...... analog technique that folks buy these days in pre-made ICs .
And digital ones just for fun
A bunch of prototype analog modules are currently on the back-burner until parts arrive, so I've made a start on the digital section of this "analog-hybrid" computer. Here is what I've called the "Iteration Counter". It's a 4-bit programmable-n counter whose primary purpose will be, receiving its clock input signal form the computers master timing/controller unit, counting problem solving iterations and, patched into an electronic analogue multiplexer network, switching different sets of "initial conditions" and/or constants for each problem solving iteration.
Just for example, suppose you "write" a program to compute and plot the trajectory of a projectile or missile. The problem can be solved/plotted/displayed successively with anything from 2 to 16 different (multiplexed) constants (just for example) for gravity. The completed computer will have four of these counter modules, which can be either daisy-chained for patched independently to perform other functions.
All of the computers patchable digital logic will use open-collector inverted logic (0=1) with internal resistive pull-ups on all inputs. All I/O is designed to be blow-up proof, such that any I/O can be accidentally patched to a + or - 100V analog output without damage. The Iteration counter has a clock input, a reset input and 20 current-limited open-collector outputs with indicator LED's. There are sixteen decimal outputs (D0-D15) and four BCD outputs.
Here is a vid of it running; as shown, n-programming is achieved simply by patching the reset input to the appropriate decimal output. The 4 LED's on the far right are indicators for the BCD outputs.
Schematic is also attached, as well as a more readable form the Triangle Waveform generator schematic, with a couple of errors corrected.