MICROFORUM

Does anyone have information on how the A4350 calculator circuit is connected? It is said to have been cloned by the Soviets and used in their calculators.

The A4350 circuit was manufactured by Rockwell. It was imported to Eastern Europe through the Polish company Unitra. Tesla Bratislava used this circuit in OKU104 calculators. I drew the wiring diagram of the OKU104 and OKU107 calculators in 2015 and you can download them from the website http://www.jplabs.co.uk/cz/cs_doc.html.
I do not know the Soviet version of this circuit, nor have I ever encountered it.

I have several OKU calculators, but none of them work. They mostly have non-functioning buttons or broken wires to the keyboard board. I don't know where to reconnect the wires. So I thought of soldering the calculator circuit, making a new board and improving the calculator, adding memory and making it programmable using classic circuits. I was surprised by the power supply of the calculator. What exactly is the level of log.0 and log. 1 ?

that interests me: How can a calculator circuit that can perform 4 basic operations be turned into a programmable calculator? Using a microcomputer? It makes no sense with a microcomputer if the microcomputer itself replaces the calculator circuit. I can't imagine this expansion without a microcomputer with classic circuits.

oldcomp wrote: ↑Mon Jul 17, 2023 8:31 amWhat exactly is the level of log.0 and log. 1 ?

The logic levels of the A4350 circuit are inverse compared to log. levels for the CMOS-4000 line circuit.

so if i understand correctly i can use CMOS 4000 series for A4350 circuit?

yes, but you have to adjust the logic levels. As far as expansion is concerned, rather than making the A4350 circuit into a programmable calculator, it is more appropriate to use additional logic to extend the functions. The A4350 circuit has only 4 basic functions.