Early Electronic Calculator Commodore DAC-612 Calculator

Manufacturer:  Commodore Model:  DAC-612 OEM:  Casio Year:  1969 Form:  Desktop Functions:  Basic four, accumulator, rounding Number of Digits:  12 Display Type:  GDI Display: RODAN ELFIN MG-17D Logic Technology:  DIS,SSI,MSI Memory Technology:  MSI-MOS Diodes:  lots and lots Transistors:  39 Principal ICs:  JMOS (µPD100,..) IC Complement: NEC µPD10 (9), NEC µPD11 (4), NEC µPD13C (10), NEC µPD15C (4), NEC µPD101C (9), NEC µPD102C (6), NEC µPD106 (1), NEC µPD110C (10), Hitachi HD3106 (2), Hitachi HD3107 (1), Hitachi HD3112 (1), Philco SC1772 (2) (59 total) Tech. Data Level:  2 Tech. Data Source:  RE Tech. Data Pages:  16 Tech. Data: Schematic (pdf)

As the 1960s ended and headed into the 70s, one branch of popular design headed off into the tacky. With earth tones in glossy plastic and fake-woodgrain mac-tac, this has got to be the ugliest calculator ever produced. Otherwise notable for early use of a 7-segment display, in the form of individual gas-discharge tubes. Note the half-height zero in the display.

Based on info from Rick Bensene, this would be another repackaged Casio calculator. The logic and keyboard are that of the Casio 122 (see Onno's Casio 122) with the 7-segment display replacing the Nixies of the 122. "Model 122" labeling can also be seen on the PCBs.

Notes:

Decimal point position is set by the DP position of the first number entered after clear. Pressing AC (All-Clear) resets the DP position to 0. Division will not adhere to the DP set-point. A constant-mode feature is provided. Entering a number and pressing the multiply or divide key twice fixes that number as multiplier or divisor.

Interior. Note how the two sandwiched logic boards tilt up so they can be removed from the card edge connectors. Also note the empty transistor location on the power supply board. The transistor had failed and had been running rather hot so the replacement has been moved below the board with a new heatsink.	Board A (12H-31 A) top. This is the lower board in the sandwich.	Board A solder side.
Board B (12H-21 B) top. Upper board of the sandwich. The small plug-in board at the top of photo is a replacement for a failed uPD10 IC. It plugs into the IC socket around the middle of board B.	Board B solder side.	Board C (12H-12 C) from the front ..
.. and from the rear.	Individual 7-segment gas-discharge display tubes are not common. They were made briefly near the end of the nixie era but were soon superseded by multi-digit displays such as the Panaplex series.