Introduction to ComputersChapter 2Computers are common in every facet of

human activity.They overcome the shortcomings of

conventional radiography systems computers offer several advantages

1. They process information 2. Store that processed information 3. Retrieve what has been stored 4. Communicate information quickly and

accurately

Define computer…A machine for solving problems.What is a computer system?Hardware, software, and computer users.What is hardware?The physical components of the machine.What is software?The instructions that make the hardware

work to solve problems.Why are computer users important?They design, develop, and operate the

hardware and software.

History

Computers date back over 2000 yearsToday CT scanners are in their 5th

generationThey are classified according to their

processing capabilities, storage capacity, size, and cost.

There are four main groups...

Supercomputers

Processes data at extremely high speedsUsed in oil exploration weather forecastsresearch (especially in weapons)

Mainframes

Capable of rigorous computations at high speeds

Large primary memories and can support many pieces of peripheral equipment

Used in banksUniversities and CollegesLarge businesses and the government

Minicomputers

A midlevel computerperforms complex computations while

dealing with a high level of input and output from the users

frequently connected to other minicomputers on a network

CT Scanners and MRI Scanners

Microcomputers

Personal computers - PC’sSmall digital computers such as laptops and

notebooks.

Binary System

Decimal system has a base of 10 values are represented as 0 through 9 any decimal number can be written as a sum of

these digits multiplied by a power of 10.

The binary system has a base of 2 values are represented as 0 and 1

Terminology

A binary digit, or a bit, is a single binary number

4 bits = nibble8 bits = byte16 bits = word32 bits = double wordMemory capacity is measured in bytes...

1 thousand bytes = 1 kilobyte KB1 million bytes = 1 megabyte MB1 billion bytes = 1 gigabyte GB1 trillion bytes = 1 terabyte TB

Analog to Digital Conversion

The ADC converts the analog signal into a sequence of numbers having finite precision

Converts the analog signal into digital data for processing

Digital to Analog Conversion

Outputs digital data that are converted into the analog signals needed to operate analog display devices such as television monitors.