previous | contents | next

Chapter 6 The Whirlwind I computer 139

The scientific and engineering applications time on Whirlwind I has been organized in a manner patterned after that originated by Dr. Wilkes at EDSAC. The group of programmers and mathematicians assigned to WWI assist users in setting up their own problems. Small problems requiring only a few seconds or minutes of computer time are encouraged. Applications time is assigned in 1-hour pieces two or three times a day. No program debugging is allowed on the machine. Program errors are deduced by the programmer from printed lists of results, storage contents, or order sequences as previously requested from the machine operator. The programmer then corrects his program which is rerun for him within a day or perhaps within a few hours.

Every effort is made to reduce the time-consuming job of printing tabulated results. In many cases a user desires large amounts of tabulated data only because he doesn't really know what answers he wants and so asks for everything. Such users are encouraged to ask only for pertinent results in the form of numbers or curves plotted by the machine on a cathode-ray tube and automatically photographed. If these results prove inadequate or the user gets a better idea of his needs, he is allowed to rerun his program, again asking only for what appear to be significant results. Figure 1 shows a sample curve plotted by the computing machine showing calibrated axes and decimal intercepts.

Fig. 1. Sample computer output.

Fig. 2. Simplified computer block diagram.

WWI system layout

Figure 2 shows the major parts of any computer such as WWI. The major elements of the computer communicate with each other via a central bus system.

WWI is basically a simple, straightforward, standard machine of the all-parallel type. Unfortunately, the simple concept often becomes complicated in execution, and this is true here. WW's control has been complicated by the decision to keep it completely flexible, the arithmetic element by the need for high speed, the storage by the use of electrostatic storage tubes, the terminal equipment by the diversity of input and output media needed.

Control

The WW control is divided into several parts, as shown in Fig. 3.

Central control

The central control of the machine is the master source of control pulses. When necessary the central control allows one of the other controls to function. In general there is no overlapping of control operation; except for terminal equipment control, only one of the controls is in operation at any one time.

Storage control

Storage control generates the sequence of pulses and gates that operate the storage tubes. Central control instructs the storage control either to read or to write.

Arithmetic control

Arithmetic control carries out the details of the more complex arithmetic operations such as multiplication and division. The

previous | contents | next