Flashcards
3: Hardware
Cards in this deck (83)
- 1Computer system has to support which 3 major areas of operational capability?Porcessing of data
Storage of data
Input and output of data - 2What is a register? terrible defComponent within CPU has fastest access speed
- 3What category is each component under. Acess time, capacity, size and cost just say increasing or decreasing of: Register, cache memory, main memory, hard disk, auxillary storageaccess time increase (access time increases from register to auxilliary storage)
capcity increase
size increase
cost decrease
Register: processor component
cahce memory and main memory: primary storage
Hard disk and auxillary storage: secondary storage - 4What is directly accessibly by CPURam, Rom, cache
- 5What need to consider when choosing storage medium or device other than access time, capacity, size, cost? 5- integral - user can't normally access - then hard disk of ssd
- individual item that can be instered into a drive (part of system or can be connected) - flobby disk, optical or magnetic tape cartidge
-peripheral device - can be connected when needed: hard dirve, memory stick/card
-portable item: flash memory stick, flobby or optic disk
- remote from system - often used for backup: clound storage, magnetic tape - 6Give the options for data output 5screen display
hardcopy
virtual headset display
speaker
writing to storage devices - 7Give the options for data input 6keyboard
uer interaction - mouse
touch screen
game controller
scanner
micorphone
reading from storage device - 8What are embedded systems?a special-purpose computer encapsulated by a larger system.
- 9What are the disadvantages of embedded systems? 3- cant be easily programmed, memory space limited, usually only performs specific taks - SPECIAL PURPOSE
(must still contain a processor, memory and VO capability - if on one chip called microcontroller ie phones)
- if errors found after installation - new chip have to be manufactured to replace
- less likely to be rotected against unlawful action sthen general purpose systems more being installed iwth internet connection - IOT - 10Random Access Memory RAMVolatile memory that can be read from or written to any number of times.
- 11ROM Read only memorynon-volatile memory that cannot be written to but can be read from any number of times.
- 12How does speed and size coorolate between registers, cache, main memoryregisters - main memory speed higher at registers
size higher at main memory - 13Describe RAMcomponents that make up the main memory of a general-purpose computer system. ANy byte of data stored can be accessed without affecting the other bytes stored. Volatile - when computer system switched off, memory lost. Cne be read from or written to.
- 14What are the 2 types of RAM?Dynamic RAM DRAM
Static RAM SRAM - 15Describe DRAMconstructed from capacitors that leak electricity so need regular recharging to maintain identy of data stored. DRAm requires less electronic components per bit stored
- 16What are 2 adv of DRAM?DRAM cheapter to make and has higher density for data stored
- 17Describe SRAMconstructed from flip-flops that continue to store data indefinetely wheile computer system switched on.
- 18Give adv of SRAMprovides shorter access time / faster rate of access to stored data
- 19Describe ROMshares random access as RAM but cant be written to. Non - volatiele - data not .ost. In general purpose system most important use is storing bootstrap program -runs immediately when system switched on.
- 20What are hte 4 types of ROM and describe each1. Simplist - programs or data installed as part of manufacturing process, new chip if need dif content
2. Programmable ROM PROM- manufacture of chip supplies chips to a system builder which installs the program or data intot he chips - allows system builder to test samples of programmed chip before commiting whole batch to be programmed - after installed cnat be changed
3. Erasable PROM EPROM - more flexible - instaled program can be erased using UV light, and new program installed - usually requires chip to be removed from circuit.
4. Electrically Erasable PROM EEPROM-electronical signal removes data, chip can stay in cirucit but chip still read only - 21BufferA temporary storage created for data transmitted from one part of the system to another which functions as a queue.
