 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.

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

 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 millions of times in a second. Each 1 or 0 is 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