Primary memory is built inside the computer.
Non-volatile memory keeps data even if computer is switched off, whereas volatile memory loses
data when switched off
ROM (read only memory) – cannot be written to, CAN BE READ FROM
Very useful for storing instructions and data
BIOS is stored in ROM – checking that the hardware is functioning correctly and it runs the bootstrap
program to load the OS from the hard drive into RAM
RAM is random access memory:
It can be stored or accessed form any location
It holds the OS and running programs. It is easily upgraded and can be overwritten.
Secondary storage is need for:
Storage of programs and data when the power is turned off
Semi-permanent storage of data which can be changed
Backup of data file
Archive of data files
Flash memory – non-volatile memory that can be read from or written to. It is secondary storage
Bit - 1 bit
Nibble – 4 bits
Byte – 8 bits
Kilobyte – 1000 bytes
Megabyte – 1000 kilobytes
Gigabyte – 1000 megabytes
Terabyte – 1000 gigabytes
One letter – one byte
Email – 2KB
GIF – 12KB
RAW photo – 11.4 MB
Audio file (3 min) – 3MB
Uncompressed audio file – 15MB
File – 4GB
200 tiny photographs – 1.2GB
Optical – read-only, large scale distribution, small capacity
Magnetic – low cost, high capacity, cloud storage on server farms, reasonably good access
SSD – high cost, high capacity, fast access, cloud storage on server farms, very expensive, finite
number of read/write cycles, no moving parts (more reliable), more durable (no attraction to
magnetic fields)
, Drive – device that reads from or writes data from secondary storage
Media – what data is stored on
Optical – CD-R, CD-RW, DVD-R, DVD-RW, Blue _Ray
Pros: Cheap, lightweight, portable
Cons: slow access times, prone to scratches and it has the lowest data carrying capacity
Magnetic: HDDS, tapes
Pros: cheap, large capacity, quicker access times
Cons: fragile, not very reliable or durable
SDD:
Pros: Durable, fast access times, reliable, durable, low power consumption, no noise
Cons: Finite number of read/write cycles, expensive
The need and purpose of primary storage is to hold both data and programs that
are in current use by the CPU.
Primary storage devices are extremely fast and so the CPU can run at top speed.
Main memory does include Rom but it is the only type of non-volatile memory
RAM is used as main memory. It acts as a temporary store for program
instructions and data. It can only store things temporarily because it is volatile -
it must constantly be powered or it will lose any data it is holding. It can be
accessed NON SEQUENTIALLY ! RAM can be accessed directly by the CPU
Windows 10 needs a minimum of 2GB of RAM just to run
computer games or image processing software you will more than likely need a
minimum of 8GB.
professional video editing and 32GB of RAM is not unusual.
These two features mean that ROM is ideal for storing key data
that must not be lost or overwritten, such as
Hardware settings that must not be changed
Initial boot up instructions for the computer
Data that should not be changed - e.g. MAC address in a
network card
Virtual memory appears to exist as main memory (RAM) but it is in fact implemented with secondary
storage devices by the operating system. Data moves automatically between main memory and
virtual memory as needed.
Non-volatile memory keeps data even if computer is switched off, whereas volatile memory loses
data when switched off
ROM (read only memory) – cannot be written to, CAN BE READ FROM
Very useful for storing instructions and data
BIOS is stored in ROM – checking that the hardware is functioning correctly and it runs the bootstrap
program to load the OS from the hard drive into RAM
RAM is random access memory:
It can be stored or accessed form any location
It holds the OS and running programs. It is easily upgraded and can be overwritten.
Secondary storage is need for:
Storage of programs and data when the power is turned off
Semi-permanent storage of data which can be changed
Backup of data file
Archive of data files
Flash memory – non-volatile memory that can be read from or written to. It is secondary storage
Bit - 1 bit
Nibble – 4 bits
Byte – 8 bits
Kilobyte – 1000 bytes
Megabyte – 1000 kilobytes
Gigabyte – 1000 megabytes
Terabyte – 1000 gigabytes
One letter – one byte
Email – 2KB
GIF – 12KB
RAW photo – 11.4 MB
Audio file (3 min) – 3MB
Uncompressed audio file – 15MB
File – 4GB
200 tiny photographs – 1.2GB
Optical – read-only, large scale distribution, small capacity
Magnetic – low cost, high capacity, cloud storage on server farms, reasonably good access
SSD – high cost, high capacity, fast access, cloud storage on server farms, very expensive, finite
number of read/write cycles, no moving parts (more reliable), more durable (no attraction to
magnetic fields)
, Drive – device that reads from or writes data from secondary storage
Media – what data is stored on
Optical – CD-R, CD-RW, DVD-R, DVD-RW, Blue _Ray
Pros: Cheap, lightweight, portable
Cons: slow access times, prone to scratches and it has the lowest data carrying capacity
Magnetic: HDDS, tapes
Pros: cheap, large capacity, quicker access times
Cons: fragile, not very reliable or durable
SDD:
Pros: Durable, fast access times, reliable, durable, low power consumption, no noise
Cons: Finite number of read/write cycles, expensive
The need and purpose of primary storage is to hold both data and programs that
are in current use by the CPU.
Primary storage devices are extremely fast and so the CPU can run at top speed.
Main memory does include Rom but it is the only type of non-volatile memory
RAM is used as main memory. It acts as a temporary store for program
instructions and data. It can only store things temporarily because it is volatile -
it must constantly be powered or it will lose any data it is holding. It can be
accessed NON SEQUENTIALLY ! RAM can be accessed directly by the CPU
Windows 10 needs a minimum of 2GB of RAM just to run
computer games or image processing software you will more than likely need a
minimum of 8GB.
professional video editing and 32GB of RAM is not unusual.
These two features mean that ROM is ideal for storing key data
that must not be lost or overwritten, such as
Hardware settings that must not be changed
Initial boot up instructions for the computer
Data that should not be changed - e.g. MAC address in a
network card
Virtual memory appears to exist as main memory (RAM) but it is in fact implemented with secondary
storage devices by the operating system. Data moves automatically between main memory and
virtual memory as needed.