- 22What is a device driver?software for any hardware device
- 23What are the 3 main types of secondary storage devices? Give examples of eachoptical storage ie DVD, CD, blueray
magnetic ie hard drives, tape drives
solid state ie sd, ssd, pen drives - 24Describe magnetic media how it worksInteraciton with magnetic medium is controlled by a read head and a write head. Although seperate devices the 2 heads are ombines in a read-write head - the 2 alternative states of magnetisation are 1 and 0. A read head uses basic laws of hphsyics that a state of magnetisation will effect an electircal property, write head uses reverse law
- 25What are the features of a hard disk? 6-more than one platter disk
-each platter has read-wirte head for each side
-platters spin in unison
-read-write heads attatched to actuator arms - allow heads to move over surfaces of platter
- motion of each read-write is syncronised with other heads
-cushion of air ensures had doesnt touch a platter surface - 26Describe a hard disk works. 11 exam question* The hard disk has one or more platters made of aluminium or glass.
* Each surface of the platter / disk is ferrous oxide which is capable of being magnetised.
* The platters / disks are mounted on a central spindle.
* The disks are rotated at high-speed.
* Each surface of the disk has a read / write head mounted on an arm positioned just above the surface.
* Electronic circuits control the movement of the arm and hence the heads.
* The surface of the platter / disk is divided into concentric tracks and sectors.
* One track in one sector is the basic unit of storage called a block.
* The data is encoded as a magnetic pattern for each block.
* When writing to disk, a variation in the current in the head produces a variation in magnetic field on the disk.
* When reading from disk, a variation in magnetic field produces a variation in current through the head. - 27Describe hard diskdata stored in conecntric (same center) tracks - each track consists of a sequence of bits these are formatted into sectors - each contains a defined number o bytes. Secotr becomes smallest unit of storage. As movement of heads syncrnised, same tracks on dif disks can have related data stored on them -accessible by just 1 movement of hte head. cylinder - colleciton of tracks.
- 28Hard disk how to store a file (hard drive considered to be direct-access-read-write device as any sector cna be chosen for reading or writing however data in a sector has to be in order)sufficient number of sectors have to be allocated but these may or may not be next to each other. As files are made, deleted or edited he use of sectors becomes fragmented which decreases performance of disk. A defragmentation program can reorganise the allocaiton of secotrs ot files to resotre performance.
- 29What are the problem with hard drives?length of track of disk gets larger as move from center - have to factor in desin or else less storage than capable.
- 30What are all the optic medias and what do each stand for? 5CD compact disk
DVD digital video or vesatile disk
BD blu-ray disk
CD-DA CD digital sudio
CD-RW CD read-write - 31What are the features for process of reading data from disk 7-optical disk has 1 spiral track running from intter to outter edge
- during operation, disk spins
- simultaneously laser moves accross - continously focused on spiral track
-track on surface has pits and lands
-laser beam reflected from surface of disk
-reflection from pit can be detected unlike lands
-dif in intensity of light detector receives is interprested as either 1 or 0 to allow binary code to be read from disk - 32Describe howo CD-RW and DVD-RW workreflective surfaces is a special alloy material. When data being written (burn process) to disk, the heat generated by absorption of laser light changes material to liquid depending on intesity. Material reverts to either a crystalline or amorphous solid form when cools - when disk read, laser light reflected from crystalline solid but not amorphous solid allowing coding of 1 or 0. Disk functions as direct-access device despoite only 1 track as can go forwards or backwards. Data formatted into secotrs along track.
- 33Disk storage capacity is dependent on how clos individual physical represenattions of a binary digit can get what are the 2 factors?speed of rotation
wavelength of light
shorter wavelength light can be better focused 0 why DVD can store more thatn CD but much less than bluray - 34Give what on diagram of hard disk driveactuator arm
read wirte read
platter
clynder
spihde (stick in middle) - 35What in single disk?block
track
sector - 36Describe Solid-state Mediabasis flash memory - semiconductor technology with NO moving parts. Circuits consist of arrays of transistors acting as memory cells. Most frequently used tech is NAND (basic circuitory resembles NAND logic gate) with memory cells connected in series. Writing and reading to memory handled by a NAND flash controller - blocks of memory cells can have all contents erased in a flash. Before data can be written to a block of cells in memory, data in block first has to be erased. Block consists of several pages of memory - when data read, single page of data can be read in 1 oepration. Most frequent use is memory card or USB flash drive (memory stick). In USB the fflash memory is in devie with memory chip connected to a standard USB connector. Removable data storage.
