Central Processing unit

Central Processing Unit

}    Complex set of electronic circuitry

}    Executes stored program instructions

}    Two parts

}    Control unit

}    Arithmetic/logic unit (ALU)

Control Unit

Arithmetic Logic Unit

Arithmetic Operations

Logical Operations

Types of Storage

The CPU and Memory

Temporary Storage Areas



How the CPU Executes Instructions

The Machine Cycle

Instruction Time

Execution Time

Finding Data in Memory

Memory Addresses

}    Each memory location has an address

}     A unique number, much like a mailbox

}    May contain only one instruction or piece of data

}     When data is written back to memory, previous contents of that address are destroyed

}    Referred to by number

}     Programming languages use a symbolic (named) address, such as Hours or Salary

Memory address

How Computers Represent Data

Representing Data




Storage Sizes

Main Types of Memory


}    Memory that can be instantly changed.

}    Requires current to retain values

}    Volatile

}    Holds data and instructions while they are in use.

}    Users typically refer to this type of memory

What’s in RAM?

Types of RAM

Types of RAM



The System Unit
The Black Box

}    Houses electronic components

}    Motherboard

}    Storage devices

}    Connections

}    Some Apple Macintosh models have system unit inside monitor

The System Unit
The Black Box

The System Unit
The Black Box


}    CPU etched on a chip

}    Chip size is ¼ x ¼ inch

}    Composed of silicon

}    Contains millions of transistors

}    Electronic switches that can allow current to pass through

Microprocessor Components

A Look Inside The Processor

Speed and Power

Components affecting Speed

Computer Processing Speed

System Clock

Microprocessor Speed

Bus Line

Bus Line

CPU can support a greater number and variety of instructions





Instruction Sets

Types of Processing

}    Serial processing

}    Execute one instruction at a time

}    Fetch, decode, execute, store

}    Parallel Processing

}    Multiple processors used at the same time

}    Can perform trillions of floating-point instructions per second (teraflops)

}    Ex:  network servers, supercomputers

Types of Processing

}    Pipelining

}     Instruction’s action need not be complete before the next begins

}    Fetch instruction 1, begin to decode and fetch instruction 2