Computer History

Random and brief.

20 flashcards · History · by lakesare

1. Why binary computers won?

   It is possible to use transistors in eg 10-nary, by determining what current means would be hard AND inefficient (eg would require thrice as much circuitry for twice as much information stored). So we just made signals to be as far as possible from each other. Links: stackoverflow answer

2. Abacus can probably be considered the first computer.

3. Why did Charles Babbage invent a difference engine?

   People used pre-computeted tables, eg searched in a book a square root of 4324323432. In war they also used tables. But if cannon was changed, the whole new table would have to get created, it takes long.

4. What's a Difference Engine?

   Mechanical special-purpose calculator designed to tabulate logarithms and trigonometric functions by evaluating finite differences to create approximating polynomials. The machine could accept a number, compute the value of the number squared, and then punch the result into a copper engraver’s plate with a steel die.

5. What's an Analytical Engine?

   First design for a general-purpose computer that could be described in modern terms as Turing-complete!

6. Despite this groundwork, Babbage's work fell into historical obscurity.

   Analytical Engine was unknown to builders of electronic computing machines in the 1930s. They needed to re-invent many of the architectural innovations Babbage had proposed.

7. Pascal invented these calculating machines. The adding operation was done by a person, who turned the wheels, and the machine, which did the carrying-over operation.

   Kind of like abacus, but does the carry-over.

8. Why is byte = 8 bits?

   Historic. The byte was originally the smallest number of bits that could hold a single character. Using 8 bits, you can describe 256 things, which is enough to encode in ASCII.

9. What's a stored-program concept?

   An idea of storing program in RAM of a computer. This idea, known as the stored-program concept, is usually attributed to the ENIAC designers, most notably the mathematician John von Neumann, who was a consultant on the ENIAC project. Alan Turing developed the idea at about the same time.

10. The processing unit in Babbage’s analytical engine was made of cogs, wheels and gears. What was the next great idea?

    The next great idea in the development of computers was to use vacuum tubes, as done in 1943 for 'Eniac' computer.

11. Why is the switch from cogs and gears => vacuum tubes such a progress?

    Vacuum tubes have no moving parts! It's the beginning of solid-state electronics. It allowed them to be fast and to not wear out.

12. When were transistors invented?

    In 1947, at Bell Labs. Transistor functions just like a mechanical relay or a vacuum tube. But is smaller and faster.

13. What's this?

    That's the insides of a TV before PCBs (Printed Circuit Boards) were invented:

14. Explain Moore's law.

    Moore observed that the number of transistors that could be out on a single chip was doubling every year and correctly predicted that this trend will continue into the near future.

15. What switches tech did Eniac use?

    Vacuum tubes. Eniac was built between 1943 and 1946, and transistors were invented in 1947. At any time, only one vacuum tube was in the ON state, representing one of the 10 digits.

16. What was the major drawback in Eniac (well, apart from vacuum tubes)? What was the solution?

    It had to be programmed manually by setting switches and plugging and unplugging cables. Thus, it was extremely tedious to enter and alter programs for the ENIAC. It would be much easier, and more desirable, if programs could be separate from the computer and simply read-in by the computer, as with Babbage’s analytical engine. John Von Neumann was a mathematician, and a consultant on the ENIAC project. He saw this drawback, and proposed 'Von Neumann machine' architecture instead, which would st…

17. What's Von Neumann architecture?

    Computer architecture based on a 1945 description by the mathematician John von Neumann with these components: A processing unit that contains an arithmetic logic unit and processor registers A control unit that contains an instruction register and program counter Memory that stores data and instructions External mass storage Input and output mechanisms

18. What are integrated circuits (ICs)?

    The integration of large numbers of tiny transistors into a small semiconductor chip results in circuits that are smaller, cheaper, and faster than those constructed of discrete electronic components. Cost is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high because the IC's components switch quickly and co…

19. What does Intel stand for, who founded it?

    Intel = INTegrated ELectronics. Gordon Moore (author of Moore's law) founded it along with Robert Noyce.

20. What's a microprocessor?

    Processor (CPU) shipped as a single IC was called a microprocessor, because it was so beautifully small.