Hard disk / Solid state drive SSD - 37What are the advantages of SSD 4No spin up time
fast
random-access to data
less energy - 38What are the disadvantages of SSD 4high storage costs per gigabyte
lower drive capacities
relatively low write speed
wear levelling - 39Liquid-Crystal Dsiplay LCDA screen back-lit by light-emmitting diodes and with liquid crystal cells sandwiched between polarisers.
- 40Varying level of light emmitted from invididual sub-pixels allows full range of colors. What are the 2 techonolgoies to create a pixel?Cathode ray tube CRT
Flat Screens ie liquid-crystal display LD - 41Describe CRTno individual component for a pixel. Inner surface of screen is coverd with phosphor - emits light when electrons fall on it. Individual pixel is lit by controlling direction of electorn beam used. Color CRT displays have individaul red green and blue phosphors arrnged to create an array of pixels.
- 42Describe Flat screens: LCD and LEDsLCD screen has individal cells containing a liquid crystal to create each pixel. pixel matrix is illuminated by backlighting and each piel can affect hte transmission of this light the create the on-screen display. The back lighting is usually by light-emmitting diaodes LEds. Polarised light directed to pizel matrix and a furhter poxariser is placed betwen pixel matrix and screen. If a voltage is applied to an individual pixel cell the alignment of the liquid crystal molecules are affected - charges light so screen
- 43Give order of what in LCD screenPolariser
color filter
color filter glass
liquid crystal-voltage
TFT glass polariser-voltage
backlight - 44Describe VR headset2 eye piece - fed paried images from controlling system which when looked together looks in 3d. Images can be collected using specialised photogarphic techniques or 3D graphics package
- 45What are 2 hard-copy output of text?Inkjet printer
laser printer - 46Describe Inkjet PrinterSheet of paper fed in, printhead moves accross, depositing ink on paper, paper moved forward, happens again till page printed. Printhead has nozzles htat spray droplets onto paoper. Ink cartidges
- 47What are the steps for black and white printing for a laer printer. 91. drum given electrical charge
2. drum starts to revolve step by step
3. at each step a laser beam is directed by teh mirror and lens assembly to a sequence of positions accross widith of drum
4. at each position laser is either switched off to leave charge on drum or on to discharge position
5. process repeats till full-page electrstatic image made
6. drum coated with charged tono- only sticks to positions hwere drum been discharged
7. drum rolls over paper - initally given electric charge
8. paper is discharged hten passed through ehated rollers to fuse toner particles and seal image on paper
9. drum charged before process repeats on next page - 48Describe for color printer what are the 4 colors?seperate toners requred for colors and process has to take place for each color. colors created from: cyan, magenta, yellow and black - tech produces dots. Image quality depends on number of dots per inch and software cna contorl number of dots per pixel
- 49What are 3 advantages of inkjet printers?inexpensive to buy
good quality one offs
can print on media types e cds tshirts - 50What are 4 dsadvantages of inkjet printers?-frequent changes of ink cartidges
can be rather noisy
ink expesnive
small paper tray - 51What are 4 advantages of laser printers?larger tonner cartages
cheaper printing cost per page
faster printing speed
text-high quality - 52What are 5 disadvantages of laser printers?produces particualtes and ozone gas-health issues
maintanacne can be costly
phsycially larger
images lower quality
printer expensive - 53* if want more detail see after doing past paperssee cs GCSE book
- 54Describe hard-copy graphics output describe bitmpa or vector graphic print and 3D printersspecialised technical applications often requre mroe accurate on parer then file - vector graphic or bimap print. Use of graphics plotter. USes pens to write usually on large sheet of paper constrained by sprockets along q pair of sides. Sprockets can move paper up or down and pens can either be parked or in use.
