first prototype assembled

 This the design for a prototype mechanism that has components to demonstrate several critical features:

• a 4-digit dual-cage digit stack that stores two 4-digit numbers
• movable and fixed long pinions that can do shifts  to multiply and divide by 10
• a 4-digit anticipating carriage that can do both addition and subtraction

The digit and carriage wheels have hidden fingers inside them used for "giving off", which is the process of reducing a value to 0 while transmitting it elsewhere. The fingers are engaged or disengaged by lifting or lowering a stacked set of sleeves around the digit wheel axis.

This arrangement will be sufficient to demonstrate simple algorithms, like computing numbers in the Fibonacci Series. It is not adequate for doing multiplication and division, however; that requires more digit stacks and perhaps a second anticipating carriage.

That is all "19th century" mechanism. But in the prototype tester, the rotation and lifting of the axes derive from a "21st century" mechanism below it with stepper motors, lead screws, and a Teensy microprocessor.

Here's the first version of the assembled prototype as it was on 2 Apr 2024. It has several bugs that need to be fixed.