Page:VN First Draft Report EDVAC Moore Sch 1945.pdf/11

 2.0 Main subdivisions of the system

2.1 In analyzing the functioning of the contemplated device, certain classificatory distinctions sug- gest themselves immediately.

2.2 First: Since the device is primarily a computer, it will have to perform the elementary oper- ations of arithmetics most frequently. These are addition, subtraction, multiplication and division: +, −, ×, ÷. It is therefore reasonable that it should contain specialized organs for just these operations.

It must be observed, however, that while this principle as such is probably sound, the specific way in which it is realized requires close scrutiny. Even the above list of operations: +, −, ×, ÷, is not beyond doubt. It may be extended to include such operation as √ , ∛, sgn, | |, also 10log, 2log, ln, sin and their inverses, etc. One might also consider restricting it, e.g. omitting ÷ and even ×. One might also consider more elastic arrangements. For some operations radically different procedures are conceivable, e.g. using successive approximation methods or function tables. These matters will be gone into in. At any rate a part of the device will probably have to exist, and this constitutes.

2.3 Second: The logical control of the device, that is the proper sequencing of its operations can be most efficiently carried out by a central control organ. If the device is to be, that is as nearly as possible , then a distinction must be made between the specific instructions given for and defining a particular problem, and the general control organs which see to it that these instructions —