Card handling in the AE

At least in the Sketch, the card handling is remarkably vague.

As opposed to electronic computers, the many kinds of cards is astonishing, in particular, as there are no explanation on how their movement is coordinated.

So far, these card types have been used:

• operation cards
• variable cards
• number cards

It seems fairly clear, that the operation cards just set the mill to one out of four arithmetic modes, and that the operation cards never start an action of the mill:

The Operation-cards merely determine the succession of operations in a general manner. They in fact throw all that portion of the mechanism included in the mill into a series of different states, which we may call the adding state, or the multiplying state, &c. respectively.

Throughout the text, it is often stressed that only a few operation cards are needed. This seems to be rather strange, as the operation cards are at most 25% of all cards, and they are small, as at most four holes are needed.

These control the transfer of numbers between the mill and the store, and come in to major flavors:

• Supplying-cards: transfer from the store to the mill
• Receiving-cards: transfer from the mill to the store

Each also comes – only hinted in the Sketch – for two destinations (normal and primed ingress) as well as sources, and the Supplying cards also may either leave the storage cell cleared, or have the value restored (see Destructive and retaining ingress operation).

As the mill has no unary operations, in every operation of the mill, two Supplying-cards and one Receiving-card is needed (unless the result is only needed to control a loop).

A hard to understand remark is:

It should be understood that the Variable-cards are not placed in immediate contiguity with the columns. Each card is connected by means of wires with the column it is intended to act upon.

Provided the storage can be cleared totally, the numbers initially required in the variables giving the function arguments, have to be provided by another card type.

Could not found the place in the Sketch.