Extra paper 1 Flashcards
Example of application package/software to do with databases
Database/DBMS
to store/query/sort data about
customers/staff/stock
Example of application package/software to do with documents
Word processor
to create documents / letters / invoices for
clients/staff
Example of application package/software to do with presentations
Presentation software
to create presentations for clients/staff
Example of application package/software to do with emails
Email software
for staff to communicate with each other or
with customers
Example of application package/software to do with graphics
Graphics manipulation
to produce adverts / images for sales
Example of application package/software to do with web
Web browser
to view websites to purchase materials/stock
// view competitor’s website
Drawbacks to closed source software
No access to source code
● Cannot modify//improve to meet business needs
● Cannot fix bugs
● (Usually) cost to purchase licences // licence
conditions to meet//ongoing fees
Avantages of LAN (remember to be specific and say printer)
Share hardware (e.g. printers)
● Share files
● Share Internet connection
● Centralised security
● Log on / access files from any machine on the
LAN
●
What can be centralised with LAN
Central maintenance
● Central backup / storage
● Central installation / update of programs
● Can monitor user activity
● Can control access levels // Centralised user
admin
Why is virtual storage well-suited for storing back ups
Stored away from the computer(s)/remote…
● … so in case of disaster, data is not also damaged
● All of the data (from multiple machines) can be
backed up at the same time
● Can be accessed from elsewhere / other machines
● Storage can be expanded as necessary//no limit on
size
● Speed of access is not a priority for a backup
● Can make recovery from another site easier
● No on site maintenance required
● Allows more local storage capacity for data
Another important advantage of storing back ups
No physical space needed for backup hardware
What does multi tasking OS do
Multi-tasking…
● …runs multiple programs at the same time
What does multi user OS do
Multi-user…
● … allows multiple users at the same time (must
be clear that candidate is not discussing an OS
that simply has multiple accounts)
What does distributed OS do
allows multiple computers to work together on
a single task
What does embedded OS do
Embedded…
● …has a dedicated/limited function
● …is read-only / cannot be changed
When are interrupts checked for
Start/end of each fde cycle
What happens if an interrupt is raised
contents of registers copied to
stack
What do flags do in link to interrupts
Flags are set to determine if interrupts are enabled /
disabled
What happens at end of interrupt
After interrupt complete, previous register values
restored back from stack
● Flag is reset
● If higher priority interrupt received during servicing of
interrupt…
● …this is added to stack and new interrupt dealt with
What is garbage collection
Removes data not needed anymore (memory management)
What do paging and segmentation do
Split up memory
When is virtual memory used
When RAM is almost full
What happens if RAM is full
applications cannot be
loaded
Why is memory management important
If not, RAM would rapidly run out and fill up
with unneeded data/instructions and so no new
applications could run
What is a page table
A page table is used to map page location which is
slower than a segmentation table
What type of fragmentation does paging cause
internal
What type of fragmentation does segmentation cause
External
Is virtual memory cheaper than RAM
yes
Advantage of paging over segmentation
Paging can be more effective because any free
memory space can be used to swap data in and out
whereas with segments, lots of space will sit unused
until a segment the right size is available
When can a segmentation error occur
Segmentation errors can cause memory leakage
which would cause the system to crash
How does memory management do security
Security issues – applications can only access
memory allocated to them so (for example) a
malicious application cannot access the memory
allocated to a banking app. Also when applications
are closed, data is removed before being reallocated
so that applications cannot see historic data
What is a stack underflow
happens when we try to pop (remove) an item from the stack, when nothing is actually there to remove
What is a stack overflow
a type of buffer overflow error that occurs when a computer program tries to use more memory space in the call stack than has been allocated to that stack.
