cs CPU architecture Flashcards
1
Q
purpose of ALU
A
resposible for any arithmetic or logic processing that might be needed when a program is running
2
Q
purpose of control unit
A
- To control operation of fetch-execute cycle;
- To send control signals/commands to other components of fetch-execute cycle;
- To control the transfer of data between registers
3
Q
The internal clock
A
controls the cycles inside the processor and its frequency is called clock speed
4
Q
immediate access memory
A
Immediate Access Store holds all the data / instructions / programs currently in use
- Immediate Access Store is volatile memory
- Immediate Access Store has fast access times
5
Q
system clock
A
- synchronise operations
- … by creating timing signals
6
Q
program counter
A
Stores the address where the next instruction is to be read from
7
Q
memory address register
A
Stores the address of the memory location currently being read from
8
Q
memory data register
A
Holds the data/instruction which has been read from the address in the MAR.
9
Q
current instruction register
A
Holds the instruction currently being decoded and/or executed
10
Q
index register (IX)
A
Stores a value; only used for indexed addressing.
11
Q
status register
A
Holds information about the current state of operations. It is used to set flags or to detect error conditions and to disable/enable interrupts.
12
Q
fetch
A
The address of the next instruction to be executed, held in the PC, is copied to the MAR.
- The instruction held at that address is placed in the MDR. then copied to CIR
13
Q
decode, execute
A
The instruction is held in the CIR.
- The control unit decoder decodes the instruction, the opcode identifies the type of instruction it is and the relevant part of processor executes the instruction.
14
Q
what is the stored program concept
A
Instructions and data are stored in the same memory space / in main memory.
15
Q
control bus
A
The control bus is bi-directional and carries control signals.
16
Q
data bus
A
The data bus is bi-directional as data can be sent both ways along the bus
17
Q
address bus
A
This bus carries the address of a memory location in one direction
18
Q
how number of cores affect performnace
A
Each core processes one instruction per clock pulse
- More/multiple cores mean that sequences of instructions can be split between them
19
Q
how clock speed affects performance
A
- determines the number of cycles the CPU can execute per second
- increasing clock speed increases the number of operations/number of fetch-execute cycles that can be carried out per unit of time
20
Q
how cache affects performance
A
cache memory is faster than main memory so the more that can be stored in cache memory the less frequently the main memory needs to be accessed
- … the higher capacity the more frequently used instructions it can store for fast access
21
Q
what are interrupts
A
- A digital signal from some device/source seeking the attention of the processor
- a signal from a device/program that it requires attention from the processor.
22
Q
how interrupts are handled
A
Detection: At the start / end of each fetch-execute cycle the processor checks for interrupt(s)
- Check if an interrupt flag is set // Check if bit set in interrupt register
- Processor identifies source of interrupt
- Processor checks priority of interrupt
- If interrupt priority is high enough // Lower priority interrupts are disabled
23
Q
def of file header
A
specifies the image size, number of colours, and other data needed to display an image
24
Q
benefits of vector graphic
A
can be enlarged without loss of quality
generally a smaller file size
25
bitmap vs vector
bitmap is made out of pixels, vector store set of instructions
bitmap file is usually bigger
26
sampling resolution
number of bits used to store each sample
27
benefits of connecting to a LAN
allows sharing of files
allows sharing of resources
28
what is a client server model
at least one computer as the server,another as the client
29
benefits of client server model
files are centralised
centralised back up
centralised security
30
pros/cons of star topology
pros :signals only go to destination
centralised management
cons:
if central device fails whole network goes down
performance id dependant on central device
31
pros / cons of bus topology
pros:
easier to set up
less cable required
cons:
increased risk of collisions
weaker security
32
what is mesh topology
all computers are connected to at least one other device
multiple routes between devices
33
benefits of mesh topology
if on eline goes down there are other routes
improved security as not only using one line
fewer collisions
34
difference between fibre optic and copper cables
fibre optic data is transmitted by light, copper by electric signals
fibre optic has greater bandwidth
fibre has higher transmission rates
35
benefits of upgrading to fibre optic cable
less interference with the signal
more secure
greater bandwidth
36
wired vs wireless connection
wired : faster connection, more reliable, more secure
wireless:freedom of movement, less cabling
37
how a switch supports a LAN
allows connection between two or more devices
