CS-20A Technology
Electronics
The logical architecture is unusual in that there is no specific memory element such as magnetic core, delay line or similar. This suggests a design based on the electronic implementation of mechanical calculators, similar to the ANITA machines.
Architecture, Memory & Speed
- 14 displayed digits, one sign indicator by special Nixie.
- Digit encoding and processing to be determined but is likely to be counter-based.
- No specific memory element
- @@kHz master clock, @@mS core cycle, @@mS full-number time
Construction
The machine is constructed on double-sided phenolic circuit boards. Fifteen boards have a single Nixie tube and appear to have a 4-bit register and decoder/drivers for the Nixie to show the value in that 4-bit register. Many of these boards have additional logic. Three boards have logic but no Nixies and a larger pair of boards across the full width of the rear are bolted together into a sandwich marked “Program” and “AP”. The program board holds a large diode array and this may be a form of read-only memory that holds the logical sequencing for each calculator operation.
The boards appear to be early versions and quite a number have jumper wires that modify the printed pattern.
The power supply is transformer based with simple linear regulation of logic voltages. Heavy bus wires distribute power across the edge connector backplane but there are relatively few bypass capacitors across the boards.
The mechanical construction is elaborate with a complex die-cast chassis and a heavy die-cast keyboard plate. The main assemblies are build in a modular fashion and all attach to the chassis with many screws and bolts. The edge connector backplane is hand wired and nicely dressed.