Part27
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Then and Now

The first computer I used was the NCR 102-A. It weighed about 2700 pounds, occupied 250 square feet, consumed 7.7 kilowatts, and required air conditioning and a separate power supply. The price for the basic system was about $82,000. There was no operating system and no program library. All programming was done in machine language.

Today a personal computer system consisting of computer, monitor and printer and weighing about 70 pounds fits comfortably on a desk and may be plugged into any grounded wall outlet. The cost of a basic system is about $1000 (A notebook computer can weigh as little as two or three pounds.) There are operating systems, higher-level languages, and a multitude of application packages, and also email and the World Wide Web.

Matrix inversion with punched card equipment was mentioned at the beginning of this paper with the inversion of a matrix of order 25 requiring 75 hours. Today a matrix of this size, once it has been assembled, may be inverted on a 233MHz computer using J which has a primitive operation for matrix inversion in about 0.015 seconds. The ratio in times is about 18 million, a figure which by itself probably has little meaning.

We give, for one last time, the sample problem written in the Simple Computer one-address code which although hypothetical is typical of machine-language programming of the 1950s. We also give a J Windows form for doing the calculations where even the very simple J program has been replaced by a few key strokes and mouse clicks.

     00 331  A <- 0
     01 434  N <- 0
     02 435  Sum <- 0
     03 436  Max <- 0
     04 600  Read Price
     05 433
     06 233  
     07 233   
     08 516  Is Price < 0?   
     09 334
     10 700  Print N
     11 335
     12 700  Print Sum
     13 336  
     14 700  Print Max
     15 800  Halt
     16 334  N <- N + 1
     17 132
     18 434
     19 335  Sum <- Sum + 1
     20 133
     21 435
     22 333  
     23 236
     24 504  Is Price - Max < 0?
     25 333  
     26 436  Max <- Price
     27 331
     28 232
     29 504  Trans. to 04  
     30   0
     31   0  Zero
     32   1  One
     33      Price
     34      N
     35      Sum
     36      Max
One-address
    Simple Computer
Sample Problem
For me these two forms of a program for the sample problem, the first in the spirit of the early programming languages and the second showing a modern graphical user interface which conceals even the simplest of programs, and displayed on the World Wide Web, indicate how computing technolgy and our understanding of its use have evolved in the almost fifty years of my association with the profession.


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