DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Characterization of Single-chip Calculator Circuits - TMS1000 Family
The DCM-50A Platform supports the Characterization of 28-pin TMS1000 Devices in its right-most TMS1000 Textool Test Socket with the voltages VSS set to 9.5V and VDD/VGG set to -5.5V, accordingly for devices of the 15V Series. The later 9V Series requires different voltage settings with VSS set to 5.5V and VDD/VGG set to -3.5V.
Device-under-Test:
| • Package Markings Top:
REGENCY 501-374, BSP 7731 • Package Markings Bottom: ⚫DP1116BS, SINGAPORE • Donor Product: Radio Scanner Regency ACT-T16K, October 1977 |
Keyboard: The Regency ACT-T16K makes use of a keyboard with touch-sensitive switches arranged in a 9*4 matrix with the rows connected to the R0-R8 Outputs (Display Scan) and the columns connected to the K1-K8 Inputs (Keyboard Scan) of the TMS1116NL single-chip calculator circuit. The Squelch sliding switch is connected between the R9 Output and K2 Input.
Keyboard Matrix of the Regency ACT-T16K:
| K1 | K2 | K4 | K8 | |
| R0 (D1) | SS | 1 | 0 | [--] |
| R1 (D2) | SC | 3 | 2 | |
| R2 (D3) | MA | 5 | 4 | CL |
| R3 (D4) | SP | 7 | 6 | . |
| R4 (D5) | PR | 9 | 8 | |
| R5 (D6) | C4 | C3 | C2 | C1 |
| R6 (D7) | C8 | C7 | C6 | C5 |
| R7 (D8) | C12 | C11 | C10 | C9 |
| R8 (D9) | C16 | C15 | C14 | C13 |
| R9 (D10) | [--] | [SQUL] | ||
| R10 |
Display: The
Regency ACT-T16K makes use makes use of National Semiconductor NSA578
Seven-Digit Calculator Numeric Seven-Segment LED Display module controlled with
2 additional
SN75492-style digit drivers from the
corresponding Output pins R0 to R6 and the segments SA to SDP driven directly
from the TMS1116 chip. The 16 discrete Channel LEDs are connected through Digit
Drivers to R7 and R8, leaving the Search LED on R9, segment DP.
Display Layout:
| National Semiconductor NSA578 |
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The Output Decoder PLA of the TMS1116NL is programmed for 7-Segment displays with the following Output Assignments:
| TMS1116 Pin | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 |
| TMS1116 Port | O0 | O1 | O2 | O3 | O4 | O5 | O6 | O7 |
| Segment | DP | A | B | C | D | E | F | G |
| The Segment drivers A-G and DP (Decimal Point) are connected to the National Semiconductor NSA578 display in the pictured way. |  |
Display Fonts:
| Type | Product | Number Fonts | Decimal Separator |
Error |
| TMS1116NL | ACT-16K |  |
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Scanning: Display and keyboard scanning is performed in R0 → R9 direction at a rate of about
150 Hz followed by an RX State to display the Decimal Point. R9 State is
stretched to read in signals not generated by the keyboard through a Quad 2-Line
to 1-Line Data Selector connected to the four K1-K8 Inputs (Keyboard Scan) of
the TMS1116NL:
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• Instruction Cycle Time
(ICT) = 6 Clocks = 0.02 ms @ CK=300 kHz • Leading Digit Blanking Time = 4 ICT = 0.08 ms • Active Digit Time R0 → R8 = 20 ICT = 0.40 ms • Active Digit Time R9 = 64 ICT = 1.28 ms • Active Digit Time RX = 20 ICT = 0.40 ms • Trailing Digit Blanking = 1 ICT = 0.02 ms • Blank State R9 → R0 = 22 ICT = 0.49 ms • Display Cycle Time = 341 ICT = 6.82 ms |
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, September 4, 2023. No reprints without written permission.