The Digital World vs The Real The Digital World vs The Real WorldWorld

• Computers “speak” in terms of the binary Computers “speak” in terms of the binary language (“1” and “0”) which represent on and off language (“1” and “0”) which represent on and off pulses of electricity.pulses of electricity.

• Digital is very discreet - either the pulse is there or Digital is very discreet - either the pulse is there or it isn’t.it isn’t.

• Our world is not discreet. We “speak” and hear Our world is not discreet. We “speak” and hear along a continuous analog wave.along a continuous analog wave.

• Our language is not discreet. What humans Our language is not discreet. What humans recognize as language must be converted to recognize as language must be converted to machine language.machine language.

• A “machine cycle” is the amount of time that it A “machine cycle” is the amount of time that it takes for a computer to:takes for a computer to:– Fetch and instruction from RAM (which has been put Fetch and instruction from RAM (which has been put

there as an input process from our world)there as an input process from our world)– Decode the instruction into machine languageDecode the instruction into machine language– Execute the instruction inside of the ALUExecute the instruction inside of the ALU– Return the result back to RAM (which is then returned Return the result back to RAM (which is then returned

to us as an output process by the OS)to us as an output process by the OS)

• Measured in terms of MHz or MIPS (millions of Measured in terms of MHz or MIPS (millions of instructions per second)instructions per second)

The Digital World vs The Real The Digital World vs The Real WorldWorld

Classification of computer Classification of computer systemssystems

• MicrocomputersMicrocomputers

• MainframesMainframes

• SupercomputersSupercomputers

MicrocomputersMicrocomputers

• Personal computer: single-user computer. Personal computer: single-user computer. Desktop model, laptop, notebook, subnotebook, Desktop model, laptop, notebook, subnotebook, Personal Digital Assistants (PDAs)Personal Digital Assistants (PDAs)

• Workstations: special PCs designed to support Workstations: special PCs designed to support applications that require more power than ordinary applications that require more power than ordinary personal computing.personal computing.

• Embedded: microcomputer is embedded inside of Embedded: microcomputer is embedded inside of another machine.another machine.

• Convergent TechnologiesConvergent Technologies• Network computersNetwork computers

SupercomputersSupercomputers

• Usually several large integrated computers. Usually several large integrated computers. Used primarily in defense and scientific Used primarily in defense and scientific organizations to process enormous amounts organizations to process enormous amounts of data extremely fast.of data extremely fast.

• Finding more use in traditional transaction Finding more use in traditional transaction environments.environments.

MainframeMainframe

• Large centralized computers. Normally Large centralized computers. Normally used to process operational business used to process operational business transactions. Some firms may have more transactions. Some firms may have more than one mainframe.than one mainframe.

• Usually supports hundreds or thousands of Usually supports hundreds or thousands of users.users.

• Large data storage abilityLarge data storage ability