Memory, Cache, Definition and Purpose of Flash!

First, the subject is different.

1. Cache: refers to the access speed is faster than the general random access memory.

RAM) is a type of high-speed memory.

2. Memory: It is one of the important components in the computer, it is external memory.

A bridge to communicate with the CPU.

3. Flash memory: an electronic type.

Programmatic read-only memory can be purged.

forms of memory that allow to be wiped or written multiple times during operation.

Second, the characteristics are different.

1. Cache: It does not use DRAM technology like the main memory of the system, but uses the expensive but faster SRAM technology.

2. Memory: The operation of memory also determines the stable operation of the computer. Memory sticks.

is made up of memory chips.

Circuit boards, gold fingers.

and other parts.

3. Flash memory: It is a special EPROM written in macro blocks. A single erase of the flash memory erases the entire chip.

Third, the role is different.

1. Cache: A memory that can exchange data for high-speed data, which exchanges data with the CPU before memory, so the source training rate is very fast.

2. Memory: It is used to temporarily store the computing data in the CPU, as well as external memory such as hard disk.

Data exchanged.

3. Flash memory: It is a non-volatile memory.

Even if the power is off, the data will not be lost. Because flash memory does not rewrite data on a per-literal basis like RAM (Random Access Memory), it cannot replace RAM.

Categories: Computer Networking.

Analysis: The hard disk is where the data and programs are stored, and all the software of the computer is stored in it, just like a warehouse. The data here can be stored forever and will not disappear when the power is lost.

When the computer needs to run the program, because the processor cannot read the data directly from the hard disk, it will first read the program and data from the hard disk to the memory, and the memory is also memory, but the data inside will disappear when the power is off, and the CPU will read the instructions from the memory to execute. The read and write speed of memory is tens to hundreds of times that of hard disk.

When the CPU reads the instruction execution, although the memory has increased the speed of data reading from the very slow of the hard disk to very fast, but it will still not be able to keep up with the speed of the CPU, so the cache is designed to buffer the instructions, the cache is an ultra-high-speed memory between the CPU and the memory, the read and write speed is extremely fast and the speed is extremely fast Sakura, but due to the high cost, it is not very large, when reading the instructions, the CPU will first query whether there is the same instruction in the cache, if there is, read directly from the cache, There is no reading from coarse memory and writing instructions to the cache in preparation for the next query, and at the same time updating and erasing instructions in the cache that have not been read for a long time. Caches can have 1 layer or more than 2 layers, which is the so-called Level 1 cache and Level 2 cache. So the whole order is cpu - > cache - > memory - > hard disk.

Cache refers to the memory that can exchange data at high speeds, and it exchanges data with the CPU before memory, so the rate is fast. L1 cache is the first layer of the CPU's cache.

The capacity and structure of the built-in L1 cache have a greater impact on the performance of the CPU, but the cache memory.

All of them are composed of static RAM, the structure is complex, and the capacity of L1 cache cannot be too large when the CPU die area is not too large. Generally, the capacity of L1 cache is usually 32— Cache (L2 cache) is the second layer of CPU cache, which is divided into internal and external chips. The internal L2 cache runs at the same rate as the main frequency, while the external L2 cache is only half the main frequency.

The L2 cache capacity of the CPU will also affect the performance of the CPU, the principle is that the bigger the better, the L2 cache of the average desktop CPU is generally 128KB to 2MB or higher, and the L2 cache of the CPU on laptops, servers and workstations can reach up to 1MB-3MB.

The cache is only a copy of a small part of the data in memory, so when the CPU goes to the cache to find the data, it will also be unable to find it (because the data is not copied from the memory to the cache), then the CPU will still go to the memory to find the data, so that the speed of the system will slow down, but the CPU will copy the data to the cache, so that the next time not to retrieve it in memory. With the change of time, the most frequently accessed data is not static, that is to say, the data that is not frequent just now needs to be frequently accessed at this time, and the data that is still the most frequent just now is not frequent, so the data in the cache should be replaced frequently according to a certain algorithm, so as to ensure that the data in the cache is the most frequently accessed.

Generally speaking, the cache is integrated into the CPU.

