TexPREP Summer Camp Computer Science Computer Systems TexPREP Summer Camp Computer Science

Computer System Hardware Computer System Software All those parts of a computer that you can see and touch. Programs (set of instructions) and data.

Hardware Computer http://www.antonine-education.co.uk/ict_as/ict_module_2/topic_8/computer_architecture.htm

Hardware The two most important components of a computer are: CPU: Central Processing Unit Memory: typically RAM (Random Access Memory) They are connected by the system bus and are located on the motherboard.

Motherboard http://www.nitroware.net/reviews/206-mainstream-computing-showdown-amd-a6-v-intel-i3?start=3

CPU The CPU is the “brain” of the computer. It gets an instruction from main memory and then executes it. If the instruction needs some data, it gets the data from main memory in order to process it. After executing the instruction, if there is a result that needs to be saved, it stores the result on main memory. These steps are repeated for each instruction in the program. The speed of the processor is expressed in Gigahertz (GHz).

Memory There are different types of memory in a computer system. Main memory (RAM): where programs and data must be loaded in order to be processed. ROM: where the boot (startup) program is stored. Cache: very high speed memory used to improve the performance of the system. The amount of memory is typically expressed in Megabytes (MB), Gigabytes (GB), or Terabytes (TB). RAM and Cache are volatile, that is, they lose their content when the power is turned off. ROM is not volatile. Their access time is in the order of nanoseconds (0.000000001 seconds)

System Clock The components of the computer must interact in a synchronized way. A system clock is used to control the timing of all computer operations. It generates regular “ticks” (electronic pulses) that set the operating pace of the components. Its speed is expressed in Megahertz (MHz) or Gigahertz (GHz).

Peripheral devices Storage devices: used to store data and programs permanently (non volatile). For example: hard drive, flash drive, cd drive, etc. Input devices: used to enter data and instructions (programs, commands, etc.) into the computer. For example: keyboard, mouse, microphone, scanner, etc. Output devices: used to get information from the computer. For example: monitor, printer, speakers, etc.

Storage devices The three main technologies are: Magnetic: used on hard disks, tape, etc. Optical: used on CDs (ROM, R, RW), DVDs (R, RW, RAM), etc. Solid state: used on flash drives, memory cards, etc.

Hard drive http://www.pctechguide.com/31HardDisk_Construction.htm

Optical Discs laser diode prism light- sensing diode 1 lens pit land 1 lens pit land disc label Step 3. Reflected light is deflected to a light-sensing diode, which sends digital signals of 1 to computer. Absence of reflected light is read as digital signal of 0. Step 2. If light strikes a pit, it scatters. If light strikes a land, it is reflected back toward diode. Step 1. Laser diode shines a light beam toward disc. Discovering Computers 2006, Course Technology, p. 367 Fig. 7-20

Adapter Cards Also known as expansion boards, are used to increase the capabilities of a computer. They must be inserted in expansion slots and their respective device drivers installed before they can be accessed by the system. There are different technologies: PCI, AGP, etc.

Adapter Cards examples video adapters graphics accelerators sound cards accelerator boards NIC - network interface card

Graphics Adapter Card http://salestores.com/stores/images/images_747/P65MDDE128LPUF.jpg

Units of measurement KILO: 1,000 or 103 MEGA: 1,000,000 or 106 GIGA: 1,000,000,000 or 109 TERA: 1,000,000,000,000 or 1012

Digital Representation Inside the computer… Everything is discrete (digital), not continuous (analog) – i.e, it must be represented using a discrete (number) value Problem: How do we put the analog world “inside” the digital computer? Solution: Devise ways to represent real-world, analog data in digital forms

What do computers work with internally? Computers have storage units called binary digits or bits The computer operates with voltage through what amounts to microscopic switches that are either “On” (1) or “Off” (0) Low Voltage = 0 High Voltage = 1 all bits have value 0 or 1

Representing Numbers Binary number system

Representing Characters ASCII (American Standard Code for Information Interchange) and Unicode