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Electronics

Second-generation all-SSI ICs.

ICs are from the Fairchild 9930 DTL logic family, made by Philco in the US and date coded from 1969

9093 Dual JK flipflop
9930 Dual 4-input Expandable NAND
9932 Dual 4-input Expandable buffer NAND
9936 Hex Inverter
9946 Quad 2-input NAND
9962 Triple 3-input NAND

Architecture, Memory & Speed

12 digits displayed with Nixie tubes and a sign indicator lamp. 24-digit results can be accumulated and displayed.

Digit encoding and processing to be determined

Delay line memory is contained in the flat box mounted under the keyboard.

Master clock and digit/full-number times to be determined

Construction

General construction is in keeping with second-generation machines. The case is more elegant with attention to design details but the internal construction is still quite robust. The ICR-412 has a diecast chassis that is separate from the casing and supports the circuit boards and all other components. Most interconnect wiring is handled by a printed circuit backplane and the remaining interconnects are well-made and neatly dressed.

The keyboard uses individual magnetic reed switches.