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Texas Instruments TMS0952

Features

With the TMS0952 Texas Instruments introduced in the year 1975 the first "real" single-chip calculator design. Read more about the associated TMS1000 family here. In opposite to the TMS0102 with the discrete segment- and digit-drivers or the TMS0803 with the external digit-drivers this design controlled the seven-segment display directly. The chip containes 8192-bit read-only program memory, a 256-bit random-access memory and a decimal arithmetic logic unit as well as control, timing, and output decoders plus drivers for the display. This gives an overall complexity of roughly 8000 transistors. 

Due to a flexible design concept with a programmable ROM some design variations appeared. Compare this IC with the TMS0954 and the later TMS0972. Please find a picture with all three calculator chips here.

A typical calculator built around the TMS0952 family performs the four basic functions +,-,*,: and adds the %-function and a four-key memory. 

Family Members and Usage

Type Calculator Digits
TMS0952 TI-1200, TI-1250 sign + 8
TMS0954 TI-1260 sign + 8
TMS0972 TI-1200, TI-1250 8 or sign + 7
TMS0974 TI-1270 8 or sign + 7
TMS0975 Little Professor (1976) 8

 

Technical Specification

Item Min Typ Max Unit Comments
VSS   0   V   
VDD   +9.0   V   

Housing

The TMS0972 uses a standard DIP-28 package.

Pin Description

Pin IO Function Pin IO Function
1 O Digit driver 6 28 O Digit driver 5
2 O Digit driver 7 (MSD) 27 O Digit driver 4
3 O Digit driver 8 (sign) 26 O Digit driver 3
4 V Negative Voltage VDD 25 O Digit driver 2
5 I Keymatrix input 1 24 O Digit driver 1
6 I Keymatrix input 2 23 O Digit driver 0
7 I Keymatrix input 3 22 R 6k8-VDD
8 I Keymatrix input 4 21 V Ref voltage
9 I Key or power on reset 20 V Common Voltage
10 O Segment driver DP 19 I Clock mode
11 O Segment driver G 18 I Clock input
12 O Segment driver F 17 O Segment driver A
13 O Segment driver E 16 O Segment driver B
14 O Segment driver D 15 O Segment driver C
The Segment drivers A-G and the Decimal point are connected to a display in the pictured way. 

Keyboard Scanmatrix

The keyboards of all calculators based on the TMS0952 family consist of a x/y-matrix connected to six segment-driver outputs and the keymatrix inputs K1 to K4. The Power on reset is usually not connected to a key.

  K1 K2 K3 K4
Seg. DP MC MR M- M+
Seg. F C +/- % :
Seg. E 7 8 9 *
Seg. D 4 5 6 -
Seg. C 1 2 3 +
Seg. B CE 0 . =

Display

Calculators based on the TMS0952 make use of a 9-digit LED-display with common cathode architecture. The TI-1200 uses the LED-stick 233.

If you have additions to the above datasheet please email: joerg@datamath.org.

© Joerg Woerner, February 02, 2001. No reprints without written permission.