Software Development at the Eckert-Mauchly Computer Company Between 1947 and 1955
Yüklə 1,23 Mb. Pdf görüntüsü
|
- Bu səhifədəki naviqasiya:
- EMCC Reaching Out
- Programming the UNIVAC
Iterations – Norberg – Software Development at EMCC 9
for use on UNIVAC I. This suggests that the approach to programming inside IBM was similar to that inside EMCC, where IBM programmers saw needs similar to those perceived by EMCC programmers. Second, IBM programmers traded on their advanced knowledge of business and engineering problem solution developed for tabulator operations over the previous two decades, an experience that no one in EMCC possessed outside of the Aberdeen problems area. Here EMCC stood at a disadvantage, and therefore took longer to develop a strong approach to programming. Thus, UNIVAC I’s delivered possessed few applications programs, though they did arrive with basic programming structures available for programming applications by the customers, along with instructions on how to program the applications.
The applications group, especially Mauchly, identified a need to provide training for incoming programmers, engineers, customers, and sales personnel, an area already deeply embedded in the business approach of IBM. As a result, several members of the group worked on a training manual and developed a course to be offered either at EMCC or at the customer’s site. 22 The course began with defining the operating code for UNIVAC and an introduction to programming in which several short examples of coded operations were presented. Subsequent lectures included description of flow-charting, types of subroutines, collation, and matrix algebra. Students spent substantial time on specific examples to understand operations like floating point, round off, problems of tape wear, etc. 23
While all this coding activity was going on, Mauchly, as President of EMCC, was extremely busy visiting many customer and potential customer sites. For example, between October 28 and November 14, 1947, Mauchly hosted visitors and took two trips to New York City and one to Chicago. There were multiple visits with representatives from A. C. Nielsen, Northrup, and Prudential Insurance. He participated in drafting proposals for sales, interviewing candidates for positions at EMCC, conferences with staff on design questions, and oversaw the applications group. 24
Mauchly were in on Sundays. Eckert’s idiosyncratic work habits sometimes led him to stay at work around the clock. 25
Returning to the discussion of applications efforts at EMCC, as the use of ENIAC and the other computer systems of the middle 1940s showed, there was a large class of engineering and scientific problems that could be attacked using electronic computers. Mauchly, with his interest in weather problems, which had led him to be interested in electronic computation methods in the first place, was in a good position to know this. Thus, it is Iterations – Norberg – Software Development at EMCC 10
no surprise that among the applications group there were people thinking about the solution to such problems. The better posed problems involved partial differential equations that could be solvable using finite difference techniques. Betty Snyder and Hubert M. Livingston investigated various solutions for the plane potential problem. This pair published an article in 1949 in which they presented a computer program for the UNIVAC to solve the Laplace boundary value problem. 26 They set up a two- dimensional space, and used a finite difference method originally proposed by H. Liebmann in 1918. 27 The article opened with a very brief description of the UNIVAC system, including a list of the instructions to be used in the solution of this problem. As is typical in the solution of such problems, the authors set up a region, in the example a rectangular space, though they argued how irregular spaces could be examined as well, with a mesh of horizontal and vertical lines, and set up the equations to calculate approximations for the partial differential equation that led to a set of difference equations. The number of equations resulting is equal to the number of interior mesh points. Either a direct or iterative method can be used to solve the linear system of equations. The authors discussed the availability of subroutines for use in these problems, and in a company document on the subject intended for circulation, discussed truncation errors, scale factors, and times of solution. 28 This problem is representative of the types of research going on in this group in the late 1940s.
Programming the UNIVAC
From 1947 on, coders at EMCC developed a number of subroutines for both mathematical and business use. By 1951, the number of subroutines had increased to the point where they needed to put some order into them to increase efficiency of use. While the other members of the Applications Department continued their work on programs and routines, including diagnostic routines, for UNIVAC I, Hopper assumed an interest in automatic programming. She attempted to meld the operations of the computer system and its programs with the use of subroutines. This idea of subroutines was exploited at EMCC before she arrived, as we saw above in the work of Betty Snyder. Hopper’s contribution was to make it possible not just to call up a routine from memory, but, if necessary, actually construct a subroutine program, insert it into a program, and carry out the computation. The process of translating a subroutine into a program received the name “compiler.” The needed information was delivered by UNIVAC under the control of an operation they called a “differentiator.” The differentiator delivered the information necessary to program the computation of a function and its derivatives. The actual derivation of the function was done by the computer system, not by the programmer as before. Thus, the UNIVAC became capable of developing a completed program. 29
Yüklə 1,23 Mb. Dostları ilə paylaş:
|