OCR GCSE (9-1) COMPUTER SCIENCE 1.2 MEMORY TEST QUESTIONS AND ANSWERS

What is RAM? Random Access Memory What is ROM? Read Only Memory What does volatile mean? Loses all contents when power is lost Is RAM volatile or non-volatile? RAM is volatile Is ROM volatile or non-volatile? ROM is non-volatile What is the purpose of RAM? To store files/data and the part of the operating system currently in use, to be accessed by the CPU What is the purpose of ROM? Contains the BIOS and bootstrap loader for starting the computer - the most basic operating instructions for the computer What is the purpose of the bootstrap loader? Contains instructions for starting the computer What is the purpose of the BIOS? A type of firmware which contains all the instructions a computer needs to boot up properly - tells the CPU to perform self checks and set up the computer, e.g. test the memory is working okay, see what hardware is present and copy the OS into the RAM What is firmware? Hardware specific software built into a device which gives basic instructions to a computer What is more likely to be the capacity of the RAM - gigabytes or megabytes? Gigabytes What is more likely to be the capacity of the ROM - gigabytes or megabytes? Megabytes Which can be written to - RAM or ROM? RAM What are the two types of RAM? DRAM (dynamic) and SRAM (static) What is DRAM? Dynamic RAM, the most common form of memory that must be refreshed with capacitors occasionally, used for main memory What is SRAM? Static RAM, a lower-power and faster but more expensive type of memory, used for CPU caches Is RAM a form of main memory? Yes How much RAM does a smartphone need? 2GB How much RAM does a gaming console need? 4GB How much RAM does a laptop need? 8GB How much RAM does a computer need? 16GB or more What defines how much RAM something needs? A computer needs at least enough RAM to run the operating system Why is RAM used instead of secondary storage? It is much faster to access, and has a much faster read/write speed (as it is much closer to the CPU) How could the addition of extra RAM speed up a computer? Why might this not always be effective? If a computer has too little RAM, it might run slowly due to the use of virtual memory. The more RAM, the more applications or more memory intensive applications it can smoothly run, making it faster overall. It's easy to upgrade RAM on a PC or laptop - it's just a matter of replacing the sticks to higher-capacity (or higher speed) ones. If the computer already has plenty of RAM to run everything the user wants, increasing the RAM may make no difference to performance. Additionally, if the processor is slow, this is an entirely different issue. What is virtual memory? A technique that converts a part of secondary storage temporarily to an extension of the RAM for application data when the RAM is full When might virtual memory be needed? When running too many applications When running a particularly memory intensive program What happens when data in virtual memory is needed by the CPU? It must be swapped out of the secondary storage into the RAM What are the disadvantages of virtual memory? -Makes the computer slow to respond as data transfer to secondary storage is slower than to RAM (read/write speed) -Programs are being paged (swapped) constantly in and out of RAM, leading to disk thrashing, where the CPU spends more time swapping data than actually executing the program What is an example of flash memory? The BIOS - retains settings after power off What is flash memory? Non-volatile secondary storage which can be updated by being 'flashed' with UV light. Used by the BIOS to retain settings after power off, and used as permanent storage by portable devices What is the advantage and disadvantage of flash memory? More reliable than magnetic storage as there are no moving parts More expensive than magnetic storage and therefore a smaller capacity Can flash memory ever be written to? Yes - It depends on where it is used What is used in flash memory to store one bit of data? A transistor Where is flash memory used? SSDs (solid-state drives), USB sticks, SD cards