1.2 - Memory

• Random Access Memory is a volatile type of memory where it stores currently running programs and Data.
• Read-Only memory is a type of memory that is only read and not written to.
• Volatile means data and instructions are temporary so when power is switched off all the data and instructions are deleted.
• Non-volatile means data and instructions are temporary so when power is switched off all the data and instructions are deleted.
• The operating system is the software that manages the computer and controls the programs that run on it.
• Virtual memory is part of the hard drive used as an extension to RAM.
• The advantages of virtual memory is that it is cheap and prevents error messages.
• The disadvantages of virtual memory is that accessing virtual memory is very slow and to access the data, the existing data in the RAM needs to be copied to the virtual memory then data in virtual memory needs to be copied to the RAM.
• The BIOS controls the basic technical configuration of the computer such as the processor speed and system time.
• The RAM's size is typically 4GB - 32GB whereas the ROM's size is typically 4MB - 8MB.
• RAM stores running programs and the operating system whereas the ROM stores the BIOS and bootstrap.
• The RAM is volatile and can both read and write data whereas ROM is not volatile and can only read not write.
• Increasing RAM would lead to more instructions can be executed at the same time, more memory space, opens software faster, reduces use of VM, runs more memory intensive programs.
• Primary storage is the memory that is directly accessible by the CPU and is used to store data and instructions.
• Secondary storage is a type of storage that is used to store data and programs that are currently being used by the computer.
• An example of secondary storage is HDD and SSD. An offline secondary storage is flash memory and SD cards.
• Magnetic storage is mechanical parts moving over the disks surface to read and write data magnetically.
• Optical are lasers which read and write data using light.
• Solid state is data recorded onto solid memory chips without any moving parts.
• A magnetic disk has concentric circles called tracks and they are each divided into sectors. The disk heads mounted on mechanical arms reads and writes the data.
• The advantages of magnetic storage is that it is cheap, has large storage capacities and has a relatively fast write speed.
• The disadvantages of magnetic storage is that it has lots of mechanical parts, not robust and not portable.
• Magnetic storage is used in personal computers and storage of large quantities of data. The capacity is around 500GB - 12TB.
• Optical storage is stored as pits and lands burnt or pressed into a spiral track circulating outwards from the centre. Laser beams passes over the pits and lands and the level of reflection is measured.
• The advantages of optical storage is that it is cheap, portable and takes up less space physically.
• The disadvantages of optical storage is that it has less storage capacity, not robust, requires a CD reader and it has slow write speeds.
• CD-ROM have a capacity up to 720b, DVD has a capacity up to 8.4GB and a Blu-Ray has a capacity up to 50GB.
• Flash memory works by large electrical currents used to force electrons through a barrier and traps them.
• The advantages of SSDs are that it durable and robust, fast read and write speeds, fast start up times.
• The disadvantages of SSDs are that it is expensive and it is not as durable as HDDs.
• SSDs have a capacity from 100GN to 16TB.
• Flash memory have low costs, portable and durable.
• RAM is volatile whereas flash memory is non-volatile.
• RAM has a faster access and stores data than flash memory.
• RAM stores currently running data and program instructions whereas flash memory stores files and software.
• RAM can be directly accessed by CPU whereas flash memory data has to go to RAM before CPU.
• In computing power on = 1 and power off = 0.
• Binary number system consists of only 0s and 1s.
• The format used for storing is numbers, text, images, sound and program instructions.
• 1 bit is a single 0 or 1.