

Child's Teaching Speaking Calculator

Child’s Teaching Speaking Calculator

Child's Teaching calculator

Distinctive features: Speaking electronic calculator.

Technical details:Display is 6 digits, red LED, and speaks.

4-functions and maths test mode.

Integrated circuits - Texas Instruments TMS 1000NLL 4-bit micro-controller (here date coded to early 1978) and SN99857.  The micro-controller here is another version of the device used in the Speech+ above.

185 x 150 x 29 mm / 7.25 x 5.9 x 1.1".

Manufacturer unknown, made in Hong Kong.
If you know of the manufacturer/distributor please contact us.


With the rear cover removed. The single small circuit board carries the two integrated circuits and the few other components..


  1. "New devices help scientists read and add ...", New Scientist, 4 October 1973, p24.
  2. Gevaryahu,Jonathan, "TSI S14001A Speech Synthesizer LSI Integrated Circuit Guide", https://archive.org/stream/pdfy-QPCSwTWiFz1u9WU_/david_djvu.txt.

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