What is RAM and How Its Work.

 Ram(Random Access Memory)

Random access memory (RAM) is the best-known form of computer memory. This is what allows your computer to surf the internet and then quickly switch to loading an application or editing a document. RAM is considered "random access" because you can access any memory cell directly if you know the row and column that intersect at that cell.

One of the key characteristics of RAM is that it is much faster than a hard disk drive or other long term storage device, which means that the computer is not kept waiting for data to process.

he name random access memory derives from the fact that, in general, any random bit of data can be read from or written to random access memory as quickly as any other bit. This contrasts with storage media such as spinning disks or tape, where the access speed depends on the exact location of the data on the storage media, the speed of rotation of the media, and other factors.

How RAM Work:

RAM is basically your computer's short-term memory. Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. In the most common form of computer memory, dynamic random access memory (DRAM), a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. The capacitor holds the bit of information — a 0 or a 1 (see How Bits and Bytes Work for information on bits). The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.

• When you turn on your computer and open a spreadsheet to edit it, but first check your email, you’ll have used memory in several different ways. Memory is used to load and run applications, such as your spreadsheet program, respond to commands, such as any edits you made in the spreadsheet, or toggle between multiple programs, such as when you left the spreadsheet to check email. Memory is almost always being actively used by your computer

• DRAM works by sending a charge through the appropriate column (CAS) to activate the transistor at each bit in the column. When writing, the row lines contain the state the capacitor should take on. When reading, the sense-amplifier determines the level of charge in the capacitor. If it is more than 50 percent, it reads it as a 1; otherwise it reads it as a 0. The counter tracks the refresh sequence based on which rows have been accessed in what order. The length of time necessary to do all this is so short that it is expressed in nanoseconds (billionths of a second). A memory chip rating of 70ns means that it takes 70 nanoseconds to completely read and recharge each cell.

• Static RAM uses a completely different technology. In static RAM, a form of flip-flop holds each bit of memory (see How Boolean Logic Works for details on flip-flops). A flip-flop for a memory cell takes four or six transistors along with some wiring, but never has to be refreshed. This makes static RAM significantly faster than dynamic RAM. However, because it has more parts, a static memory cell takes up a lot more space on a chip than a dynamic memory cell. Therefore, you get less memory per chip, and that increases its price. Static RAM is fast and expensive, and dynamic RAM is less expensive and slower. So static RAM is used to create the CPU's speed-sensitive cache, while dynamic RAM forms the larger system RAM space.

• As illustrated in the graphic above, the function of RAM is to provide fast temporary storage and workspace for data and program code, which includes both applications and the system’s operating system along with hardware drivers for each hardware device, such as hard disk controllers, keyboards and printers. But because random access memory works very quickly compared to longer term storage, it is also used in other ways which take advantage of this speed. One example is the use of random access memory as a “RAM disk.” 

• This reserves random access memory space and uses it as a virtual hard disk drive. This is assigned a drive letter, and appears exactly like a conventional disk drive except that it works much faster. In some circumstances this can be very useful, but the drawbacks are that the size of a RAM disk is limited, and using a RAM disk means there is less random access memory left for regular usage. 

• Another use for random access memory is “shadow RAM.” In some operating systems (but not Windows), some of the contents of the system’s BIOS  – which is stored in the system’s read-only memory (ROM) – is copied into RAM. The system then uses this copy of the BIOS code instead of the original version stored in ROM. The benefit of this is speed: reading BIOS code from RAM is about twice as fast as reading it from ROM