Hand-held Calculators

Home > Hand-held Calculators

TSI Speech+ & other speaking calculators

In the early 1970s, with the advances in electronics, there was considerable effort to produce a calculator for use by the blind, as outlined in the article Calculators for the Blind on this site.

The Telesensory Systems Inc. Speech+ shown here was the first commercial hand-held talking calculator for the blind.  Also on this page is a talking calculator aimed as and educational aid for youngsters.

Speech +

Speech+ speaking calculator with audio cassette with operating instructions. 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, to aid the blind in using it, 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 commercial hand-held speaking electronic calculator.

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

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").

Went on sale in 1976, costing US$395[1].

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

Designed for use by the blind.  The top photograph shows the audio cassette tape which carries the operating instructions.

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.

Very noticeable is the keypad with the numbers arranged 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), to aid a blind user familiar with operating a telephone keypad.

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 commercial hand-held speaking calculator and a very early use of speech synthesis in a consumer product.

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

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.  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".


The article Calculators for the Blind on this site outlines some of the early efforts to produce a calculator for use by the blind, either by using sound or Braille output.

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 TMS1000NLL 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".

Note that this machine uses the standard arrangement of keys on the calculator keypad, unlike the Speech+ models which are designed for use by the blind, who may be familiar with the arrangement of keys on telephone keypads.

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. "A Talking Calculator", Popular Electronics, May 1976, p24.

Hand-held Calculators

Vintage Calculators

Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.