What difference should you NOT NOT NOT state for an array and list
Do not talk about the contiguous/non contiguous nature of them
Difference between array and list 1
Array is of fixed/defined size // static
● List size can be changed // no defined size //
dynamic
● Array holds data of single data type
● List can hold data of multiple / different types
What does a tuple being immutable mean
Cannot be changed at run time
How are values accessed from linked lists
Go to the first position indicated by the start
pointer
● From the first position, read the next pointer
value…
● …follow this pointer value and access the data
item
Binary 0.1 or 10.
0.1
3 other advantages of two’s complement
Calculations are more easily performed on two’s
complement
No additional hardware is required in two’s
complement // Addition and subtraction are carried
out using only an adder
● Two’s complement has only one representation for 0
Assembly language and processor
Assembly language is likely to be specific to the
processor type used // is machine dependent
● HLL is portable // can be used for multiple
processor types // programmer can pick from a
number of HLLs and paradigms // is machine
independent
Assembly language and knowledge of the processor
Assembly language requires more knowledge of
the processor // allows direct control of the
processor
● HLL provides more abstraction // requires less
knowledge of the processor
Assmebly language and conversion
Assembly language is a one-to-one conversion
to machine code
● HLL may produce multiple lines of machine code
per line of code // one-to-many
Why may multi core processors not be faster
Some instructions may not be able to be run in
parallel
● An instruction may be dependent / waiting for other
instructions to be completed
● Other factors influence processing speed – clock
speed / cache / bottlenecks / etc
● Program / OS needs to be written to specifically use
multiple cores
Is Encryption one or two way
2 so can be reversed
Is hashing 2 or one way
1 so cannot be reversed
What does asymmetric encryption allow
Also possible to verify identity of sender / origin of
data using asymmetric encryption.
Why is asymmetric encryption useful for passwords
Hashing is useful for information (e.g. password) that
needs to be verified but does not need to be known
at any point; once hashed, it is impossible to return
to it.
Why is encryption useful for most data storage
Encryption useful for most data storage as anyone
hacking into the robot will not be able to
read/understand the data.
Why is hashing useful for passwords
Hashing is useful for data storage of password /
other items that need to be verified, hash of input
compared against hash stored to confirm
correctness.
Where is hashing not useful
Hashing is not useful for data that needs to be
returned to the user as impossible to return to.
Why is encryption useful for data transmission
Encryption useful for data transmission as data
intercepted cannot be decrypted without the key.
Actual name of copy right act
Copyright Designs and Patents Act
What does copyright act do
● Gives the author (the programmers)
ownership/copyright of the photographs
● …no need to apply // this is automatic
● Others cannot use/distribute // can be
prosecuted/fined for using/distributing…
● …without permission
● Permission can be granted / bought / licenced
For karnaugh maps what is important
Least amount of boxes to cover all 1s, biggest boxes possible
Prison sentence for not handing over keys to encrypted files
2 years
Another issue with RIPA
with more organisations using their powers
for minor offences such as detecting those lying
about their address to get children into a better
school or fly-tipping.
What is damping factor
The pageRank theory holds that an imaginary surfer who is randomly clicking on links will eventually stop clicking the probabilityat anyy step that the person will continue is a damping factor
How does the PageRank Formula work?
(1 - 0.85) + 0.85 x (Previous Page Rank / How many arrows going out of the page)
Disadvantages of virtual storage
Dont have control over how it is stored
What is a call stack
Data structure that stores information about the active subroutines of a computer program like local variables
What does agile methodoligies require
Skilled developers
Interrupts extra
Complete current FDE cycle, relevant ISR loaded, into program counter
First main point of spiral model
Analysing system requirements
Second main point of spiral model
Pinpointing and mitigating risks
Thirs point of spiral model
Development, testing and implementation
Final point of spiral model
Evaluating to inform next iteration
Why is spiral model only suited to large scale projects
If the project is too risky it is terminated, however hiring risk assessors is expensive which makes methodology suited to large
What does the opcode contain
Adressing mode and istrunction
LMC how do you store 10
TEN DAT 10
Branching lmc
BRP POSITIVE
POSITIVE LDA TEN
