Texas Instruments TMC0980


Texas Instruments announced on September 17, 1971 with the TMS1802NC the first commercially available standard calculator building block for a basic four-function calculator on a chip. The TMS1802NC, later renamed to TMS0102, included all control, timing, and output decoders for the display but lacked its drivers. It took another four years until Texas Instruments introduced with the TMS0952 a "real" single-chip design for a more capable basic calculator like the TI-1200.

The TMC0980 family of single-chip calculator circuits was introduced in June 1976 with the two scientific calculators SR-40/TI-30 and the financial calculator Business Analyst of the Majestic product line. The TMC0980 is an extension of the TMS1000 Microcomputer family and allows for highly cost optimized calculators with up to 40 keys and a 9-digit LED Display powered by a 9V battery. Additional cost savings could be achieved by replacing a conventional [ON-OFF] switch with a simple push-button [ON] key. The TMC0980 chip includes 18,432 Bits Read-Only Memory (ROM, 2k*9 Bits) and 576 Bits Random-Access Memory (RAM, 9 Registers * 16 digits), a 4-bit Arithmetic unit, a programmable PLA for segment decoding and both segment and digit drivers for a 9-digit LED Display.

Later calculators in the Majestic line like the TI-55, TI Programmable 57, and The MBA used with the TMC1500 family a much more capable calculator brain doubling the RAM capacity and supporting 12-digit displays.  

Due to a flexible design concept with both programmable ROM and segment decoder some design variations of the TMC0980 were introduced and Texas Instruments expanded the product family before finally converting the design with the TP0320 from a 9V metal gate PMOS process to a 3V metal gate CMOS process:

TMC1980: 9-digit, 7-segment VF-Display, 28-pin Package (Dataman)
TMC0260: 11-digit, 7-segment VF-Display, Thermal Printer Interface, 40-pin Package (TI-5040)
TMC0270: 9-digit, 14-segment VF-Display, 40-pin Package (Speak & Spell)

Family Members and Applications

Type Calculator/Product Application Comments
TMC0980/CD9801 Goulds Pumpulator Custom Design ROM code CD9801
TMC0980/MP6100 Ideal Electronic Detective Toy ROM code MP6100
TMC0980/MP6101B Parker Brothers Stop Thief Toy ROM code MP6101B
TMC0981 SR-40, TI-15, TI-30, 30/super, SR-35NC, Silca 48, Studio 29, TI-40, TI professional Scientific 8 (5+2) digits
TMC0982 Business Analyst, Business Analyst I, Money Manager, TI-31, TI-41 Financial 8 (5+2) digits
TMC0983/ZA0675 TI Programmer HEX calculator ROM code ZA0675
TMC0984 TI-33 Scientific 3 Mem., 8 (5+2) digits
TMC0985 OEM Scientific No AOS, 8 (5+2) digits

Note: Learn more about the MOS Numbering System used by Texas Instruments' early MOS Chips.


  Description Comments
Architecture Single-chip Calculator Scientific, Financial
Category Digit Processor 4-bit digits
Related TMC1980
7-segment VF-Display
7-segment VF-Display, Printer
14-segment VF-Display
ROM Size 18,432 Bits 2048 Words * 9 Bits
RAM Size 576 Bits 9 Registers * 16 digits
Outputs 9 Digits, 8 Segments Integrated Digit and Segment Drivers
Inputs 5 Keyboard
1 Clock Mode
Segment to Keyboard Scan-Matrix

Technical Specifications

Item Min Typ Max Unit Comments
VSS   0   V   
VDD   -9.0   V   
CK  250 350 450 kHz  Internal oscillator


The TMC0980 was manufactured in a 6 um metal gate PMOS process (metal width = 0.25 mil / 6.0 um, metal spacing = 0.25 mil / 6.0 um, diffusion width = 0.15 mil / 4.0 um, diffusion spacing = 0.30 mil / 8.0 um).

The die size of the TMC0980 is approximately 180 mils * 190 mils / 4.5 mm * 4.9 mm.


The TMC0980 uses a 0.4 wide 28-pin SPDIP (Shrink Plastic Dual In-line Package with a 0.07 / 1.778 mm lead pitch).

Pin Configuration

Pin IO Function Pin IO Function
1 O Digit driver 7 28 O Digit driver 6
2 O Digit driver 8 (MSD) 27 O Digit driver 5
3 O Digit driver 9 (sign) 26 O Digit driver 4
4 V Substrate (VSS) 25 O Digit driver 3
5 V Negative Voltage VDD 24 O Digit driver 2
6 I Keymatrix input 1 23 O Digit driver 1 (LSD)
7 I Keymatrix input 2 22   n.c.
8 I Keymatrix input 3 21   n.c.
9 I Keymatrix input 4 20 V Positive Voltage VSS
10 I Keymatrix input 8 19 I Oscillator Mode
11 O Segment driver DP 18 O Segment driver C
12 O Segment driver B 17 O Segment driver E
13 O Segment driver G 16 O Segment driver F
14 O Segment driver D 15 O Segment driver A
The Segment drivers A-G and DP (Decimal Point) are connected to the display in the pictured way. 

Keyboard Scan-Matrix

The keyboards of all calculators based on the TMC0980 family consist of an x/y-matrix connected to up to seven segment outputs with the top row ([ON] key) connected to VSS and the keymatrix inputs K1, K2, K3, K4, and K8. 

Example for the TI-30 with TMC0981:

  K4 K2 K3 K1 K8
VSS 1/x x2 x OFF ON
Seg. B INV sin cos tan DRG
Seg. C K EE log lnx yX
Seg. D PI % ( ) ÷
Seg. E STO 7 8 9 ×
Seg. F RCL 4 5 6
Seg. G SUM 1 2 3 +
Seg. DP EXC 0 . +/− =


Calculators based on the TMC0980 make use of 9-digit LED Displays with common cathode architecture. 

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If you have additions to the above datasheet please email:

Sean Riddle and Joerg Woerner, January 9, 2021. No reprints without written permission.