Grace Hopper: Computer Scientist

Grace Hopper: Computer Scientist — page 5 — Octal vs Decimal Octal is a number system consisting of eight single-digit numbers zero one two three four five six and seven It is a base-eight system in contrast to the base-ten system that people use commonly When she worked with BINAC Hopper had to convert decimal numbers into octal equivalents BINAC would then convert the octal numbers into binary code which consists of two numbers zero and one The zeros and ones worked like on and off switches with one being on and zero being off Binary code could run faster than coding of normal numbers Even today’s computers store information and operate in binary Yet in 1949 data was still being entered largely by people tapping numbers on keypads Entering information in binary takes a lot of time and numbers Octal helped reduce the size of those numbers For example the number ten in binary must be entered as 1010 In octal it must be entered as 12 That change saved time and reduced the potential for mistakes to use as well as for scientific purposes He Mauchly was envisioning much larger problems which hadn’t even been stated yet Hopper recalled He was visualizing the use of computers in the business and industrial area the things that they would be able to do 1 Hopper had become head of the software division at EMCC and she was assigned to program UNIVAC A programmer provided the computer with a list of instructions to carry out This was done using a punch card which was a stiff piece of paper with holes punched in specific patterns that represented data These were inserted into the computer which read the holes in the cards and translated them into information Hopper hired a team of four men and four women to assist her in building a collection of 8

Grace Hopper: Computer Scientist — page 6 — SCIENCE SPOTLIGHT PUNCH CARDS Modern computers allow users to save files which can be opened and changed at any time However when Hopper was beginning to work with computers data was accessed by inserting a punch card into the computer Punch cards were created by inserting a thick paper card into a punch card machine Holes were then punched in columns to represent characters Once the punch card was completed the desired data was stored on the card One drawback of the punch card was that it held a limited number of holes and therefore limited data If a large amount of data needed to be stored multiple cards were necessary It was crucial that the cards remained in a stack in the correct order so that the machine could read the data in the correct order When the user loaded the program each card was inserted into a punch card reader that input the data from the cards into the computer Punch cards date back to the early 1700s Textile looms could be controlled by punch cards The loom followed a sequence of operations based on white punch cards with holes and wove patterns based on the data the cards provided In 1725 a French weaver named Joseph-Marie Jacquard used punch cards to create a self-portrait woven in silk 9

Grace Hopper: Computer Scientist — page 7 — useful punch cards containing information for UNIVAC Some of the team members were people she had worked with before EMCC was building the first UNIVAC computer which was to be used by the US Census Bureau Hopper and her team made the UNIVAC project a success The computer was able to work with both numerical and alphabetical data inputs It was also the first computer to separate input and output The new computer featured a code that was closer to Hopper’s vision of how humans and computers could communicate John Mauchly wrote the C-10 code assembly language for the UNIVAC I and it has been the basis of most codes since Hopper recalled years later A was add M was multiply B was bring C was clear it was a beautiful code 2 The first UNIVAC computer was delivered to the US Census Bureau in 1951 TEACHING COMPUTERS TO UNDERSTAND HUMANS Hopper continued to think about how to make it faster and easier for humans to work with computers In May 1952 Hopper presented a paper at a meeting of the Association for Computing Machinery in Pittsburgh Pennsylvania The paper outlined a new and radical idea Why not teach machines how to assemble their programs instead of having humans input every step of each program Hopper’s paper suggested 10

Grace Hopper: Computer Scientist — page 8 — that computers could be given sets of instructions on how to perform simple common tasks She called these simple tasks subroutines In many ways programmers were already working in this way Programmers often used the same short sets of instructions to create more complex programs Yet each time they created a new program they had to input the subroutines yet again which took a lot of time and often resulted in mistakes Hopper proposed that these subroutines could be thought about like books in a library Each subroutine told the computer how to do something By organizing the subroutines into a catalog users could tell the computer which subroutines it needed to look up and in what order to do its job Hopper finished her description of this new program generator by The US Census Bureau Computer-Innovation Pioneer EMCC’s first UNIVAC computer was funded by the US Census Bureau Beginning in 1790 the bureau was charged with tracking population demographics to determine how congressional seats should be allocated Yet by 1880 there were more people in the United States than could be effectively counted by the bureau’s manual data-processing abilities As it was 1,500 clerks worked more than seven years to produce the bureau’s report The bureau turned to engineer Herman Hollerith for assistance in tabulating results of the 1890 census Hollerith developed a system to record a person’s identifying information as a series of holes punched in cards which could then be read by machines Hollerith went on to become one of the founders of the company later known as International Business Machines IBM The Census Bureau used UNIVAC to tabulate part of the 1950 population census along with the entire 1954 economic census 11

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