mistakes Flashcards
(82 cards)
Utility?
utility performs a specific task (1) and is usually
related to the upkeep of the system (1).
system software w one purpose
Examples of a utility include a virus checker
(1)/disk defragmenter
Hashing algo for files - what do we want?
Low chance of collision (i.e. different inputs giving
same output) (1 – AO1.2) to reduce risk of
different files being marked as the same
(1 – AO2.1).
Quick to calculate (1 – AO1.2) as lots of files need
to be hashed/needs to be quicker than a bitwise
comparison to make it worthwhile
(1 – AO2.1).
Provides a smaller output than input (1 – AO1.2)
so quicker to compare hashes than original data
array vs linked list
A linked list is a dynamic data structure (1)
whereas an array is static (1).
An array can have any element accessed directly
(i.e. random access) (1) whereas a linked list
needs to be traversed until the desired element is
found (1).
Contents of an array are stored contiguously in
memory (1) whereas the contents of a linked list
may not be (1).
CSS external not embedded?
Content and formatting are kept separate (1).
Changes can be made to the external style sheet
and affect the whole site (1) saving time (1) and
ensuring consistency (1). Stylesheets can be
changed for different themes, or different devices
Why do we check email at server and client side?
carried out client-side/in
browser (1) meaning address can be checked and
stopped prior to reaching server (1) reducing
unnecessary load on the server (1).
JavaScript can, however, be amended and
circumvented (1) therefore address must be
checked at the server to ensure this has not
happened (1).
Primary key
A field that has a unique value/a unique identifier
(1) for every record in that table (1) - in this case
VideoID (1).
SAY FIELD
class?
A template (1) defining methods and attributes (1)
used to make objects
inheritance?
class takes on the methods
(1) and attributes (1) of a parent class (1).
The inheriting class may override some of these
methods/attributes (1) and may have additional
extra methods and attributes of its own (1).
What is a linker? - why need it?
Links the main program to libraries
* ..can either include them in the final executable
code
* ..or get the executable code to point to the external
libraries
user running the program will not necessarily
have the library installed on their machine (1)
therefore the relevant code needs to be included
within the final executable (1) - it is the job of the
linker to combine this code (1).
memory for portable? magnetic vs ssd
Device is likely to undergo lots of sudden
movement (1 – AO1.2) magnetic hard drives can
be susceptible to damage if moved quickly (1 –
AO3.3) due to the head coming into contact with
the platter (1 – AO3.3) whereas flash memory has
no moving parts and so is not affected (1 –
AO3.3).
The device is likely to be small (1 – AO1.2) - hard
drives require enough space for their moving parts
(1 – AO3.3) whereas flash memory, having no
moving parts, requires much less space (1 –
AO3.3).
2sc over sign and m
not easily possible to carry out calculations
using sign and magnitude (1) whereas they will
work with two’s complement
operating system func?
user interface
control hardware (graphics etc)
platform which software can be run - apps
control access - different users can access + own data
LINK TO CONTEXT
company use open source?
core func there so just need to amend - save time + money
GPU over cpu?
CPUs are general purpose processors (1)
whereas GPUs are designed specifically for
graphics (1). And so likely to have built in
circuitry/instructions for common graphics
operations (1).
GPUs are able to perform an
instruction on multiple pieces of data at one time
(1) often we want to do this when processing
graphics (e.g. transforming points in a polygon or
shading pixels) (1) which means it can perform
transformations to onscreen graphics quicker than
a CPU
why might game not work on other console?
Different consoles will have different processors (1
– AO1.2) each with their own instruction sets (1 –
AO2.1) and word sizes
Different consoles have different operating
systems (1 – AO1.2) and so games may be
dependent on libraries in one operating system
that don’t exist in another (1 – AO2.1) or may
make different system calls
or on different media e.g give example or DRM to protect run on other ones
packet switching?
Data is split into chunks called packets (1 –
AO1.1)
which have labels (1 – AO1.1) including
address being sent to (1 – AO1.1) and order (1
– AO1.1). Each packet is sent on the most
convenient/avoidable route (1- AO1.2) meaning
they may arrive in a different order to which
they were sent (1 – AO1.2). Once packets
arrive at receiver they are reordered
non graphical use of gpu
Performing complex numerical calculations
* Calculations on matrices / vectors / multiple data at
the same time
* …e.g. modelling risk
explain pipelining 5
Concurrent processing of multiple instructions
* One instruction can be fetched while previous is
being decoded…
* And the one before is being executed.
* In case of a branch pipeline is flushed.
* Increases speed of execution
magnetic work?
Data stored by altering the magnetic field of a small
section of the tape or disk; one orientation represents a
binary value of 1, the opposite orientation represents a
binary value of 0. Written to using a read head.
Read head can then read the magnetic field and
retrieve the data.
These read and write heads move across the disk or
the tape moves under the heads.
SS work?
store data using semiconductors;
drives can be based on NAND Flash or DRAM. No
moving parts are required.
servers + backups?
Backup involves copying potentially large amounts of
data to and from storage devices at regular intervals.
Servers distribute data to client devices
Problems with flat file? - customer bookings
Only one customer entry allowed (because of key
field)
* …so would not be able to add second entry
* Customer data already present/would be repeated
* ….resulting in redundant data/wasted space
* …resulting in inconsistencies should changes be
made
Solve issue of flat file?
add 2nd table and split up _ for _
primary of orig used as field in new as foreign key
create 1-many r
What does html do
L defines the structure of a web page
* HTML defines the content of a web page
* Using tags (enclosed in <>)
