What Is Cache Memory?
Cache Memory is a very high-speed memory, but it has limited kilobytes. It is used to speed up and synchronize with high-speed Central Process Unit (CPU).
It is more expensive than the Random Acces Memory (RAM) or disk memory. Cache memory is a high-speed memory type that functions as a buffer between the RAM and the CPU. It includes frequently demanded data and instructions so that they are instantly accessible to the CPU if required.
It is used to decrease the average time to locate data from the Main memory. The cache memory is a smaller and faster memory which collects copies of the data from commonly used main memory locations. There are various independent caches in a CPU, which receive instructions, including data.
In many of the cases, cache memory is called as CPU memory since it is integrated within the CPU chip that is separated by BUS interconnect wit the CPU, which help the processor to be accessible quickly and able to increase efficiency.
Type of Cache memory
It increase the speed of the CPU, but it is expensive. An example of Cache Memory is divided into the various levels that is L1, L2, L3.
Level 1 (L1) cache or Primary Cache
It is the primary type of cache memory. The size of the L1 cache insignificant compared to others that are between 2KB (KiloBytes) to 64KB (KiloBytes); it depends on the computer processor. It is an installed register in the computer microprocessor(CPU).
The Instructions that are needed by the CPU that is firstly searching in L1 Cache. Examples of registers are accumulator, Program counter, an address register, etc.
Level 2 (L2) cache or Secondary Cache
It is a secondary type of cache memory. The capacity of the L2 cache is more spacious than L1 that is between 256KB (KiloBytes) to 512KB(KiloBytes).L2 cache are Located on a computer microprocessor.
After examining the Instructions in L1 Cache, if not observed, then it explored into L2 cache by computer microprocessor. The high-speed system Bus was interconnecting the cache to the microprocessor.
Level 3 (L3) cache or Main Memory
The L3 cache is more extensive but also slower than L1 and L2; its size is between 1MB (MegaBytes) to 8MB(MegaBytes).In Multicore processors, each core has separate L1 and L2, but all core share a shared L3 cache. L3 cache twice speeds than the RAM.
Importance of Cache memory
The Cache memory function in the path within the processor and the memory. The cache memory has minor access time than memory and is faster than the main memory. Cache memory has an access time of (100 nanoseconds) 100ns, while the main memory may hold an access time of (700 nanoseconds) 700ns.
The cache memory is costly and hence is limited in capacity. In staring days the cache memory is available separately, but now it comes with integrated along with the microprocessors with a chip that contains cache memory. The need for the cache memory arrives, due to mismatch between the speed of the primary memory and CPU.
The clock of The CPU is faster, whereas the primary memory access time is slower. Therefore, it does not matter how fast your processor is, and the processing speed depends more on the speed of the main memory. Because of this reason, a cache memory having access time closer to the processor speed is developed.
The cache memory stores the program currently being executed or which may be executed within a short period. The cache memory stores temporary data that the CPU usually need for manipulation.
Cache memory works according to various algorithms that we’ll see in further part soon, which determine what data it has to store. These algorithms work out the possibility of deciding which data would be most commonly required. This possibility is worked out based on prior observations. The cache memory is costly and hence is limited in capacity.
Cache Memory VS RAM
- Read/Write the rate of cache memory is faster than RAM.
- Cache Memory is more valuable than RAM.
- Cache Memory is used to save irrelevant data.
- CPU reads Cache Memory before accommodating RAM.
- Read or Write speed of RAM is slower than Cache Memory.
- RAM is defined as expensive than Cache Memory.
- RAM is used to store less irrelevant data.
- CPU reads RAM after expressing Cache Memory.
What is RAM?
RAM (Random Access Memory); it is likewise referred to as a computer’s memory. It is a memory like when power is off the data will be erased.
There are two types of RAM.
SRAM (Static random-access memory) uses the data to store a single bit of information. It does not have to be refreshed.
DRAM (Dynamic random-access memory) stores each bit of data on a separate capacitor. This is a useful way to store data in memory because it needs limited physical space to store the equivalent amount of data than if it was saved statically.
How Cache Memory Works
It checks for an identical entry from the cache when the processor requires to read or write a location in memory.
If the processor determines that the memory location is in the cache, a cache hit occurred, and the information is read or write from cache memory.
If the processor doesn’t find the memory location in the cache memory, a cache miss has occurred. For a cache miss, the cache allows copies and a new record in data from memory. The cache’s contents perform the request.