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Texas Instruments TMS0970A, TMS0970AS, TMC0900A, TMC0900AS

Features

Texas Instruments introduced the TMS0970 in March 1976 as pin-compatible and cost-optimized upgrade of the TMS0950, effectively dropping 4 resistors and 1 capacitor from the printed circuit board (PCB) and shrinking its silicon area by almost 30%.

Based on the Digit Processor architecture of the TMS1000 Microcomputer and featuring a large program memory with 1,024 Bytes ROM (Read-Only Memory) capacity and a flexible RAM (Random-Access Memory) with 256 Bits organized in 4 files of 16-digits, each plus integrated segment and digit drivers for an 8-digit LED display and everything powered by a small 9V alkaline battery, the TMS0970 found its way into many products. Most successful was certainly the Little Professor introduced in 1976 but Texas Instruments sold a basic design (TMS0972, four-banger with 4-key memory) to third party manufactures, too and it proofed to be very successful with OEMs in Hong Kong around 1977 and 1978 with what we call here in the Datamath Calculator Museum "Far East Generic Design I, Design II, and Design III".

With millions and millions of the TMS1000 Microcomputer deployed in hundreds of customer designs by 1977 and the TMS0970 basically a very cost-effective way to implement electronic consumer products, Texas Instruments started marketing the design as TMC0900 (C as in Customer) and the chip found its way into various electronic games and toys.

With calculator prices dropping in 1977 significantly below the $10 mark, Texas Instruments introduced in 1977 both a cost-optimized version of the TMS0970/TMC0900 in a 28-pin Shrink Plastic Dual In-line Package and a design variation replacing a conventional [ON-OFF] switch with a simple push-button [ON] key as TMC1990.

Family Members and Applications

Type Calculators Digits
TMS0972 TI-1200, TI-1250 8 or sign + 7
TMS0974/ZA0355 TI-1270, Western Auto Citation 8 or sign + 7
TMS0975/ZA0356 Little Professor (1976) 8
TMC0904 Milton Bradley COMP IV 0 + 10 LEDs
TMC0905 Parker Brothers Code Name:Sector 6 + 4 LEDs
TMC0907/ZA0379 Wiz-A-Tron (1977), MATH MAGIC 8

 

Architecture

  Description Comments
Architecture Single-chip Calculator Basic, Educational, Toys
Category Digit Processor 4-bit digits
Related TMS1000
TMS0950
Generic design
Original design
ROM Size 8,192 Bits 1024 Words * 8 Bits
RAM Size 256 Bits 64 Digits
Outputs 9 Digits, 8 Segments Integrated Digit and Segment Drivers
Inputs 4 Keyboard
1 Oscillator Mode
1 Reset
Segments to Keyboard Scan-Matrix

Technical Specifications

Item Min Typ Max Unit Comments
VSS   0   V   
VDD   -9.0   V   
CK  200 250 300 kHz  Internal oscillator

Technology

The TMS0970A and TMC0900A were manufactured in a 8.0 um metal gate PMOS process (metal width = 0.30 mil / 8.0 um, metal spacing = 0.30 mil / 8.0 um, diffusion width = 0.25 mil / 6.0 um, diffusion spacing = 0.30 mil / 8.0 um).

The die sizes of the TMS0970A and TMC0900A are approximately 190 mils * 160 mils / 4.8 mm * 4.0 mm.

The TMS0970AS and TMC0900AS were manufactured in a 6.0 um metal gate PMOS process (metal width = 0.25 mil / 6.0 um, metal spacing = 0.25 mil / 6.0 um, diffusion width = 0.20 mil / 5.0 um, diffusion spacing = 0.20 mil / 5.0 um).

The die sizes of the TMS0970A and TMC0900A are approximately 170 mils * 145 mils / 4.3 mm * 3.6 mm.

Packaging

The TMS0970A(S) and TMC0900A(S) are using either a 0.6 wide 28-pin DIP (Plastic Dual In-line Package with a 0.1 / 2.54 mm lead pitch)
or a 0.4 wide 28-pin SPDIP (Shrink Plastic Dual In-line Package with a 0.07 / 1.778 mm lead pitch).
Please notice the different pinouts of the two packages.

Pin Configuration

DIP-28

Pin IO Function Pin IO Function
1 O Digit driver 7 28 O Digit driver 6
2 O Digit driver 8 (leftmost) 27 O Digit driver 5
3 O Digit driver 9 (n.c.) 26 O Digit driver 4
4 V Negative Voltage VDD 25 O Digit driver 3
5 I Keymatrix input 1 24 O Digit driver 2
6 I Keymatrix input 2 23 O Digit driver 1 (rightmost)
7 I Keymatrix input 3 22   n.c.
8 I Keymatrix input 4 21   n.c.
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


SPDIP-28

Pin IO Function Pin IO Function
1 O Digit driver 7 28 O Digit driver 6
2 O Digit driver 8 (leftmost) 27 O Digit driver 5
3 O Digit driver 9 (n.c.) 26 O Digit driver 4
4 V Negative Voltage VDD 25 O Digit driver 3
5 I Keymatrix input 1 24 O Digit driver 2
6 I Keymatrix input 2 23   n.c.
7 I Keymatrix input 3 22   n.c.
8 I Keymatrix input 4 21 O Digit driver 1 (rightmost)
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 O Segment driver A
12 O Segment driver F 17 O Segment driver B
13 O Segment driver E 16 O Segment driver C
14   n.c. 15 O Segment driver D
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 TMS0972(A) 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.

Example for the TI-1250 with TMS0972: 

  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 TMS0970(A) and TMC0900 make typically use of a 8-digit LED-display with common cathode architecture. The TI-1200/TI-1250 uses the LED-stick 233 without the leading digit populated.

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.