What's in the Box?

How Computers Work - what’s inside:

Today [2018] computers are boxes that do procedures, not very different from the people called computers in the past.

Procedures can be implemented at different levels. We can use a simple calculator, where we obtain a number but use the number somewhere else. Or we can envision an entire factory as a computer, calculating, measuring and fabricating until a product is finished.


Let’s start with a simple calculator. By last century, mechanical calculators were desktop machines, not much different from Pascal’s calculator from the 1600s. The SCM calculator I used to keep books for my father’s machine shop performed addition, subtraction, multiplication and division on integer numbers. Sometimes it jumped up and down as it moved its carriage back and forth to perform carries from one column to the next.


The first pocket digital calculators came from HP, TI and Sinclair in the 1970s. They had only a few registers to hold numbers, usually the main accumulator, which was displayed at the top and sometimes one or more extra memory registers inside. All operations were performed by pressing buttons on the front panel, usually below the display.




The first computers were very similar - only a few registers and operations. The difference was the operations came from memory instead of from the panel buttons. And the memory was now large enough to hold several numbers plus several instructions as well. Most computers today are of this type, named after John Von Neumann, although he said Turiing came up with the idea both data and programs being in the memory. Here is an early computer program on a plug board:





By the time we got to the 1960s, a small minicomputer often had 4096 words of memory, 12 bits wide. Soon they had 16 or 32 bit words and 64K or more of memory and could do a hundred different operations.  Here is the control panel of a DEC PDP11:


[see more: Excellent explanation of internal  computer / calculator registers on Quora.com ]


Supercomputers:

In the 1960s, I worked on the first supercomputer, the Control Data 6600. It was the first machine which could do 1 MIPS, one million instructions per second. Using the largest numbers with a floating decimal point, this was called a MegaFlop.

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NOW: Operating Systems - What is hidden inside your computer. 

BTW, this is what I do.

As technology changed, the resources in computers increased greatly and larger programs could be executed. People gathered and shared collections of useful programs - some to read  data, some to print output, and some were shared math routines. A complete computer “run” consisted in loading all the parts needed together into the computer. This was so clumsy that people began to retain their setup in the computer from one run to the next. The part that was retained inside the computer came to be called the “Operating System.” Operating systems became the DOS, UNIX and Windows of today.


Operating systems also became more like we think. 

Now we are getting to the good stuff !!!


   … more coming … 2018-03-16 12:02:10

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© Gareth Harris 2018        -         Contact email: GarethHarris@mac.com         -         see also: SentimentalStargazer.com