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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 based on the TMS1000 family. 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 integrates 8192-bit read-only program memory (ROM), a 256-bit random-access memory (RAM) and a decimal arithmetic logic unit as well as control, timing, and output decoders plus drivers for the display. This adds up to 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 pictures 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, the later TMC0980 allowed for both scientific and financial calculators with up to 40 keys. 

Family Members and Applications

Type Calculators 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
TMC0904 Milton Bradley COMP IV 0 + 10 LEDs
TMC0905 Parker Brothers Code Name:Sector 6 + 4 LEDs
TMC0907 Wiz-A-Tron (1977) 8

 

Technical Specifications

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

Packaging

The TMS0952 uses a standard 0.6” wide 28-pin DIP (Dual In-line Package with a 0.1” / 2.54 mm lead pitch).

Pin Configuration

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 Scan-Matrix

The keyboards of all calculators based on the TMS0952 family consist of an 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.

horizontal rule

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

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