Also use 3D printer. BD desgin created in CAD package - design split into layers - 3D printer uses nozzle to squirt material on printer bed to create physical layer - repeated for layers. When whole object formed it has to be cured to ensure layssers stick together and material been converted to form requred - tech versatile - 55What are the Input devices provided for a user of a general purpoe computer system? 3keyboard
screen
touch screens - 56Describe keyboards - how works(key press immediately transfers character to computer screen). Key press converted to character code - to processor. Processor under control of OS, ensures text on screen. Keyboard has electrical circulator with own microporcessor and ROM chip.
-keys positioed above a key matrix-consits of set of rows of wires and another set of coloms of wires
-pressing a key causes contact at one of points where wires corrss
-microporcssor continously tests if any electrical circuit involving row and colom wire closed
-microporcessor can identif particular intersection causing this close
-processor uses data stored in ROM to identify character code related to key associated with intersection adn sends to screen - 57Describe the screenGraphical user interface GUI - provides dif screen icons - allows user to control data input - needs pointing mechanism ie mouse controls curser
- 58Describe Touch Screens: descrieb CRT screens or flat screensearly versions used CRT screens or flat screens - required emmiters to be positioned on sides of screen and detectors positioned opposite of them. Emmitters produced either infraed light or ultrasonic waves when finger blocked one of them detectors could measure reduced siganls
- 59Touch screens modern vesion has layers providing light output by display with touch-detecting layers added beneath surface of screen. What are the 2 approaches?Resistive touch screeen
Capacitive touch screen
In any type, processor takes readings form measuring devices and uses to calculate position of touch - allows processot to set in motion what action user requesting - 60Resistive Touch ScreenA flexible surface that causes contact between electrically resistive layers beneath when touched.
- 61Capactive Touch ScreenA rigid surface above a conductive layer that undergoes a change in electrical state when a finger touches the screen.
- 62Describe resistive touch screnshas 2 layers seperated by thin space beneath screen. Screen isn't rigid so when finger presses on screen the pressure moves top most of these 2 seperated layers so top layer makes contact with second. Point of contaft creates a voltage devider in horizontal and vertical directions
- 63Describe Capactive touch screenmakes use of fact that a finger touching glass screen can cuase capacitance change in a circuit component immediately below screen. Most effective tech is Projective capacity touch PCT with mutual capacitance. PCT screens have cirucit beneath containing an array of capacitors - can detec touch of several fingertips at same time
- 64What are the ways to Input a graphic? 3several ways to store and use image data in a computer ie webcam, digital camera, scanner
- 65Describe a scannerreverses printing process - takes image and creates digital representaiton from it. paper held in fixed psoition and a light source moves from 1 end of sheet to toerh, covers width. Re reflected light is directed by a system of mirrors and lenses onto a charge - coupled device CCD
- 66What are 3 aspects of CCDconsits of an array of photo-sensitve cells
-produces an electrical response propotional to light intestity for each cell
-needs an ACD converter to create digital values to be transmitted to computer. - 67What use for voice input and describemicrophone: has a diaphragm, a flexible material that vibrates by incoming sound. If diaphragm connected to suitable circuitry the vibration cuases change in an electrical signal. A condesnser microphone uses capacitance change as the mechnaism or piezoelectric crystal. Analogue electrical signal is converted to a digital signal by ADC converor so can be processed indie computer.
- 68What use for sound output and describespeader - DAC. Analogue signal fed as varying electrical current to speaker. Current flows through a coil suspended within the magnetic fideld braded by a pernament magnet in the speaker. As size and direction of current keeps changin, coil moves backwards and forwards. Movement controls movement of diagphragym - cuases sound to be reated.
(input and output controlled by a soundor audio card install in computer) - 69what are the main primary storage?RAM
ROM - 70What are the adv and dis of storing data magnetically? 3 adv 3 dis- magnetic media reliable and tends to last for long time
-low costs per unit capacity
-can store large quantity of data in compact way
-not robust, tends to break on impact or during vibrations
-high number of moving parts - makes media slow to access - 71How does optical storage work?each 1 or 0 is represented as a microscopic hole (pit) or a flat surface (land) on surface of disk.
