Topic 2: Memory and Storage Flashcards
What is primary memory
Primary memory is built inside the computer. As a result, data can be read from and written to primary memory extremely quickly. This gives the processor fast access to the data and instructions that the primary memory holds. This usually consists of RAM and ROM
What are the characteristics of ROM
Read only memory (ROM) is non-volatile primary memory. Its contents are not lost when the computer is turned off. ROM can be read from, but not written to.
What are the characteristics of RAM
Random access memory (RAM) is volatile primary memory. Once the computer is switched off, the data and instructions held in RAM are lost. RAM is used to hold data and instructions that are currently in use.
Why may virtual memory be needed in a computer
There are times when the amount of RAM needed to hold all running programs and data is greater than the amount of RAM available to the computer. When this happens, part of the computer’s secondary storage, such as the hard disk, can be used to store data temporarily.
How does virtual memory work
Virtual memory enables data that is in RAM and not currently being used to be transferred to the hard disk. This frees up room in RAM for other programs and data. When the data on the hard disk is needed again, any other unused data is transferred to the hard disk before the original data is transferred back to RAM.
Why do computers have secondary storage
Secondary storage is non-volatile, long-term storage. It is used to keep programs and data indefinitely. Without secondary storage all programs and data would be lost the moment the computer is switched off.
What are some examples of secondary data
Secondary storage devices are generally separated into three types:
-magnetic storage devices, such as hard disk drives
-optical storage devices, such as CD, DVD and Blu-ray discs
-solid state storage devices, such as solid state drives and USB memory sticks
What are the advantages / disadvantages of magnetic secondary storage
Magnetic devices are fairly cheap, high in capacity and durable. However, they are susceptible to damage if dropped. They are also vulnerable to magnetic fields. A strong magnet might possibly erase the data the device holds.
What are the advantages / disadvantages of solid state secondary storage
Solid state devices require little power, making them ideal for portable devices where battery life is a big consideration. Since this type of memory is expensive, solid state devices tend to be smaller in capacity than other types.
What are the advantages / disadvantages of optical secondary storage
Portable, can hold a lot of data but more expensive than magnetic and can lose data when scratched
