GCSE Flashcards
Control unit
- manages data flow inside the CPU (to registers, ALU, cache) and outside the CPU (to main memory and input/output devices)
- decodes instructions
- it controls and coordinates the activities of the CPU in the fetch-decode-execute cycle
HDDS pros + cons
- High capacity —> up to several TB
- inexpensive —> compared to SSDs
- less durable than SSDs —> contain moving parts —> not so robust —> if dropped
- can be affected —> by magnetic fields + heat —> so requires expensive cooling systems —> less durable
- Fast + reliable —> means fewer repairs
- Slower than SSDs —> contains moving parts
HDDs pros + cons
- High capacity —> up to several TB
- inexpensive —> compared to SSDs
- less durable than SSDs —> contain moving parts —> not so robust —> if dropped
- can be affected —> by magnetic fields + heat —> so requires expensive cooling systems —> less durable
- Fast + reliable —> means fewer repairs
- Slower than SSDs —> contains moving parts
SSDs pros + cons:
- durable —> has no moving parts —> will be more robust when dropped
- reliable —> means fewer repairs
- portable + takes up little physical space —> due to no moving parts —> reducing the physical device size
- can be expensive
- creates little heat + has efficient power consumption —> therefore, doesn’t require —> expensive cooling systems
- high capacity
- high speed —> contains no moving parts
Optical pros + cons:
- highly portable + lightweight —> easy to post or carry
- cheap
- not so durable —> will degrade over time —> with exposure to sunlights —> + is also susceptible to scratches
- slowest speed
- low capacity —> 50GB for Blu-Ray Dual layer
Registers
super fast memory that can be accessed extremely quickly
it stores instructions, memory addresses and data
Cache
it is very fast memory - but slower than registers
used to store instructions or data that the CPU is likely to reuse
Increasing clock speed means
programs run faster
An application and document is saved on a drive. You click on the document to open it. What must happen first before the CPU can process the document?
The application needs to be loaded into RAM. The document needs to be loaded to RAM.
Effect of increasing the sample rate (frequency) or sample resolution (bit depth)
increases the quality
increases the file size
A 2-place shift to the right effect:
divides the number by 4
causes a loss of precision
How is MOP represented in ASCII
each character has its ASCII code stored in the order written
the ASCII code is converted into 8 bit binary
Network protocol
is a set of rules for communication
Layer
provides a division of network functionality
Advantages of layers
- layers are self-contained - allows developers to only concentrate on one aspect of the network
- layers can be edited and removed without affecting other layers - provides more manageable divisions of work
Clock speed
determines the number of instructions processed per second
CPU speed dependent on
cache size
clock speed
number of cores
PC performance improved by
RAM
GPU
CPU
hard disk (SSD or HDD)
Explain how multitasking works
All running programs or data are stored in the RAM
which is managed by the memory management of the OS
one program can be run at a time by the CPU
so each process is allocated CPU time by the OS
one the allocated time is ended, the process is paused
the CPU time is then given to another process
this happens so quickly that to the user, it appears that multiple processes are run simultaneously
