DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Datamath Calculator Museum DCM-50A Playground 2-Phase Clock Module
| Date of introduction: | October 2, 2025 | Display technology: | n.a. |
| New price: | Display size: | n.a. | |
| Size: | 2.4" x 2.6" x 1.00" 61 x 66 x 25 mm3 |
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| Weight: | 1.0 ounces, 28 grams | Serial No: | 0001 |
| Batteries: | n.a. | Date of manufacture: | mth 11 year 2025 |
| AC-Adapter: | n.a. | Origin of manufacture: | USA |
| Precision: | Integrated circuits: | CD4093, CD40106, CD40175, SN75369 | |
| Memories: | |||
| Program steps: | Courtesy of: | Joerg Woerner |
When
Texas Instruments introduced with the TMS0100
their first generation single-chip calculator circuit, it didn't include the
oscillator for its internal electronics and the Datamath Calculator Museum
DCM-50A
Platform features consequently an astable mutlivibrator with 250 kHz to
operate the chip. Most calculator chipsets and some early single-chip calculator
circuits are using external 2-Phase clock signals for the implementation of
dynamic logic and their shift-register based registers, rendering them
incompatible with our DCM-50A Platform.
On our mission to Characterize and Reverse-Engineer not only calculator chips manufactured by Texas Instruments, but branching out to offerings from their competitors in the 1970s, namely AMI, Cal-Tex, Commodore/MOS Technology, Electronic Arrays, Frontier, General Instrument, Hitachi, Litronix, Matsushita, Mitsubishi, Mostek, National Semiconductor, NEC, Omron, RFT, Rockwell, Sharp, Toshiba, and Western Digital, we developed the DCM-50A (PLAYGROUND) with its modular approach.
To
support calculator chips using 2-Phase clock signals, we developed a small printed circuit board (PCB)
that can be used with the DCM-50A Platform. The DCM-50A Playground 2-Phase Clock
Module allows the generation of two non-overlapping clock signals with three
different timing patterns, an adjustable internally or externally provided
frequency and adjustable amplitude (VGG from DCM-50A or VPP = -12 V).
Additionally, the PCB is providing Reset signals of positive and negative logic
during power-up or a Reset-button. The DCM-50A Playground 2-Phase Clock Module
plugs with three Jumper-Headers over the TMS1000 ZIF-Socket and connects to the
calculator circuits under test through a conveniently located Pin-Header.
The
three different Clock Timing Patterns generated with the DCM-50A Playground
2-Phase Clock Module vary the width of the Clock 1 (CK1) between 1 and 3 periods
of the internal or external clock frequency (CK) while keeping the width of the
Clock 2 (CK2) signal constant at 1 period of CK.
The schematics and layout of the DCM-50A Playground 2-Phase Clock Module are providing accordingly:
| • VSS, VDD and VGG access from
Jumper-Header J23 and J26, respectively • Pin-Header to recreate J23 and J26 • DC/DC Converter to generate VPP voltage (-12 V) vor high-voltage calculator chips • LED to signal the VPP voltage • Pin-Header to access VSS, BRES, /BRES, GND (VDD), CKE, BCK1, BCK2 and VPP and Test Points for CK1 and CK2 • Pin-Header to select Internal or External Clock • Pin-Header to select Negative Level of BRES, /BRES, BCK1 and BCK2 (L.V. = VGG, H.V. = VPP) • 3-position Rotary Switch (blue) to select Clock Pattern • Potentiometer to adjust the Clock Width 3 us - 20 us • Red Reset Button |
2-Phase Clock Module - Frontier FR1001 DUT: CK WIDTH: 10 us, CK1 MULTIPLIER: 1 (CK1 Frequency = 25 kHz); VOLTAGE: L.V. (VGG); BCK1--CK1, BCK2--CK2, /BRES--CL.
Please notice that the DCM-50A Playground Clock Recovery Module needs to be plugged over the TMS1000 ZIF-Socket into the three Jumper-Headers J21, J23 and J26 on the DCM-50A Platform.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, April 12, 2026. No reprints without written permission.