What is RAM memory

Definition of RAM Memory

RAM memory is a type of memory that allows to store and/or extract information (Read/Write), accessing randomly; that is, it can access any point or address of the same and at any time (not sequential).

RAM memory is made up of one or more chips and is used as working memory to save or delete our programs and data. It is a type of temporary memory that loses its data when the computer loses power. 

What does RAM mean?

RAM is the acronym for random access memory or random access  memory .

What is RAM used for?

The main function of RAM memory is to store data or files frequently used by the user, in order to access them quickly.

Types of RAM

There are two basic types of RAM:

  1. Dynamic RAM (DRAM)
  2. Static RAM (SRAM)

The two types of RAM differ in the technology they use to store data, with dynamic RAM being the most common.

Dynamic RAM needs to be updated thousands of times per second, while static RAM does not need to be updated, so it is faster, but also more expensive. Both types of RAM memory are volatile, that is, they lose their contents when the computer is turned off.

VRAM 

Acronym for Video RAM, a special purpose memory used by video adapters. Unlike conventional RAM memory, VRAM can be accessed by two different devices simultaneously. This allows a monitor to access VRAM for screen updates at the same time a graphics processor supplies new data. VRAM allows for better graphics performance although it is more expensive than normal RAM.

SIMM
Acronym for Single In line Memory Module, a type of package consisting of a small printed circuit board that stores memory chips, and is inserted into a SIMM socket on the motherboard or memory board. SIMMs are easier to install than the old individual memory chips, and unlike them they are measured in bytes instead of bits.

There are two types of 30 and 72 pins. The 30s come in 256K and 1Mb capacities and are hardly used anymore. The 72 come in 4, 8, 16, 32 versions. Their main disadvantage: they work in pairs.

DIMM
Acronym for Dual In line Memory Module, a type of package, consisting of a small printed circuit board that stores memory chips, which is inserted into a DIMM socket on the motherboard and generally uses a 168-pin connector. DIMM and SIMM cannot be mixed.

DIP
Acronym for Dual In line Package, a type of package consisting of storing a memory chip in a rectangular box with two rows of connection pins on each side.

RAM Disk
Refers to RAM that has been configured to simulate a hard drive. Files on a RAM disk can be accessed in the same way as files on a hard disk. However, RAM disks are approximately thousands of times faster than hard disks, and are particularly useful for applications that require frequent disk access.

Since they are constituted by normal RAM. RAM disks lose their contents once the computer is turned off. To use RAM Disks, you need to copy the files from a real hard disk at the beginning of the session and copy them back to the hard disk before shutting down the machine. Note that in the event of a power failure, any data on the RAM disk will be lost. The DOS operating system allows you to convert extended memory into a RAM Disk using the VDISK command, an acronym for Virtual DISK, another name for RAM Disks.

Cache Memory or Cache RAM
A cache is a special high-speed storage system. It can be either a reserved area of ​​main memory or an independent high-speed storage device. There are two types of cache frequently used in personal computers: memory cache and disk cache. A cache memory, also sometimes called cache storage or cache RAM, is a part of high-speed static RAM (SRAM) rather than the slow and cheap dynamic RAM (DRAM) used as main memory. Cache memory is effective because programs access the same data or instructions over and over again. By saving this information in SRAM, the computer avoids accessing the slow DRAM.

When data is found in the cache, a hit is said to have occurred, a cache being judged by its hit rate. Cache systems use a technology known as smart caching in which the system can recognize certain types of frequently used data. Strategies for determining what information should be cached are one of the most interesting problems in computer science. Some cache memories are built into the architecture of microprocessors. For example, the Pentium II processor has an L2 cache of 512 Kbytes.

Disk cache works on the same principles as cache memory, but instead of using high-speed SRAM, it uses conventional main memory. The most recently accessed hard disk data (as well as adjacent sectors) is stored in a memory buffer. When the program needs to access data on the disk, the first thing it checks is the disk cache to see if the data is already there. Disk caching can dramatically improve application performance, since accessing a byte of data in RAM can be thousands of times faster than accessing a byte on the hard drive.

SRAM
Acronym for Static Random Access Memory, is a type of memory that is faster and more reliable than the more common DRAM (Dynamic RAM). The term static is derived from the fact that it needs to be refreshed fewer times than dynamic RAM.

