HOW INFORMATION COMES
OUT OF THE MACHINE
At either one of the two recorders ([Fig. 1]), information comes out of the machine, either in the form of printed characters or as punched tape. The recorder consists of a printer, a reperforator, and a tape transmitter. One recorder table belongs to each computer and records the results it computes. The printer is a regular teletypewriter connected to the machine. It translates information produced by the machine as electrical impulses and prints the information in letters and digits on paper. The reperforator is an automatic tape punch. It translates information produced by the machine in the form of electrical impulses and punches the information on paper tape. Next to the tape punch is a tape transmitter. After the tape comes through the punch, it is fed into the transmitter. Here the machine can hunt for a previous result punched in the tape, read that result, and use it again.
HOW INFORMATION IS MANIPULATED
IN THE MACHINE
The main part of the computing system consists of 27 large frames loaded with relays and wiring, called the computer, or Computer 1 and Computer 2. In this “telephone central station,” all the “phone calls” from one number to another are attended to. There are 8 types of these frames in the computer:
| Frames | Number |
|---|---|
| Storing register frames | 6 |
| Printer frames | 2 |
| Problem frames | 2 |
| Position frames | 2 |
| Calculator frames | 6 |
| Control frames | 2 |
| Routine frames | 4 |
| BTL (Block-Trig-Log) frames | 2 |
| Permanent table frames | 1 |
| Total | 27 |
In most but not quite all respects, the two halves, Computer 1 and Computer 2, can compute independently. The storing register frames hold enough relays to store 30 numbers. The registers for these numbers are named A, B, C, D, ···, M, N, O in two groups of 15 each. One group belongs to Computer 1 and the other to Computer 2. In each Computer, the calculator frames hold enough relays for storing two numbers (held in the X and Y registers) and for performing addition, subtraction, multiplication, division, and square root. In each Computer, the problem frame stores the numbers that are read off the problem tape and the table tapes, and the printer frame stores the numbers that are read into the printer. The printer frame also stores indications, for example, the signs of numbers, plus or minus, for purposes of combining them. These frames also hold the relays that control the printer, the problem tape, and the table tapes. Jointly for both Computers, the position frames connect a problem in some problem position to a Computer that becomes idle. For example, one problem may finish in the middle of the night; the machine automatically and unattended switches to another problem position and proceeds with the instructions there contained. A backlog of computing on hand can be stored in two of the problem positions, while the other two control the two Computers. In each Computer, the routine frames hold the relays that make the Computer follow the routine instructions. Jointly for both Computers, the remaining frames—the control frames, the BTL frames, and the permanent table frames—hold the relays that control: the alarms and lights for indicating failures; some circuits called the BTL controls; the tape processor; and the mathematical tables that are permanently wired into the machine. The permanent table frames hold the following mathematical functions ([see Supplement 2]): sine, cosine, antitangent, logarithm, and antilogarithm.
Storing
Numbers can be stored in the machine in the 30 regular storing registers of both Computers together. They can also be stored, at the cost of tying up some machine capacity, in the other registers: the 4 calculator registers, the 2 problem registers, the 2 table registers, and the 2 printer registers. Numbers can also be punched out on tape, in either of the two printers, and later read again from the tape. Labels identifying the numbers can also be punched and read again from the tape.
Each register in the machine stores a number in the biquinary notation, as explained above. In programming the machine, after mentioning a register it is necessary—as a part of the scheme for checking—to tell the machine specifically whether to hold the number in the register or to clear it.