CS 0008 Day 2 1

Today Hardware and Software How computers store data How a program works Operators, types, input Print function Running the debugger 2

Hardware Physical devices; components CPU – central processing unit. Actually runs the program. Today: microprocessors which fit on a single chip Main memory – stores the program currently being executed and the data. E.g., your Python program and its variables; text editor and the document you are editing Random Access Memory – volatile – when the power is turned off, contents are erased 3

Hardware Secondary storage – holds data even when the power is turned off. Programs and documents you are saving are stored in secondary storage, and loaded into Main Memory as needed. Common: disk drive. Input devices – keyboard, mouse, scanner, microphone, sensors, etc. Output devices – video display, printers, etc. 4

Software Programs; code System software vs application software 5

System Software Controls and manages the computer Users typically do not modify it Operating system – fundamental! Controls everything. Arranges for data and programs to be loaded into Main Memory; arranges for programs to be run; manages I/O devices; etc. Linux, Mac OS, Windows are operating systems 6

Application Software Editors, powerpoint, spreadsheet programs, programs, web browers, programs, programs to calculate financial information, etc! 7

How Computers Store Data All information is converted into strings of 0s and 1s (really!) Bit – binary digit; 1/0; on/off Byte – 8 bits Storing numbers and letters (on the board) 8

How a program works On the board Then, back to Python 9