Static RAM chips have access times on the order of 10 to 30 nanoseconds, while dynamic RAMs are above 30, and bipolar and ECL memories are below 10 nanoseconds.

A bit of static RAM is built with a — like flip-flop circuit that allows current to flow back and forth based on which of two transistors is turned on. Static RAMs do not require refresh circuitry like dynamic RAMs, but they do require more space and use more power. SRAM, due to its high speed, is used as cache memory.

DRAM
Acronym for Dynamic RAM, a type of large capacity memory that needs to be constantly refreshed (re-energized) or it would lose its content. It generally uses a transistor and a capacitor to represent a bit. Capacitors must be energized hundreds of times per second to maintain charges. Unlike firmware chips (ROMs, PROMs, etc.) the two main variations of RAM (dynamic and static) lose their contents when power is removed. Contrast with static RAM.

Dynamic RAM is sometimes mistakenly listed as a package type in memory advertisements; for example «DRAMs, SIMMs and SIPs are sold», when it should be said «DIPs, SIMMs and SIPs» the three types of typical encapsulation to store dynamic RAM chips.

Also sometimes the term RAM (Random Access Memory) is used to refer to DRAM and distinguish it from static RAM (SRAM) which is faster and more stable than dynamic RAM, but requires more power and is more expensive.

SDRAM
Acronym for Synchronous DRAM, Synchronous DRAM. This type of memory is connected to the system clock and is designed to be able to read or write at one clock cycle per access, that is, without intermediate wait states. SDRAM interleaves two or more internal memory arrays in such a way that while one array is being accessed, the next one is being prepared for access. SDRAM-II is faster SDRAM technology. Also known as DDR DRAM or DDR SDRAM (Double Data Rate DRAM or SDRAM), it allows data to be read and written at twice the bus speed.

FPM
Acronym for Fast Page Mode, memory in paged mode, the most common design of dynamic RAM chips. Access to memory bits is done by means of coordinates, row and column. Before paginated mode, it was read by clicking the row and column of the selected lines. With page mode, the row is selected only once for all columns (bits) within the row, resulting in fast access. Paged mode memory is also called Fast Page mode memory or FPM memory, FPM RAM, FPM DRAM. The term “fast” was added when newer chips started running at 100 nanoseconds and even higher.

EDO
Acronym for Extended Data Output, a type of dynamic RAM chip that improves Fast Page memory mode performance by about 10%. Being a subset of Fast Page, it can be replaced by Fast Page mode chips.

However, if the memory controller is not designed for the faster EDO chips, performance will be the same as Fast Page mode.

EDO eliminates wait states by keeping the output buffer active until the next cycle begins.

BEDO (Burst EDO) is a faster type of EDO that improves speed by using an address counter for following addresses and a ‘pipeline’ state that overlaps the operations.

PB SRAM
Acronym for Pipeline Burst SRAM. ‘Pipeline’ is a category of techniques that provide simultaneous or parallel processing within the computer, and refers to overlapping operations moving data or instructions in a conceptual ‘pipeline’ with all phases of the ‘pipeline’ processing simultaneously. For example, while one instruction is executing, the computer is decoding the next instruction. In vector processors, multiple steps of floating point operations can be processed simultaneously

The PB SRAM works in this way and moves at speeds between 4 and 8 nanoseconds.

Personal computers (PCs) use dynamic RAM. All DIMM, SIMM, or RIMM dynamic RAM chips refresh every few milliseconds by rewriting data to the module.

Static RAM (SRAM)

It is often used in cache memory and is much faster and does not require refreshing like dynamic RAM. SRAM retains information and is capable of running at higher speeds than DRAM. Most volatile memory is dynamic RAM, since it uses a single transistor and storage capacitor for each bit.

Difference Between DRAM and SRAM

The two types of RAM differ in the technology used to store information, with dynamic RAM being the most common. Dynamic RAM needs to be updated thousands of times per second, while static RAM does not need to be updated, SRAM is faster, but also more expensive. Both types of RAM memory are volatile, that is, they lose their contents when the computer is turned off. DRAM memories are cheaper than SRAM, it is common to see PC manufacturers use DRAM.

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