DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
 | Features |
With the TMS0803 Texas Instruments introduced in the year 1974 the successor of the TMS0102 single-chip calculator design. In opposite to the TMS0102 with the discrete segment- and digit-drivers the TMS0803 needs only external digit-drivers to drive the seven-segment LED display. The chip contains 3520-bit read-only program memory (320 words x 11 bits), a 1982-bit random-access memory (44 x 4 bits, flags) and a decimal arithmetic logic unit as well as control, timing, and output decoders with segment drivers for the display. This gives an overall complexity of roughly 5,500 transistors.
Due to a flexible design concept with a programmable ROM some design variations appeared.
A typical calculator built around the TMS0803 family performs the four basic functions +,-,*, : and adds the %-function.
| Family Members and Usage |
| Type | Calculator | Digits | Functions |
| TMS0801 | Sinclair Cambridge | sign + 8 | Constant |
| TMS0803 | TI-1500, TI-2500-II | sign + 8 | % |
| TMS0805 | Sinclair Scientific | sign + 8 | UPN |
| TMS0806 | Exactra 19 | 6 | |
| TMS0807 | Canon LE-85 | sign + 8 | sqr(x), % |
| 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 |
| HousingThe TMS0803 uses a
standard DIP-28 package. |
| Pin Description |
| Pin | IO | Function | Pin | IO | Function |
| 1 | O | Segment driver D | 28 | O | Segment driver C |
| 2 | O | Segment driver E | 27 | O | Segment driver B |
| 3 | O | Segment driver F | 26 | O | Segment driver A |
| 4 | O | Segment driver G | 25 | O | Segment driver DP |
| 5 | n.c. | 24 | O | Digit driver 8 (sign) | |
| 6 | I | Keymatrix input A | 23 | O | Digit driver 7 (MSD) |
| 7 | I | Keymatrix input B | 22 | O | Digit driver 6 |
| 8 | I | Keymatrix input C | 21 | O | Digit driver 5 |
| 9 | V | Common Voltage | 20 | O | Digit driver 4 |
| 10 | I | Keymatrix input D | 19 | O | Digit driver 3 |
| 11 | V | Negative Voltage VDD | 18 | O | Digit driver 2 |
| 12 | V | Negative Voltage VGG | 17 | O | Digit driver 1 |
| 13 | n.c. | 16 | O | Digit driver 0 (LSD) | |
| 14 | O | Clock | 15 | V | Common Voltage |
| The Segment drivers A-G and the Decimal point are connected to a display in the pictured way. |  |
| Keyboard Scanmatrix |
The keyboards of all calculators based on the TMS0803 family consist of a x/y-matrix connected to nine digit-driver outputs and the keymatrix inputs KA and KD.
| KA | KB | KC | KD=KC | |
| D0 | 0 | 9 | ||
| D1 | . | 8 | ||
| D2 | % | 7 | ||
| D3 | : | 6 | ||
| D4 | * | 5 | ||
| D5 | - | 4 | ||
| D6 | + | 3 | ||
| D7 | CE | = | 2 | |
| D8 | C | 1 |
| Display |
Calculators based on the TMS0803 make use of a 9-digit LED-display with common cathode architecture.
If you have additions to the above datasheet please email: joerg@datamath.org.
© Joerg Woerner, February 02, 2001. No reprints
without written permission.
