Memory and storage * Flashcards
What does primary storage contain?
RAM
ROM
registers
cache
What is primary storage used for?
holds the data and instructions which the CPU needs access to while a computer is running
Can the CPU access data quicker from primary or secondary storage?
primary
What does RAM do?
holds the operating system, programs and data in use by the CPU when the computer is running
Is RAM volatile or non-volatile?
volatile
Is RAM read and write or read only?
read and write
Is RAM larger or smaller?
larger
What does ROM do?
- holds the first instructions for when the computer is first turned on (bootstrap)
- programs may be stored in ROM in embedded systems
Is ROM volatile or non-volatile?
non-volatile
Is ROM read and write or read only?
read only
Is ROM larger or smaller?
smaller
What does volatile mean?
memory is lost when the power is switched off
What does non-volatile mean?
memory remains when the power is switched off
How many bits are there in a byte?
8 bits in a byte
How many bits in a nibble?
4 bits in a nibble
How many nibbles in a byte?
2 nibbles in a byte
How many bytes in a kilobyte?
1024 bytes (1000)
thousand bytes
How many bytes in a megabyte?
1,000,000 bytes
million bytes
How many bytes in a gigabyte?
1,000,000,000 bytes
bilion bytes
How many bytes in a terabyte?
1,000,000,000,000 bytes
trillion bytes
How do you convert from kilobytes to megabytes to gigabytes etc
multiply by 1000
Why is secondary storage needed?
needed because ROM is read only and RAM is volatile
What is secondary storage needed for?
- storage of programs and data when the power is turned off
- semi-permanent storage of data that can change
- backup of data files
- archive of data files
What are the three common types of storage?
- optical
- magnetic (HDD, tape)
- solid-state (SSD)
Give three points about optical storage
- low capacity
- slow to access data
- thin, lightweight and portable
Give four points about magnetic storage
- high storage capacity
- quick to access data
- has moving parts
- performs better if defragmented
Give eight points about solid-state storage
- medium storage capacity
- very quick to access data
- no moving parts, very reliable
- no noise
- low power
- no need to defragment
- limited number of read/write cycles
- expensive
Give eight points about solid-state storage
- medium storage capacity
- very quick to access data
- no moving parts, very reliable
- no noise
- low power
- no need to defragment
- limited number of read/write cycles
- expensive
When is virtual memory needed?
needed when there is not enough physical RAM to store open programs
Where is virtual memory held?
on the hard disk
When are programs transferred out of virtual memory?
when they are not currently executed
When are programs transferred back to RAM?
when they are needed
What are the six factors needed to decide which device to use given an aoolication?
- capacity
- speed
- portability
- durability
- reliability
- cost
What makes electronic components easier to manufacture, cheaper and more reliable
using just two states to store data