connects individual devices together
38
wireless access point supports LAN
allow communication of devices
allow wireless enabled devices to connect to a wired network
39
how a bridge supports a LAN
to connect 2 LANS
transmit data between 2 networks with the same protocol
40
function of router
receive packets from devices
find destination of packets using IP address
forward packets to destination
41
what is bit streaming
sequence of digital bits
over a communucation path
requires some buffering
tranfers data at high speed
42
how a 3d printer works
the CAD software splits objects into pieces
data is sent to the printer
the plastic is melted and transferred to the nozzle
43
how a laser printer works
revolving drum is given an initial charge
a laser beam scans across the drum
discharging certain points
44
explain the internal operation of a speaker
translates electrical signal into physical vibrations
an electric current in the coil creates an electro-magnetic field
45
describe the internal operation of optical disk
drive motor is used to spin the disk
tracking mechanism moves the laser assembly
a lens focuses the laser onto the disk
46
features of SSD
no moving parts
non-volatile
makes use of blocks/arrays
47
how a magnetic hard disk works
binary digits are represented by spots on disk
disk made up of platters
disk divided into tracks and sectors
48
resistive touchscreens
two layers with a gap
when a finger touches the screen the layers touch
and the contact point is calculated
49
capacitive touchscreens
made up of glass layers
the screen stores electrical energy
screen can be touched in multiple places at once
50
infrared touchscreens
use a grid pattern of LEDs
when touched, the grid is interupted and the position is calculated by a microprossesor
51
surface acoustic wave screens
made use of ultrasonic sound waves
the position of the touch is detected by a reduction in sound wave amplitude
52
differences between SRAM and DRAM
DRAM has to be refreshed, SRAM does not
DRAM store each bit as a charge, SRAM each bit is stored using a flip flop
SRAM has faster access time
53
how interupts are handled (long answer)
detected at start and end of each FDE cycle
check if interupt flag is set
processor checks source and priority of interrupt
disables lower priority interrupts
54
def of interrupts
signal from a device seeking attention from the processor
55
examples of hardware interrupts
user prssed key on keyboard
printer out of paper
56
adv of library routines
code is already tested so it is more liekly to work
saves programming time
57
what is meant by a dynamic link library(DDL)
collection of programs that are already compiled
linked to main program during execution
58
benefits to programmer of creating a DDL
memory requirements for program is reduced
the executable file size will be smaller
59
assembler
assembly language to machine code
converts mnemonic to binary equivalent
60
compiler
attempts to translate whole source code
creates error report at end of translation
creates an executable file
61
interpreter
interprets each line individually
translated one line at a time
execution is slower
debugging is easier
62
features of a IDE
context sensitive prompts- suggests the code to add
single-stepping- run code one line at a time to check values
breakpoints- stops program at a specific point to check for errors in a specific part of the code
pretty print
report window
63
anti virus software
scans for malicious software
deletes any malicious software found
prevents downloading of viruses
64
phishing
the email pretends to be real
asking users to give private information
65
pharming
malicious code that redirects to fake website
aim to obtain personal info
uses false representation of official organisation
uses fake websites
66
explain how a digital signature is used to authenticate document
the sender uses a hash algorithm
to produce a message digest
sender encrypts the digest to create the digital signature
receiver decrypts signature to produce digest
receiver uses same hash algorithm to produce a regenerated message digest
compares the message digests
if same then it is authentic
67
validation
checks whether data is reasonable
68
verification
checks if data entered is same as original
69
parity check
uses even or odd parity
each byte has a parity bit
parity bit is either 0 or 1
after transmission it is re checked
70
checksum
a calc is carried out on the data to be sent
the result is sent
checksum is recalculated at receiver
if both are same no error has occured
71
def of ethics
system of moral principles
that guide decision making
72
limitations of a flat file database
data redundancy
data dependency
lack of data integrity
lack of data privacy
73
why use relational database
reduces data redundancy because linked tables mean that each data item is stored only once
74
1nf,2nf,3nf
1nf- no repeating groups of data
2nf- no partial key dependencies
3nf- no non-key dependencies
75
what is meant by ethernet
a protocol for data transmission over a wired connection, data is transmitted in frames
76
what is a data dictionary
metadata about a database
