Characterization of CT5001 Family Single-chip Calculator Circuits

The DCM-50A (PLAYGROUND) supports the Characterization of the CT5001 Family single-chip calculator circuits using the DCM-50A Playground MK6010 Adapter mounted on top of the DCM-50A PG Digit Inverter Frame Carrier and supported by the DCM-50A PG KBD102 Keyboard configured to MK6010 Mode. The voltage selector jumper on the MK6010 Adapter must be set to the appropriate voltage. The optional DCM-50A Playground Digilent I/O Extender supports Characterization and Reverse-engineering of CT5001 Family single-chip calculator circuits.

CT5001

Device-under-Test:

Keyboard: The Unitrex 1200 makes use of a keyboard assembly with 17 spring-loaded plastic keys pushing two fingers of stamped sheet-metal pieces soldered perpendicular on a single-sided phenolic PCB together. The 10 number keys are connected with a diode matrix to the key inputs KN1 to KN4 (Numbers) of the CT5001 while the 7 function keys are connected to its discrete key inputs. The 4-position sliding switch for the Decimal Point selection is connected with a diode matrix to the DP1 and DP2 inputs of the CT5001.

Keyboard Matrix of the Unitrex 1200 (Type 27, Rev. 4C):

Display: The Unitrex 1200 makes use of a USHIO U-BR-12400ES Planar Neon Gas Discharge Display (Panaplex-style) connected with two Kyodo KH-6225 Digit Driver Modules and 12 high-voltage capacitors as level shifters to the twelve Digit Outputs D1 to D12 of the CT5001 and one Kyodo KH-6259 Segment Driver Module connected to the Segment Outputs SA to SG and SDP of the CT5001. The display is operated with approximately +180 Volts. An additional discrete orange miniature gas-discharge lamp is used as minus sign for negative numbers and connected with a transistor to the Sign output of the CT5001.

Display Layout:

Display Fonts:

Display scanning: The CT5001 single-chip calculator circuit is manufactured in a PMOS process and its Digit Scanning Outputs are high-side PMOS transistors. For easy interfacing to low-voltage VFDs (Vacuum Fluorescent Displays) or high-voltage gas-discharge displays, an activated digit corresponds to a logical 0 or open output. All other, non-activated digits have the PMOS transistors turned on. Please notice that the the DCM-50A PG Digit Inverter Frame Carrier used to characterize the CT5001 chip is inverting the Digit Outputs D1 to D12 and we labeled them therefore /D1 to /D12 on the graphs.

Display scanning is performed in D1 → D12 direction at a rate of about 480 Hz:

CT5002

Device-under-Test:

Keyboard: The Caltronic 812 makes use of a Klixon™ 1KS116 keyboard assembly consisting of the "Basic 1KS" keyboard array with 17 snap-action Klixon discs mounted on a printed circuit board for the interconnections of the switches to the external calculator circuit and a stainless steel mounting frame and the molded keytops. In addition, the keyboard assembly integrates two two-position slide switches: one for selecting the decimal-point position and the other for switching the calculator power on and off. The 10 number keys are connected with a diode matrix to the key inputs KN1 to KN4 (Numbers) of the CT5002 while the 7 function keys are connected to its discrete key inputs. The 2-position sliding switch for the Decimal Point selection is connected with a diode matrix to the DP1 input of the CT5002 with the DP2 input connected to log.0 (V_SS).

Keyboard Matrix of the Caltronic 812:

Display: The Caltronic 812 makes use of a 9-digit LED display assembly composed of three Litronix DL-33 3-digit seven-segment LED displays housed in 12-pin packages and soldered onto the double-sided Display-PCB. In addition to the numeric displays, the Display-PCB incorporates an indicator LEDs for low-battery status. The Display-PCB is connected to the Main-PCB and Keyboard Assembly of the Caltronic 812 with 22 hand-soldered connections directly to one side of a two-row connector. The Common Cathodes D1 to D8 of the LED display are connected with two SN75492 Digit Drivers to the Digit Outputs D1 to D8 of the CT5002 while D9 is driven with its Sign Output. The A to G segments and Decimal Point (Anodes) of the LED display are driven directly from the Segment Outputs SA to SG and SDP of the CT5002 with eight discrete 430 Ohm resistors to limit the maximum peak current. The indicator for a low battery is controlled by the power supply circuitry of the calculator.

Display Layout:

Display Fonts:

Display scanning: The CT5002 single-chip calculator circuit is manufactured in a PMOS process and its Digit Scanning Outputs are high-side PMOS transistors. For easy interfacing to LED displays, an activated digit corresponds to a logical 1 or closed output. All other, non-activated digits have the PMOS transistors turned off.

Display scanning is performed in D1 → D12 direction at a rate of about 380 Hz: