DATAMATH CALCULATOR MUSEUM
Texas Instruments announced on September 16, 1975 with the SR-52 their first Keystroke Programmable Handheld Calculator based on the TMC0500 Building Blocks for Scientific and Programmable Calculators introduced already in January 1974 with the SR-50 Slide Rule calculator. While the SR-50 used only the minimum configuration of this groundbreaking architecture combining the TMC0501 Arithmetic Chip and one TMC0521 SCOM (Scanning Read-Only Memory) Chip with the necessary display drivers for its 14-digit LED display plus power supply and clock generation, went the SR-52 a step ahead and made full use of the TMC0500 Building Blocks. A closer look at the PCB (printed circuit board) of the SR-52 reveals a total of seven PMOS (P-channel Metaloxide Semiconductor) chips:
TMC0501: Arithmetic Chip Register Processor with five 16-digit Registers and segment decoder/driver
TMC0524: TMC0520 Scanning and Read-Only Memory Chip 1,024*13 Bits Instruction Memory with serial interface to Arithmetic Chip, 16 Constants with 16 digits, each, two 16-digit Registers and 16-digit display scanning
TMC0562, TMC0563: Two TMC0560 Bare Read-Only Memory Chips 1,024*13 Bits Instruction Memory with serial interface to Arithmetic Chip, each for a combined 3,072*13 Bits Instruction Memory
TMC0595: Magnetic I/O Chip Four channel interface for magnetic card reader to save and load programs with up to 224 steps
TMC0599*2: Two Multi-Register Chips 240*8 Bits Random Access Memory with 4-bit I/O Bus to Arithmetic Chip, stores 240 program steps or 30 numbers of 16 digits, each
Texas Instruments introduced together with the calculator a matching "Printer Cradle" PC-100 with an integrated alphanumerical printer capable to print up to 20 characters per line at a speed of three lines per second on a 2.5 inch wide thermal paper. The SR-52 calculator connects to the PC-100 printer cradle with a 12-pin connector accessible through its battery compartment and featuring all TMC0500 signals necessary to communicate to two additional PMOS chips hosted on the PC-100 PCB:
TMC0561, TMC0569: Two
TMC0560 Bare Read-Only Memory Chips 1,024*13
Bits Instruction Memory with serial interface to Arithmetic Chip for all commands responsible for printing and tracing
TMC0251: TMC0250 Printer/Display Chip Interface to Thermal Printer Mechanism
The SR-60 Prompting Desktop calculator introduced in 1976 took the architecture of the SR-52 even a step further and integrated an alphanumeric display and keyboard with even more Instruction and Data/program memory into a large but elegant housing.
The TMC0596 Magnetic I/O Chip used with the SR-60 and SR-60A Prompting Desktop calculators provides the interface between the four-track magnetic card read/write mechanism and the TMC0501 Arithmetic Chip. Communication between the two chips is realized with multiple means:
IDLE, PHI 1 and PHI 2
Signals are used to synchronize all peripherals connected to the
TMC0501/TMC0501E Arithmetic Chips with the 16 States of its Instruction Cycle
EXT Output indicates that the TMC0501/TMC0501E Arithmetic Chips are addressing external memories/registers
IRG Input to receive the 13-bit Instruction Words from the Instruction Memory
The TMC0596 Magnetic I/O Chip also conditions the signals to and from the magnetic card read/write mechanism (e.g. motor, card sensor input, channel 1-4) to make them compatible with PMOS logic levels.
The card speed of the SR-60 is set at 3.7 IPS (inches per second), the calculator will operate at a card speed of 3.3 IPS to 4.1 IPS.
QUICK-LINK to TMS0500 Family.
Reference Voltage -5.1 V
|TMC0596 Rev A||SR-60||March 1985||Reference Voltage -5.1 V|
|TMC0596 Rev B||SR-60, SR-60A||July 1975||Reference Voltage -3.3 V|
|PHI1, PHI2||225||230||kHz||Opposite phases|
The TMC0595 uses a standard 0.4 wide 22-pin DIP (Dual In-line Package with a 0.1 / 2.54 mm lead pitch).
|1||A||R/W Track 2||22||A||R/W Track 3|
|2||A||Capacitor Track 2||21||A||Capacitor Track 3|
|3||A||R/W Track 1||20||A||R/WTrack 4|
|4||A||Capacitor Track 1||19||A||Capacitor Track 4|
|5||V||Common Voltage||18||V||Reference Voltage|
|6||O||Instruction words||17||V||Common Voltage|
|7||I||Calculating status||16||I||External access|
|8||O||Keyboard emulation||15||I||Clock Input 2|
|9||O||Motor on/off||14||I||Clock Input 1|
|10||I||Card Sensing Input||13||V||Negative Voltage VDD|
|11||O||Lamp||12||V||Negative Voltage VGG|
If you have additions to the above datasheet please email: firstname.lastname@example.org.
© Joerg Woerner, March 19, 2021. No reprints
without written permission.