Casio 122 calculator
This is a very nice desk calculator from the late sixties.
It has a multiplexed 12-digit nixie tube display.
On the overview photograph below you can see the calculator with the top
taken off and turned upside down.
The top part (on the left) contains the display board and keyboard assembly.
The bottom part (on the right) contains the power supply and the two logic
boards, that are mounted as a sandwich.
Calculator opened up.
Topmost logic board.
On the right, the topmost logic board is shown.
It contains a large number of IC's, in
DIL-14 case, and one in a DIL-24 case.
These are specific Japanese types, by Hitachi and NEC.
The are mostly SSI (standard Scale integration, i.e. logic chips that
contain gates and flipflops), but the DIL-24 IC is an serial BCD (Binary
Coded Decimal) adder (Hitachi HD3112).
The technology used is MOS, it is called "JMOS" (Japanese MOS)
by some. I learned some about these chips on
calculator site at the University of British Columbia.
Even a child can use it...
I got this calculator from a radio collector.
When I tried it, it was just fine.
It works good and it is quite undamaged.
A pearl on my desk (for accounting only, though, no scientific stuff).
And easy, even a child can use it, as you can see...