If the cache is much faster than the memory in terms of the speed of accessing data, the operating system of our computer will allocate memory for the application, but due to the low efficiency of memory access (relative to the processing speed of the CPU), the cache is to solve the access of the high-speed CPU to the slow memory.

There is also the concept of L1 caching and L2 caching.

Before that, let's talk about RAM (temporary, dynamic storage data, specifically what we usually call memory sticks) and ROM (permanent, fixed storage data, in layman's terms, we are talking about discs, ***, mobile phone memory cards, etc.).

The RAM is power-off, which means that all the data stored in the RAM is cleared after the device is shut down, and the data in the ROM still exists.

There are two types of RAM, static and dynamic, and static RAM is faster than dynamic RAM.

Static RAM has a relatively low level of integration, and stores the same data, and static RAM consumes about six times more volume than dynamic RAM.

For the same capacity, static RAM is four times more than dynamic RAM.

We need to know that caching as static RAM is more expensive, so don't fantasize about increasing the cache or anything.

But we have a compromise solution, which is to increase the high-speed dynamic RAM as a cache, which is faster than the regular dynamic RAM, of course, there is still a certain gap between the speed and the static RAM (no way, it's all money (O)).

RAM is stored in the data and instructions that are frequently used by the device, they are copied from memory, which is maintained by a set of algorithms, at the same time, the things stored in RAM are not fixed, and will change with the change of time and usage habits, in a word, the data kept internally are determined by the algorithm. When the CPU is working, it first goes to find static RAM (L1 cache), then to find high-speed dynamic RAM (L2 cache) that is added later, and finally memory.

Memory is internal storage and refers to the place where software is installed. The larger the memory, the more software you can install. Cache means that when running software, it must be extracted first and released in the cache. It's a temporary transition. So the bigger the cache, the faster it runs.

CPU cache memory is a temporary memory between the CPU and memory, which is smaller than memory but swaps faster. The data in the cache is a small part of the memory, but this small part is about to be accessed by the CPU in a short period of time, and when the CPU calls a large amount of data, it can be called directly from the cache without memory, thus speeding up the read speed. It can be seen that adding a cache to the CPU is an efficient solution, so that the entire internal memory (cache + memory) becomes a high-speed storage system with both cache and large capacity of memory.

Caching has a significant impact on CPU performance, mainly due to the order in which the CPU exchanges data and the bandwidth between the CPU and the cache.

1 The difference between memory and cache: memory is a highway, and cache is a temporary parking place, 2 The connection between memory and cache: due to temporary congestion on the highway, other later or other arrangements will go to the temporary parking place for a while.

That's the difference between memory and cache.

Memory is internal memory and is a hardware device; Caching is a relatively large concept that is used to pre-read information (such as the cache of a hard disk), or to temporarily store some information that is not long-lasting.

The data in the cache is a small part of the memory, but this small part is about to be accessed by the CPU in a short period of time, and when the CPU calls a large amount of data, it can be called directly from the cache without memory, thus speeding up the read.

.Because the cache is only a copy of a small part of the data in memory, when the CPU goes to the cache to find data, it will also be unable to find it (because the data is not copied from the memory to the cache), then the CPU will still go to the memory to find the data, so that the speed of the system will slow down, but the CPU will copy the data to the cache, so that the next time do not go back to the memory.

2.Because with the change of time, the most frequently accessed data is not static, that is to say, the data that was not frequent just now already needs to be frequently accessed at this time, and the data that was the most frequent just now is not frequent again, so the data in the cache should be frequently replaced according to a certain algorithm, so as to ensure that the data in the cache is the most frequently accessed.

The difference is very simple, memory is storage, cache is buffer area, and contact is where things are stored.

Memory is a component of a computer, and the cache is stored in the CPU and hard disk. The CPU is the brain, the memory is the channel, and the hard disk is the big warehouse storage. A good CPU is the headquarters, the hard disk is the military warehouse, the cache is the equipment supporting facilities in the two, and the memory is the channel to communicate between the headquarters and the military warehouse!

That's probably it!

To put it simply, memory is the amount of space to be stored, and cache is an indicator of how fast or slow it runs!

Two brothers are indispensable. Both are storage documents. One is outside. One in it. Work at the same time.