DATAMATH CALCULATOR MUSEUM
Texas Instruments introduced in 1973 with the TI-4000 Desktop calculator a very compact, yet capable product with a 12-digit display as an upgrade option to the TI-3000 and TI-3500 calculators with 8-digit resp. 10-digit displays. The TI-4000 was the first applications of TIs TMS0200 Building Blocks for Desktop Calculators, a groundbreaking architecture centered around a Data Chip and various Support ICs:
TMS0200 Data Chip Register Processor with four 16-digit Registers and seven Keyboard Scan inputs
TMS0300 ROM Chip 512*13 Bits Instruction Memory with serial interface to Data Chip and 13-digit display and keyboard scanning, up to 4 ROM Chips
TMC0400 ROM/Register Chip - 512*13 Bits Instruction Memory with parallel interface to ROM Chip and two 16-digit Registers
TMS0220 Printer Chip Interface to two-color Drum Printer Mechanism
TMC0250 Printer/Display Chip Interface to Thermal Printer Mechanism and Dot-Matrix Display
The TMS0200 Data Chip requires in a minimum configuration as used in the TI-4000 a TMS0300 ROM Chip for Program Memory and to scan up to 13 digits of the display.
While none of the known products based on the TMS0200 Building Blocks makes fully use of their possibilities like addressing up to 4 ROM chips and up to 16 Register Chips, did the design lay out the architecture of the TMC0500 Building Blocks for Scientific Calculators introduced with the "Slide Rule" calculator SR-50 in January 1974 and leading all the way to the legendary TI Programmable 59 and the amazing SR-60A Prompting Desktop calculator.
The TMC0500 Building Blocks were clearly designed with portable calculators in mind and optimized the necessary real estate of the "calculator brain" dramatically:
TMS0200 - Minimum configuration: 40-pin Data Chip + 40-pin ROM Chip + 16-pin Segment Decoder, optional ROM Expansion with 40-pin ROM/Register Chip
TMC0500 - Minimum configuration: 28-pin Arithmetic Chip + 28-pin Scanning ROM Chip, optional ROM Expansion with piggy-backing a second Scanning ROM Chip and/or additional 8-pin Bare ROM Chips
The similarity between the TMC0500 and TMS0200 architecture allowed even the introduction of additional TMC02xx devices used with products based on the TMC0500 Building Blocks for Scientific and Programmable calculators like the TMC0251 Printer Chip for Thermal Printer Mechanism applied with the Printer Cradle PC-100 for the SR-51, SR-52 and SR-56 calculators.
One pin labeled "PFS" selects on these Chips for Thermal Printers and Dot-Matrix Displays how the 13-bit Instruction Word is provided from the ROM:
TMS0200 Mode (n.c.): IRG A Input for B0 B5 and IRG B Input for B6 B12
TMC0500 Mode (VDD): IRG B Input for B0 B12
The TMC0250 was designed to interface products based on the TMC0500 Building Blocks for Scientific and Programmable calculators with Texas Instruments Thermal Printhead EPN3100 used for example with the PC-100 Printer Cradle and SR-60 Prompting calculator. The EPN3100 comprises a linear array of 100 heaters arranged in 20 characters of five columns, each. A stepper motor moves the thermal paper seven consecutive steps to print characters in a 7*5 dot matrix font but even allows printing graphs by addressing the every dot per print line individually.
