I've been busy with the log(x) function. It works quite nice, see CALC_6.TXT. The simulator counts the cycles between key presses, the log function takes 271 cycles for log(2) .

The ln(x) is calculated with the log function, as log(x) * ln(10). This is slower because the general multiply function is used after the log(x). The ln(2) takes 413 cycles. (So to reach my 10-second calculation goal, at least more than 40 instructions per second must be executed).

A faster, native ln(x) was also built but abandoned, to save program space.

The 10^x function is also in CALC_6, but is not yet accurate enough and only handles a small range at this time.

After the sin/cos/tan functions are also available, I will put the program in the logisim simulator to test everything on the gate level (eh.... coil and contact level).

And about the hardware.... it is expected to have approx. 270 DPDT relays.