5.1 Computer basics: number systems, codes, logic, algorithms and spreadsheets notes

1. 5.1.1Algorithms and flowcharts: symbols, properties and examples

   An algorithm is a finite, step-by-step, unambiguous method for solving a problem; a flowchart draws the same steps with standard symbols joined by arrows.

   Advanced · 8 min · Read here
2. 5.1.2Number systems: binary, octal, hexadecimal and conversion to and from decimal

   A number system is fixed by its base (radix): computers work in binary (base 2), and octal (base 8) and hexadecimal (base 16) are short ways of writing binary; any base converts to decimal by adding digit × place value, and decimal converts to any base by repeated division (whole part) and repeated multiplication (fraction).

   Advanced · 6 min · Read here
3. 5.1.3Spreadsheets: cells, ranges, formulas, cell references, functions, editing and printing

   A spreadsheet is a grid of rows and columns whose cells hold numbers, text or formulas; formulas recalculate automatically when any value they use changes.

   Advanced · 9 min · Read here
4. 5.1.4Codes (BCD, ASCII, EBCDIC, Unicode), bits, bytes, words and computer memory

   Computers store everything as bits; codes (BCD, ASCII, EBCDIC, Unicode) decide which bit pattern stands for which digit or character, and memory holds these patterns in a hierarchy from fast, small registers and cache to large, slow secondary storage.

   Advanced · 7 min · Read here
5. 5.1.5Binary arithmetic and complements; logic gates and logical operations

   The ALU does arithmetic on binary numbers (adding, and subtracting by adding the 2's complement) and logical operations (AND, OR, NOT, XOR) bit by bit; these are built from logic gates, and NAND or NOR alone can build every other gate.

   Advanced · 8 min · Read here

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