Take a number out of Register _A_; put the number into Register _B_; and perform operation _C_. The first group of 8 holes at the left is called the _A field_ or the _out-field_. Here we tell the machine where a number is to be taken from. The middle group of 8 holes is called the _B field_ or the _in-field_. Here we tell the machine where a number is to be put. The last group of 8 holes is called the _C field_ or the _miscellaneous field_. Here we tell the machine part or all of the operation that is to be performed. To illustrate (see Fig. 10), we have holes 3, 2, 1 punched in the _A_ field, holes 3, 2 punched in the _B_ field, and hole 7 punched in the _C_ field. Now 321 is the _code_—or machine language, or machine call number—for storage counter 7; 32 is the code for storage counter 6; and 7 in the _C_ field is the code (in this case, and generally) for “Add, and read the next line of coding.” So, if we punch out this line of coding and put the tape on the machine, we tell the machine to read the number in counter 7, add it into counter 6, and proceed to the next line of coding and read that. The holes in each group of 8 holes from left to right are numbered: 8, 7, 6, 5, 4, 3, 2, 1. The code 631, for example, means that holes 6, 3, 1 are punched and that no holes are punched at 8, 7, 5, 4, 2. Since it is more natural, the code is read from left to right, or 631, instead of from right to left in the sequence 136. The devices in the machine have _in-codes_, used in the in-field, and _out-codes_, used in the out-field. For each of the 72 regular storage counters, the in-code and the out-code are the same. The first 8 storage counters have the codes 1, 2, 21, 3, 31, 32, 321, 4, 41; the last 2 storage counters, the 71st and the 72nd, have the codes 7321, 74. The constant registers—often called _constant switches_, or just _switches_—naturally have only out-codes, since numbers can be entered into the constant registers only by setting dial switches by hand. The first 8 constant registers have the out-codes 741, 742, 7421, 743, 7431, 7432, 74321, 75, and the 59th and 60th constant registers have the out-codes 821, 83. Transferring, Adding, and Clearing Each storage counter has the property that any number transferred into it is added into it. For example, the instruction Take the number in switch 741; transfer it into storage register 321 is coded: 741, 321, 7 The 7 in the third column is an instruction to the sequence-tape feed to turn up to the next coding line and read it. If any number is already stored in register 321, the content of 741 will be added to it, and the total will then be stored in 321. Resetting or clearing a regular storage register is accomplished by a coding that is a departure from the usual scheme of “out” and “in.” The instruction Clear register 321; read the next coding line is coded: 321, 321, 7