A laster is shone on the disk surface
if laser hits a land will be reflected into sensore. If laser hits pit will be reflected elsewehere - can represent 1 or 0 - 72Give adv 2 and dis of 3 optical mediagreat reliability waterproof and shockproof - makes ideal for portability.
- low costs
-low capacity - cheap though so can buy many
-access time slow as parts in optical media drive have o move to find right bit of data on disk
- writing to disk can be slow process - 73What are the dis of virtual memory?-can have negative impacts on performance and health on SSDs
-limited space in secondary storage - 74How does Virtual memory work?paging: memory can be split into sections called pages. Works by moving these pages between RAM and secondary storage.
-if page not being used may want to put it into virtal memoyr. When page moved to HDD, put into a special file called page file. OTher processes can then use memory that just freed in RAM.
When want to use page again, first need to move back to RAM. Do this by swapping page want tiwht one already in RAM. - 75Give some examples of client-server applications 7printer
file sharing
prozy server
email server
database server
domain controller server: management of user accounts ie ids and passwords, client sends login request to server which processes and grands request if user ID and pass recognised - 76Describe router role in a network 5connects 2 networks together which ma operate on dif protocols
allows internal connections between LAND or allows external connection fromr main LAN to a WAn
acts as gateway and firewall
usually attached to server or switch in LAN
router translates private IP addresses to public IP addresses and vice versa - 77SRAM vs DRAM 4SRAM: doesnt need to refrsh hence uses less power nad faster access time. More complex cirutity so more $. Each bit stored in flip-flop. Lower data density. Used in cache memory.
DRAM: has to be refreshed, so slower access times and needs higher power. Only single transisotr and capacitor, less expensive to purchase. Each bit stored as charge. Higher data density. Used in main memory. - 78Give dif between PROM EPROM and EEPROMProm can be programmed only once after created and data cannot be erased or deleted
EPROM: can be erased by UV light exposer and then reprogrammed. Chip has to be removed for reporgramming.
EEPROM: can be erased by electrical signal and then reprogrammed. Can update data without removing chip - 79identify 3 functions of a routerTo receive packets from devices or the Internet
• To forward / route packets to the destination
• To find the destination of the packet
• To assign / allocate private IP addresses to devices on LAN
• To store / update / maintain a routing table
• To find the most efficient path to the destination
• To maintain a table of MAC and IP addresse - 80Give 3 lossy methods to compress an image• Reduce bit depth
• ... reduces the number of bits per colour / pixel which means each pixel
has fewer bits
• Reduce colour palette // reduce number of colours
• ... fewer colours mean fewer bits needed to store each colour
• Reduce image resolution
• ... fewer pixels per unit measurement means less binary to store - 81Give purspose and contents of the data dictionary in the DBMS• Stores metadata about the database
e.g.
• field / attribute names
• table name
• validation rules
• data types
• primary keys // foreign keys
• relationships - 82Describe the file management tasks that an OS performs• Storage space is divided into file allocation units
• Space is allocated to particular files
• Maintains / creates directory structures
• Specifies the logical method of file storage (e.g. FAT or NTFS)
• Provides file naming conventions
• Controls access // implements access rights // implements password
protection // Makes file sharing possible
• Specifies tasks that can be performed on a file (e.g. open, close, delete,
copy, create, move etc.) - 83Identify 2-4 utility programs that can be used to imporve the performance of a computer and state how they improve the performance• Defragmentation
• Less time is taken to access files because each one is contiguous so
there is less head movement
• Virus checker
• makes more RAM available for programs to run
• ... because it removes software that might be taking up memory /
replicating
• Disk repair / Disk contents analysis
• preventing bad sectors being used because it identifies / marks them
• reduces access times by optimising storage
• Disk/system clean up
• releases storage by removing unwanted / temporary files
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- A Level AS Computer Science (Unit 1: Theory Fundamentals) Flashcards on 3: Hardware, created by HRYN red on 23/11/2016.
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