DIY prototype RPN/TENKEY programmable calc with printer <:3)--

[macieksoft]

The keys on the right are for tenkey operations. Without shift they affect tenkey adder no1, with shift they affect adder no2. * key is quite funky. First press basically pops the adder's value on the RPN stack, second press clears the adder (just like it used to do on those office calcs).
Above tenkey keys there is a key for adding into statistical registers and one for entering into alpha mode (for programming the ASCII text).

On the left there is a RPN section, those keys affect RPN stack. + and - keys can also affect memory when used with shift (memory add and memory subtract).

There is also multifunction encoder. It can be used to select display mode, ammount of decimal places to display, scroll the program listing, select memory cell holding time of reference for stopwatch mode or scroll the ASCII list in alpha programming mode.