77
what is a query processor
sotware that allows user to enter criteria, then finds appropriate result
78
what is a developer interface
a software tool that allows the user to create items such as tables, and reports
79
what is a logical schema
a model of a database that is not specific to one DBMS
80
direct addressing
when the operand holds the memory address of the data
81
indirect addressing
when the operand holds a memory address that stores the memory address of the data
82
immediate addressing
when the operand is the data
83
types of signal a control bus can transfer
read/write
interrupt
84
how data is transmitted through a USB
a bit at a time
85
process management by the OS
manages scheduling of processes
manages which resources the processes require, such as alocating memory
enables processes to share data
handles the process queue
86
purpose of utility software
help user set up computer, by checking for faults
87
define program library
pre-existing subroutines that can be used in coding by importing them into the main code
88
difference between ROM,EPROM,EEPROM
EPROM needs to be removed from device, EEPROM can be erased without
EPROM can be erased using UV light, EEPROM can be erased using voltage
PROM cant be reprogrammed, others can
89
key management tasks that the OS performs
file management
security management
process management
memory management
90
logical right shift math
division
91
how a hardware interrupt is handled
(Key press example)
a check is done at the start and end of every F-E cycle.
processor checks source and priority of the interrupt
system checks the interrupt register for higher priority interrupts
the appropriate ISR is called
the input data from the key press is processed
92
transfer notation of F-E cycle
MAR <- [pc]
PC <- [PC] +1
MDR <- [[MAR]]
CIR <- [MDR]
93
Why adding another core may not double the speed of the computer
Software may not support dual-core processing, so one core is left idle
memory access speed may not match speed of cores which causes delay
multiple cores introduce additional overheads because of the need of communication between devices
94
sampling def
amplitude of soundwave taken at different points in time
95
sampling rate def
the number of samples taken per unit of time
95
Sampling resolution def
number of bits used to store each sample
96
drawing list def
the list of shapes involved in the image
97
property def
data about the shapes
98
colour depth def
number of bits used to represent the colour of a single pixel
99
how sound is represented on a computer
the amplitude is recorded a set number of times per second
each amplitude is given a corresponding binary number
100
how sampling is used to record sound clips
the amplitude of the wave is determined
at set intervals
to get an approximation of the sound wave
101
what is cloud computing
accessing a service on a remote server
102
what is a privatecloud
computing services offered either over the internet or a private internal network
only available to select users not the public
103
what is public cloud
computing services offered by third party provider over the internet
is available to anyone
104
adv and disadv of cloud computing
adv- can be free (for small quantities), security could be better, data can be easily shared
disadv- can only access via internet connection, no control over security, no control over backups
105
description of a WNIC
hardware component that allows a device to connect to a wireless network
106
repeater description
restores the digital signature so it can be transmitted over greater distances
107
internal operation of a microphone
microphone has a ribbon
incoming sound waves cause vibrations of the ribbon
causing a coil to move past a magnet
producing an electrical signal
108
describe role of an actuator
generates a signal that converts electrical energy into an mechanical force
109
what happens on first pass
read the assembly language program one line at a time
ignore anything not required
data items are converted into binary equivalent
110
second pass
read assembly language one line at a time
forward references are resolved
any symbolic address is replaced by absolute address
111
how OS manages peripherals
installs device drivers
to allow communication between peripherals and computer
sends and receives data to and from peripherals
112
defraggmentation software
makes files occupy contiguous blocks, improves disk access time
113
disk analysis/repair software-
scans a hard disk to identify bad sectors
114
disk formatter
prepares a hard disk for first use
115
commercial software licsense
user has to pay for the product so the programmer can gain an income
enables product to be copyrighted
116
shareware licsense
enables program to be copyrighted
user cannot legally edit the program so the developer retains control of product
117
file management
creates files and folders
renames files and folders
118
memory management tasks
allocates RAM to blocks
keeps track of allocated locations
handles virtual memory
paging
119
security management
set up users accounts
checks usernames, passwords
implements access rights
120
