1. Why build a computer? u Computers were developed to mechanize mathematical computations. u Two definitions:  A computer is “a programmable electronic device that can store, retrieve, and process data.” - Merriam-Webster Dictionary, 2000  A computer is “one who computes; a reckoner; a calculator.” - Webster’s Dictionary, 1828

2. Computer History u Mechanical devices (past - 1890) Mechanical devices u Electro-mechanical devices (1890 - 1942) Electro-mechanical devices u “Modern” Computers: 1st Generation - Vacuum tubes1st Generation - Vacuum tubes (1942 - 1959) 2nd Generation - Transistors2nd Generation - Transistors (1959 - 1965) 3rd Generation - Integrated Circuit3rd Generation - Integrated Circuit (1965 - 1971) 4th Generation - Microprocessor4th Generation - Microprocessor (1971 -)

3. u 1642 u Base-10 adding machine u Carried one digit to the next u Never really used Blaise Pascal (1623-1662) “Pascaline”

4. u 1694 u Base-10 multiplication machine u Worked by repeated addition Gottfried Leibniz (1646-1716) “Leibniz calculator”

5. u 1801 u Weaved patterns described by holes in punched cards u 1 st programmable device Joseph-Marie Jacquard (1752-1834) “Jacquard’s loom”

6. u 1822 u Calculated squares and cubes using the method of differences u Base-10 u Never completed Charles Babbage (1793-1871) “Difference Engine”

7. Charles Babbage (cont.) “Analytical Engine” u 1833 u Primary innovation:  The difference engine was single-purpose  The analytical engine was general-purpose u Anticipated modern computers by:  Separating processing from storage  Using punched cards for input u Was never built

8. u A supporter and mentor of Babbage u Translated material on the analytical engine u Suggested that punched cards could “instruct” the engine to perform and repeat operations u The Ada programming language is named for her Ada Augusta (1816-1852) “the first programmer”

9. u Mechanized the 1890 US census u Worked by electronically counting one card per person u Formed a company that eventually became IBM Herman Hollerith (1860-1929) “tabulating machine”

10. u 1942 u The first electronic computer u Snubbed by IBM u Never patented John Atanasoff (1903-1995) “Atanasoff-Berry Computer (ABC)”

11. Other Early Computers Colossus (1943 - Bletchley Park) Used by the British to break German codes in WWII ENIAC (1946 - U Pennsylvania) Used by the US Army to compute artillery firing tables Mark I (1944 - Harvard and IBM) Funded by the US Navy to compute navigation tables

12. Stored-Program Computers u ENIAC (1946 – U Pennsylvania)  18,000 vacuum tubes, hard-wired for task  Used to compute artillery firing tables u von Neumann’s draft report (1945)  “von Neumann” architecture u EDSAC (1949 - U Cambridge)  The first large-scale stored-program machine  Did not have to be rewired for a new task John von Neumann

13. UNIVAC u An updated version of the ENIAC. u Sold to the US census bureau and delivered in 1951 u Successfully predicted the outcome of 1952 presidential election based on early returns

14. IBM u UNIVAC’s success scared Thomas Watson, Jr. u IBM 700 series u “Big Blue” held 75% of the market by 1957 and dominated the industry for the next 25 years

15. PDP-8 u Using transistors made computers smaller, faster, and more reliable u Digital Equipment Corporation (DEC) built the PDP series starting in 1960 u The PDP-8, 1963, was the definitive mini-computer

16. IBM 360 u Using integrated circuits made computers even smaller, and capable of being mass produced. u The IBM-360 series, starting in 1964, was the definitive IC computer.

17. The Personal Computer u Altair (1975)  The Altair 8800 was the first affordable personal computer  256 bytes of memory u Apple II (1977) u IBM PC (1981) u Apple Macintosh (1984) u The PC Today (20__)