Hi,
How are you going to display 0 (zero) and D, unless you use lower case d.
Display 1 (one) and i, you will have to use a single vertical segment for i.
I gather you want to display any combination A01 to A10, B01 to B10, etc up to J01 to J10.
The 11th button does a clear, 000.
Do I have the concept right.
All the buttons means you keep the maximum number of presses for any number will be 10, to get A10 or B10 etc.
You could use two rotary encoded switches, one switch as you turn it , selects A to J.
The other switch selects 1 to 10.
This way is you get the letter or number wrong you just turn the rotary switch back or forward to the right one.
It simplfies the controls to two knobs and a reset button.
Tom... 