Historical perspectives of computerized imaging

Computer classifications

Components of computer hardware

Define computer terminology

Are often classified according to size, processing speed, and storage capacity.

Supercomputers – are the fastest and highest-capacity computers, containing hundreds to thousands of microprocessors (eg: weather forecasting)

Mainframe computer – are fast, mid-to-large –size, large-capacity system that has multiple microprocessors. They can support a few hundred to thousands of users (eg: ATM’s)

Workstation – powerful desktop system usually connecting individual users to a larger computer system to share and transfer information

Microcomputers – best known as PC’s or palm pilot.

1946 - First all electronic, general purpose digital computer

Basic form = input, output, and processing devices

Input devices: keyboards, mice, microphones, barcode readers, touch screens, and image scanners.

Output devices: monitors, printers, and speakers

Processing: central processing unit (CPU)

Computers operate on the Binary Number System

It has only two digits, 0 and 1

Computers function by converting all data into binary values.

Represents one character, digit, or value.

A bit describes the smallest unit of measure 0 or 1 – computers ultimately understand only 0 or 1

Byte are 8 bits

Alphabet in Binary

Analog refers to a continuously varying quantity

A digital system uses only two values that vary discretely through coding. Binary Number System

Analog - one value blends into another

(like a thermometer)

Digital - distinct separation

98.6 exact

0

20

40

60

80

100

1st

Qtr

3rd

Qtr

East

West

North

Computer processing is performed by a series of transistors.

Transistors are either on or off. ◦ If the transistor circuit is closed and current

passes through, it is assigned a value of 1. ◦ If no current passes because of the circuit being

open, then 0.

Transistors can be switched on and off Transistors can be switched on and off millions of times in a second. Each 1 or 0 is millions of times in a second. Each 1 or 0 is a bit. a bit.

One byte is the amount of memory needed to store one letter.

A kilobyte represents 1024 bytes, megabyte is 1 million bytes, gigabyte is approximately 1 billion bytes

Memory is talked about in kilo, mega, giga, or tera.

Hardware – the nuts & bolts of the computer

Software – computer programs

Hardware: Motherboard – the largest circuitry board inside the computer and it contains many important small components.

Central processing unit, or microprocessor is the brain of the computer.

It is a small chip found on the motherboard. (not the “box” as most people refer)

CPU = a series of transistors that manipulate data received from the software.

Basic tasks are to read data from storage, manipulate the data, and then move the data back to storage or send it to external devices, such as monitors or printers.

CPU’s are named after its manufacturer and the speed at which it manipulates data.

The basic input/output system.

A simple set of instructions to bring the computer to life and run diagnostic test to make sure the peripherals are functioning.

ROM = Read-only memory. Contains information supplied by the manufacturer, cannot be written on or erased. (how to start the system)

After start up, BIOS oversees the basic functions of receiving and interpreting signals from the keyboard and other ports.

BIOS is the intermediary between the operating system (OS) and the hardware.

The bus provides the connections for the information to flow within the computer.

There are several: ex. connecting the microprocessor and the system memory (graphics port, video adapters, universal serial bus)

RAM = Random access memory. ◦ Data can be stored or accessed at random from

anywhere in the main memory. ◦ Only temporary storage when the computer is

turned off RAM is wiped clean. ◦ Usually expressed as MB (mega), GB (giga) or TB

(tera)

CMOS = (complementary metal oxide semiconductor) retains information about the hardware while the computer is turned off. Ex: date and time

Connectors sticking out of the back of the PC

Parallel (printer port) = 8 bits of data through the connection.

Serial (mouse) = 1 bit of data down a single wire.

USB (universal serial bus) = multiple devices may be connected into one port.

Sound Card

Network Card

Provides electricity and contains a fan to keep the computer cool.

Contains a transformer that converts AC from the wall to DC.

The main storage for programs and documents.

DVD’s can hold up to 7 times more than the CD.

3 types of CD/DVD:◦ ROM (read-only memory)◦ R (write once-read many)◦ RW (read and write many times)

Starting in the center and spiraling out.

Tiny depression (pit) is laser burned into the disk to create a series on pits and areas not burned.

To read, a laser scans the disk if the laser hit a pit the light reflects back. A diode translates the impulses into binary.

Common type of secondary storage are optical disks, tape, diskette, Magnetic tape, CD or DVD

Keyboard

Mouse

Scanners

Speakers

Microphones

The OS takes over just after the computer wakes up and allows the computer to begin doing tasks.

Ex: Windows by Microsoft, Macintosh OS, UNIX/Linux

Early OS’s were command based. To save a file the user needed to know the word commands.

Now most computers use GUI, graphical user interface. ◦ A picture (icon) based program, where the mouse

is used to point and click on the function.

Is the most commonly used. Some PACS systems used a proprietary system.

UNIX is usually used on large servers because of the exceptional multitasking capabilities.

Soft copy = CRT or LCD display (Plasma screen) Hardcopy = film

Digital images are made of discrete picture elements, arranged in a matrix. The size of the image is described in the binary number system

Modern imaging systems are at least 1024 x 1024

4096 x 4096 is being developed for digital radiography. The number of pixels on a display determines the resolution.

PACS - Picture Archiving & Communications

System

DICOM - Digital Images & Communication in Medicine

TELERADIOGRAPHY -Remote Transmission of Images