DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
 | Features |
With the TMC05xx building blocks Texas Instruments created a novel architecture for scalable scientific calculators. The architecture uses minimum a 2 chip design with the Arithmetic chip TMC0501 and the SCOM (scanning read only memory) but was expandable to a maximum of 8 SCOM's, additional RAM as program memory for programmable calculators, additional RAM for general purpose registers and even a chip driving a printer. Most scientific and programmable calculators from Texas Instruments between the years 1974 and 1982 (SR-50..TI-59) use these chips.
The TMC0521 Scanning Read Only Memory SCOM contains 1k*13 instruction memory and 16*16 digits constants.
Additional functions of the TMC0521 include scanning of the display digit driver outputs and the keyboard.
| Usage |
SR-50, SR-50A
Note: The early ROM-code TMC0521-2 and -4 is less accurate and was replaced July, 1974 with the -5 code. Please find the comparison in the Calculator forensics.
| Technical Specification |
| Item | Min | Typ | Max | Unit | Comments |
| VSS | 0 | V | |||
| VDD | -10.5 | -10.0 | -9.5 | V | |
| VGG | -16.3 | -15.8 | -15.3 | V | |
| PHI1, PHI2 | 225 | 230 | kHz | Opposite phases |
| HousingThe TMC0521 uses a
standard DIP-28 package. |
| Pin Description |
| Pin | IO | Function | Pin | IO | Function |
| 1 | O | Digit driver 14 | 28 | O | Digit driver 14 |
| 2 | V | Negative Voltage VGG | 27 | O | Digit driver 13 (OVER) |
| 3 | V | Negative Voltage VDD | 26 | O | Digit driver 12 (E-MSD) |
| 4 | IO | SCOM Interface D0 | 25 | O | Digit driver 11 |
| 5 | IO | SCOM Interface D1 | 24 | O | Digit driver 10 |
| 6 | IO | SCOM Interface D2 | 23 | O | Digit driver 9 |
| 7 | IO | SCOM Interface D3 | 22 | O | Digit driver 8 |
| 8 | O | Instruction words | 21 | O | Digit driver 7 |
| 9 | I | Calculating status | 20 | O | Digit driver 6 |
| 10 | I | External access | 19 | O | Digit driver 5 |
| 11 | I | Clock Input 2 | 18 | O | Digit driver 4 |
| 12 | I | Clock Input 1 | 17 | O | Digit driver 3 (M-LSD) |
| 13 | V | Common Voltage | 16 | O | Digit driver 2 (E-MSD) |
| 14 | O | Digit driver 0 | 15 | O | Digit driver 1 (E-LSD) |
| Keyboard Scanmatrix |
The keyboards of all calculators based on the TMC0501 Arithmetic chip consist of a x/y-matrix connected to the SCOM digit driver outputs and the TMC0501 keymatrix inputs.
| KN | KO | KP | KQ | KR | KS | KT | |
| D0 | |||||||
| D1 | 1 | = | C | log | eX | SUM | |
| D2 | 2 | - | hyp | ||||
| D3 | 3 | + | . | X2 | D/R | ||
| D4 | 4 | arc | lnX | ||||
| D5 | 5 | ||||||
| D6 | 6 | : | CE | 1/X | cos | STO | |
| D7 | 7 | * | +/- | sin | pi | ||
| D8 | 8 | RCL | |||||
| D9 | 9 | Y#Y | |||||
| D10 | 0 | XsqrY | |||||
| D11 | XY | ||||||
| D12 | sqrX | ||||||
| D13 | EE | X! | tan |
Comments: The R-D switch is detected with a diode between D14 - KT.
If you have additions to the above datasheet please email: joerg@datamath.org.
© Joerg Woerner, February 02, 2001. No reprints
without written permission.