The TMC0250 uses the following signals to interface with its electronics:
Twenty Digit Driver Outputs D1 D20 for the 20 characters of five columns, each
Five Column Drivers Outputs C1 C5 for the 5 columns per character
Four Motor Driver Outputs A, /A, B, and /B to advance the thermal printer paper with a Four-Phase stepper motor
The interface between either the TMS0200 Data Chip or TMC501/TMC0501E Arithmetic Chips and the TMC0250 uses a pin-count optimized approach with just 6 or 7 wires:
IRG B for TMC0501/TMC0501E
Arithmetic Chips or IRG A and IRG B for the TMS0200 Data Chip to receive instructions
6-bit Function Data containing to designate one of 64 characters to be printed in each of the 20 positions per line is transmitted serially through the EXT Input
The BUSY Output of the TMC0250 Printer Chip connects with the corresponding input of the TMS0200 Data Chip or TMC0501/TMC0501E Arithmetic Chips to synchronize the components
IDLE, CLK 1 and CLK 2 Inputs are used to synchronize all peripherals connected to the TMC501/TMC0501E Arithmetic Chips with the 16 States of its Instruction Cycle
A special programming of the TMC0250 allows to replace the EPN3100 Thermal Printhead with a 20-character 5*7 LED dot matrix display used with the Prompting calculators SR-60 and SR-60A. While the TMC0251, TMC0254, TMC0255 Printer Chips advances the thermal paper in small increments with a Four-Phase stepper motor, replaces the TMC0253 Display Chip the stepper motor with a simple external shift register cycling through the seven rows of the LED display:
Print first row of 20 characters
Advance stepper motor to next row and print it
Repeat until last row is printed
Pause until next line of characters is loaded
Scan first row of 20 characters
Advance shift register to next row and scan it
Repeat until last row is scanned
Repeat scanning display until next line of characters is loaded
With only a few designs based on the TMS0200 Building Blocks for Desktop Calculators or TMC0500 Building Blocks for Scientific and Programmable Calculators using the optional TMC0250 Printer/Display Chip and Texas Instruments numbering them in a sequential way, we can easily track the individual designs.
QUICK-LINK to TMS0500 Family.
Only certain Desktop and Scientific Calculators introduced between 1973 and 1974 by Texas Instruments, Canon, Olympia and Teal adopted the TMS0200 Architecture, while the TMC0250 Printer/Display Chip found its way into the wildly successful PC-100 Printer Cradle for the SR-51, SR-52, SR-56, TI-58, TI-58C, and TI-59 calculators and the SR-60 Prompting Calculator.
|TMC0251||PC-100, PC-100A, PC-100B, PC-100C||Thermal Dot-Matrix Printer
20 Digits, 5*7 Characters
|TMC0253||SR-60, SR-60A||Dot-Matrix LED Display
20 Digits, 5*7 Characters
|TMC0254||SR-60, SR-60A||Thermal Dot-Matrix Printer
20 Digits, 5*7 Characters
|TMC0255||TI-5230||Thermal Dot-Matrix Printer
20 Digits, 5*7 Characters
|PHI1, PHI2||50||250||300||kHz||Opposite phases|
The TMC0250 was manufactured in a 8 um metal gate PMOS process (metal width = 0.3 mil / 8.0 um, metal spacing = 0.35 mil / 9.0 um, diffusion width = 0.25 mil / 6.0 um, diffusion spacing = 0.35 mil / 9.0 um).
The die size of the TMC0250 is approximately 200 mils * 185 mils / 5.0 mm * 4.7 mm.
The TMC0250 uses a 0.6 wide 40-pin DIP (Dual In-line Package with a 0.1 / 2.54 mm lead pitch).
|1||O||Digit Driver 1 (LSD)||40||V||VGG (-7 V)|
|2||O||Digit Driver 2||39||V||VDD (0 V)|
|3||O||Digit Driver 3||38||I||Clock In 1|
|4||O||Digit Driver 4||37||I||Clock In 2|
|5||O||Digit Driver 5||36||O||Busy with Printer|
|6||O||Digit Driver 6||35||I||Function Data|
|7||O||Digit Driver 7||34||I||IDLE|
|8||O||Digit Driver 8||33||I||Program Format Select|
|9||O||Digit Driver 9||32||I||Instruction word B6-B12/B0-B12|
|10||O||Digit Driver 10||31||O||Stepper Motor Phase /A|
|11||O||Digit Driver 11||30||O||Stepper Motor Phase A/CLK|
|12||O||Digit Driver 12||29||O||Stepper Motor Phase B/IN B|
|13||O||Digit Driver 13||28||O||Stepper Motor Phase /B|
|14||O||Digit Driver 14||27||I||Instruction word B0-B5/n.c.|
|15||O||Digit Driver 15||26||I||Column Driver 5 (left)|
|16||O||Digit Driver 16||25||O||Column Driver 4|
|17||O||Digit Driver 17||24||O||Column Driver 3|
|18||O||Digit Driver 18||23||O||Column Driver 2|
|19||O||Digit Driver 19||22||O||Column Driver 1 (right)|
|20||O||Digit Driver 20 (MSD)||21||V||VSS (+10 V)|
If you have additions to the above datasheet please email: firstname.lastname@example.org.
© Joerg Woerner, March 11, 2021. No reprints
without written permission.