24.1 Understanding high performance computing  (Page 2/6)

Well, wrong. The task of driving from Houston to Dallas cannot be divided into tasks that can be done in parallel. The task can only be done by one person driving in a line from Houston to Dallas in 5 hours. I used the word "line" because it helps connect us to the word: linear . A linear task cannot be broken-up into smaller tasks to be done in parallel by multiple workers. Within the computer world, the word associated with linear concept is sequential processing . I must drive one mile at a time in sequence to get to Dallas.

Our natural tendency is to share the work that is to work in parallel whenever it is possible. As a group we can accomplish many tasks that can be done in parallel in less time.

The birth of computers – a "parallel" to central processing unit (cpu) story

ENIAC, short for Electronic Numerical Integrator And Computer, was the first general-purpose electronic computer (July 1946). It was the first Turing-complete, digital computer capable of being reprogrammed to solve a full range of computing problems. ENIAC had twenty ten-digit signed accumulators which used ten's complement representation and could perform 5,000 simple addition or subtraction operations between any of them and a source (e.g., another accumulator, or a constant transmitter) every second. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher due to parallel operation.

Often not understood by many today, the first computer used base 10 arithmetic in the electronics and was a parallel processing machine by using several accumulators to improve the speed. However, this did not last for long. During its construction:

The First Draft of a Report (commonly shortened to First Draft) on the EDVAC – Electronic Discrete Variable Automatic Computer was an incomplete 101 page document written by John von Neumann and distributed on June 30, 1945 by Herman Goldstine, security officer on the classified ENIAC project. It contains the first published description of the logical design of a computer using the stored-program concept, which has come to be known as the von Neumann architecture.

The von Neumann architecture is a design model for a stored-program digital computer that uses a [central] processing [unit]and a single separate storage structure to hold both instructions and data. It is named after the mathematician and early computer scientist John von Neumann. Such computers implement a universal Turing machine and have a sequential architecture.

Von Neumann also proposed using a binary (base 2) numbering system for the electronics. One of the characteristics of the von Neumann architecture was the trade off of multiple processors using base 10 electronics to a single central processor using base 2 (or digital) electronics. To compare to our ant example, the idea was to use one real fast ant versus 10 slow ants. If one real fast ant can do 1,000 tasks in an hour; it would be more powerful (be able to do more tasks) than 10 ants doing 10 tasks an hour or the equivalent of 100 tasks per hour.