The Digital World vs The Real World • Computers “speak” in terms of the binary language (“1” and “0”) which represent on and off pulses of electricity. • Digital is very discreet - either the pulse is there or it isn’t. • Our world is not discreet. We “speak” and hear along a continuous analog wave. • Our language is not discreet. What humans recognize as language must be converted to machine language.
The Digital World vs The Real World • A “machine cycle” is the amount of time that it takes for a computer to: • Fetch and instruction from RAM (which has been put there as an input process from our world) • Decode the instruction into machine language • Execute the instruction inside of the ALU • Return the result back to RAM (which is then returned to us as an output process by the OS) • Measured in terms of MHz or MIPS (millions of instructions per second)
Classification of computer systems • Microcomputers • Mainframes • Supercomputers
Microcomputers • Personal computer: single-user computer. Desktop model, laptop, notebook, subnotebook, Personal Digital Assistants (PDAs) • Workstations: special PCs designed to support applications that require more power than ordinary personal computing. • Embedded: microcomputer is embedded inside of another machine. • Convergent Technologies • Network computers
Supercomputers • Usually several large integrated computers. Used primarily in defense and scientific organizations to process enormous amounts of data extremely fast. • Finding more use in traditional transaction environments.
Mainframe • Large centralized computers. Normally used to process operational business transactions. Some firms may have more than one mainframe. • Usually supports hundreds or thousands of users. • Large data storage ability