1.2 Memory Flashcards
What are the two types of memory?
- Main memory
* Secondary storage
Which memory can be directly accessed by the CPU?
Main memory
True or False? Main memory can only hold one program at a time
False - it can hold more than one making it quicker for the CPU to swap between tasks.
What is secondary storage used for?
Secondary storage is used for holding large amounts of data and programs long-term, but can only be accessed relatively slowly.
What is volatile memory?
Volatile memory is memory that loses its data once power to the memory chip is switched off or interrupted.
What is RAM used for?
- RAM is used as main memory
* It is used as a temporary store for program instructions and data
What will happen if RAM loses its power?
It will lose any data its holding because it is. volatile
Why is it called ‘Random Access Memory’?
Data or instructions can be accessed in any order (non sequentially)
What are the two types of RAM?
- DRAM (Dynamic)
* SRAM (Static)
What type of RAM is found in a RAM module and why?
- DRAM
* It is relatively inexspenive
What type of RAM is used for the cache and why?
- SRAM
* It is much faster to access than DRAM
Which type of RAM requires a refresh signal to keep its data intact?
DRAM
How much RAM does a budget laptop include?
Around 4GB
Use of which application could require up to 32GB of RAM?
A professional video editing application.
What does ROM stand for?
Read Only Memory
What are the two differences between RAM and ROM?
- ROM is read only (cannot be changed) whereas RAM is read/write memory (contents can be altered).
- ROM is non volatile (meaning it keeps its data when there is no power supply) whereas RAM is volatile.
What is ROM used to hold?
- Basic computer hardware settings
* In the past it held the BIOS to boot up the computer
Why are ROM chips not removable?
They are soldered into the motherboard.
What makes RAM chips easy to remove and update?
They are located in removable memory modules that are slotted into sockets on the motherboard.
What is the typical memory of ROM?
A few megabytes
On what type of memory is BIOS now stored and why?
Flash memory so that changes to the instructions can be made (flash memory is non volatile and read/write)
What happens when RAM gets too full?
The computer operating system can help out by temporarily marking sections of secondary storage for the CPU to store data on.
These sections are called virtual memory.
Does the CPU directly access data held in virtual memory?
- No - it asks the operating system to first load it into RAM, which is quick to access.
- Less-used data is moved from RAM to virtual memory to make room for it.
What is Disk Thrashing? (3)
- As main memory fills up, then more and more pages need to be swapped in and out of virtual memory.
- This swapping leads to a very high rate of hard disk access
- Leading to wear and tear on the disk and a slow-down in overall performance.
