- •Хакасский государственный университет
- •Part II Texts for Supplementary Reading
- •Предисловие
- •The main parts of the computer
- •Using a mouse
- •Lesson 2
- •Word-building (словообразование) (1)
- •Keyboard
- •Windows program keyboard shortcuts
- •Lesson 3
- •Buses and interfaces
- •Word-building (2)
- •Lesson 4
- •Structure (phrases)
- •A) “hardware”
- •B) “data”
- •Lesson 5
- •What is a microprocessor?
- •Pentium, pentium pro, pentium II and pentium III
- •Lesson 6
- •Word-building (3)
- •Lesson 7
- •General dram concepts
- •Structure ( 2)
- •Lesson 8
- •Storage media
- •Word-building (4)
- •Incompatible, unrecoverable, unavailable, unusable, unsuitable, non-removable, non-contiguous, non-volatile.
- •Structure (3)
- •Lesson 9
- •«Ware» terms
- •Section II. Software lesson 10
- •Structure (4) Ex.2 a) Read the sentences and analyze their structure:
- •Programming language generations
- •Lesson 11
- •Word-building (5)
- •What is object-oriented software?
- •Inheritance
- •Object-oriented languages
- •Lesson 12
- •General operating system concepts
- •Wysiwyg – structure (5)
- •Imperative sentences (commands and instructions) :
- •Starting and quitting windows nt
- •2.Using the desktop
- •Ex.5 Translate into English:
- •Ex.6 Say a few words about:
- •Revision (sructure)
- •Lesson 14
- •Ex.3 Translate into English:
- •Config.Sys commands
- •Ex.6 Agree or disagree:
- •Lesson 15
- •Ex.1 Translate the following technologies into Russian:
- •Ex.2 a) Read and translate into Russian:
- •Ex.5 Read and translate into Russian: operating system overview
- •Operating systems and file systems
- •Lesson 16
- •General database concepts
- •Ex.4 Choose the right synonym to the word ‘query’: a) requirement; b) retrieval; c) request.
- •Section III. Networking lesson 17
- •What is a network?
- •How are networks categorized?
- •How does p2p work?
- •Information transmission media
- •Lesson 18
- •Computing network components
- •Ex.10 Read and translate into Russian:
- •Ex.11 Translate into English:
- •Lesson 19
- •The internet
- •Internet protocols
- •Surfing The Net. By Shirley.
- •Lesson 20
- •Basic security and licensing terms
- •How bytes and bits work
- •System case
- •How pci works
- •Motherboard and system devices
- •Graphics adapter
- •How it works
- •System cache
- •Ethernet
- •Traditional ethernet
- •Fast ethernet
- •Gigabit ethernet
- •How a computer virus works
- •General virus types
- •All maliicous codes aren’t viruses
- •Intel software license agreement (Final, Single User) (abstract)
- •Glossary
- •Defragment
- •Device Driver
- •Formatting
- •Operating system
- •Plug-n-Play
- •Program
- •Vesa Local Bus
- •Virtual Memory
- •It Crossword Puzzle
- •Answer keys
- •It Crossword Puzzle
- •List of acronyms and abbreviations
- •1. Terms used in computer field
- •2. Basic abbreviations used in scientific field
- •3.Irregular verbs
- •Bibliography Основная литература
- •Справочная литература
How it works
The CPU in your PC actually contains three parts:
Input/Output Unit (I/O Unit)
Arithmetic/Logic Unit (ALU)
Control Unit
The I/O unit controls interaction between the CPU and all the other parts of your computer. The ALU handles logic and math functions. The control unit basically tells the other parts of the CPU what to do.
Like all things computer, the CPU understands instructions only in terms of ones and zeroes at the core. A change in the electrical signal through a given circuit changes that circuit from a one to a zero or vice versa. When a programmer compiles some code s/he has written, that code is translated into machine language that the CPU can understand.
System cache
The system cache is responsible for a great deal of the system performance improvement of today's PCs. The cache is a buffer of sorts between the very fast processor and the relatively slow memory that serves it. (The memory is not really slow, it's just that the processor is much faster.) The presence of the cache allows the processor to do its work while waiting for memory far less often than it otherwise would.
There are in fact several different "layers" of cache in a modern PC, each acting as a buffer for recently-used information to improve performance, but when "the cache" is mentioned without qualifiers, it normally refers to the "secondary" or "level 2" cache that is placed between the processor and system RAM.
“LAYERS” OF CACHE
There are in fact many layers of cache in a modern PC. This does not even include looking at caches included on some peripherals, such as hard disks. Each layer is closer to the processor and faster than the layer below it. Each layer also caches the layers below it, due to its increased speed relative to the lower levels:
-
Level
Devices Cached
Level 1 Cache
Level 2 Cache, System RAM, Hard Disk / CD-ROM
Level 2 Cache
System RAM, Hard Disk / CD-ROM
System RAM
Hard Disk / CD-ROM
Hard Disk / CD-ROM
--
What happens in general terms is this. The processor requests a piece of information. The first place it looks is in the level 1 cache, since it is the fastest. If it finds it there (called a hit on the cache), great; it uses it with no performance delay. If not, it's a miss and the level 2 cache is searched. If it finds it there (level 2 "hit"), it is able to carry on with relatively little delay. Otherwise, it must issue a request to read it from the system RAM. The system RAM may in turn either have the information available or have to get it from the still slower hard disk or CD-ROM.
It is important to realize just how slow some of these devices are compared to the processor. Even the fastest hard disks have an access time measuring around 10 milliseconds. If it has to wait 10 milliseconds, a 200 MHz processor will waste 2 million clock cycles! And CD-ROMs are generally at least 10 times slower. This is why using caches to avoid accesses to these slow devices is so crucial.
Caching actually goes even beyond the level of the hardware. For example, your web browser uses caching itself, in fact, two levels of caching! Since loading a web page over the Internet is very slow for most people, the browser will hold recently-accessed pages to save it having to re-access them. It checks first in its memory cache and then in its disk cache to see if it already has a copy of the page you want. Only if it does not find the page will it actually go to the Internet to retrieve it.