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MODULE V - FUNDAMENTALS OF ELECTRONICS Digital Basics of Computers Early computer programmers needed the digital basics to some way represent the human recognised numbers 10 to 15 under the decimal system in a way which still represented one decade. They conveniently chose A - F the first six letters of the alphabet and six in latin is "HEX". Hex-Decimal was born, six alphabetical characters with ten decimal numbers comprising a set of sixteen unique settings of bits all told. The first home computers such as my old personal favourite, the Apple II, had an eight bit "data bus" which dealt in "bytes" and had a sixteen bit (65,536 or 64K) "address bus". The only changes since the 1970's has been the ever increasing speed of the digital logic blocks contained within microprocessors, repeated doubling of the number of switches, (er sorry bits!) reduced power consumption for efficiency, and expanded on board "instruction sets" of micro-code for sharp programmers to use. Dead simple really. |
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By the way, computers and other digital devices can NOT multiply or divide, they can only add and subtract or shift a sequence of bits left or right. When a computer ostensibly multiplies 3 X 4 it actually deep down in the nitty gritty department of all those basic logic blocks shown in figure 3 above, which are buried deep within your IBM or Mac microprocessor, takes the number four, adds four again and; finally adds four again to get twelve. Anyone who tells you otherwise reveals a deep ignorance of digital basics, trust me. Want more proof? Take the word "proof". In ASCII format the word "proof" in lower case is five letters of the alphabet represented as a sequence of hex-decimal bytes as follows -
in decimal format that would be 112 114 111 111 102 A computer looks at those sequence of bytes to "interpret" the word "proof". To achieve that colour change to red I used the html instruction <font color="#FF0000"> which of course is a six byte instruction in hex-decimal. As an exercise for yourself see if you can see how the conversion from hex-decimal to decimal equivalent for the word "proof" occurs. O.K. it's just digital basics. Digital Works 3.04 is a graphical design tool that enables you to construct digital logic circuits and to analyse their behaviour through real time simulation. Its intuitive, easy to use interface makes it the ideal choice for learning or teaching digital electronics. You can even prototype simple digital electronic circuits before you actually build them. You can download a free, fully functional evaluation copy of Digital Works for Windows 95, 98 and NT 4 Download Digital Works 3.04 - 1659 Kb |
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