Computer Hardware Organization(How does the computer look from inside?)

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Mainmemory

I/O bridge

Bus interface

ALU

Register file

CPU

System bus Memory bus

Disk controller

Graphicsadapter

USBcontroller

Mouse Keyboard Display

Disk

I/O bus Expansion slots forother devices suchas network adapters

Executable (machine language) program stored on disk

PC

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Computer Hardware – Buses

Electrical conduits connecting computer components

Transport bytes of information back and forth between components

Designed to transfer chunks of bytes called words

The number of bytes in a word (word size) is a fundamental system parameter

For example, Intel Pentium systems have a word size of 4 bytes (32 bits)

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Computer Hardware - I/O devices

The computer system’s connection to the external world

Examples, Keyboard(I), mouse(I), Screen(I), disk drive (I and O)

Each I/O device connects to the bus by a controller or an adaptor.

A Controller is a chip set in the device itself, or on the system’s main board (motherboard)

An Adaptor is a card that plugs into a slot on the motherboard

Purpose of controller or adaptor is to over see the transfer bits back an forth the I/O bus and the I/O device.

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Computer Hardware – Main Memory(MM)

MM is a temporary storage device (in what way temporary?) and connection to the external world

Holds both a program and its data which the program manipulates while the processor is executing the program

Physically, MM consists of a collection of Dynamic Random Access Memory (DRAM) chips.

Logically, MM is organized as a linear array of bytes, each with its own unique address.

The only operations MM understands is to read (transfer bytes from an address to CPU), or to write (transfer bytes from the CPU to a given address)

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Computer Hardware – Processor (CPU) The Central Processing Unit (CPU) interprets instructions

stored in MM

Among other things contains the following: Program Counter (PC), a register that contains the

address the next program instruction.

Registers, a collection of small storage devices – both special and general purpose.

Arithmetic/Logic unit (ALU), computes new data and address values (think of it as the calculator of the computer)

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Computer Hardware – Processor (CPU)

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Computer Hardware –CPU Process

FETCH - Read from MM the instruction (bits) whose address is in PC register.

DECODE - Interpret the bits in the instruction.

EXECUTE - Perform some simple operation dictated by the instruction.

In parallel, update the address in the PC register to the address of the next instruction.

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Computer Hardware – CPU Instructions

Load: Copy a word from MM into a register.

Store: Copy a word from a register to a location in MM.

I/O read/write: Copy a word between an I/O device and a register

Arithmetic: Add, subtract, multiply, divide.

Logic: And, or, not, xor, etc.

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CPU

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Main Memory

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Mother Board

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Printed Circuit Board

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Expansion Slots

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Disk Drive

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Case

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Power Supply

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