Can anyone give me a rough idea how memory works in a computer?

Question

RAM specifically

Answer 1

Random access memory (RAM) is the best known form of computer memory. 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.

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. The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.

A capacitor is like a small bucket that is able to store electrons. To store a 1 in the memory cell, the bucket is filled with electrons. To store a 0, it is emptied. The problem with the capacitor's bucket is that it has a leak. In a matter of a few milliseconds a full bucket becomes empty. Therefore, for dynamic memory to work, either the CPU or the memory controller has to come along and recharge all of the capacitors holding a 1 before they discharge. To do this, the memory controller reads the memory and then writes it right back. This refresh operation happens automatically thousands of times per second.

This refresh operation is where dynamic RAM gets its name. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. The downside of all of this refreshing is that it takes time and slows down the memory.

Memory cells are etched onto a silicon wafer in an array of columns (bitlines) and rows (wordlines). The intersection of a bitline and wordline constitutes the address of the memory cell.

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.

Answer 2

Computer information is stored on hard drive, which is basically a spinning metal disc (like a CD, just more complex). Because it's mechanical, retrieval of this information is relatively slow. That's why the CPU (brain of a computer) prefers to request information not from the hard drive, but from a special electronic chip called RAM (memory), which is thousands times faster.

There's a special instruction chip which requests data from the hard drive and puts it in memory. This idea of retrieving information for future use is called "caching" and is very common in computing. It's purpose is to speed up data transfer by "guessing" what the CPU is gonna need next.

Theoretically, all information could be stored in a chip, instead of a hard drive, but those chips are far more expensive. A typical personal computer can have 200 gigabytes of hard drive storage, but only 1 gigabyte of memory.

Answer 3

only when its plugged in, as i found out the hard way once.

RAM has about a billion switches inside set to 0 or 1, all theese 0's and 1's eventually make up computer information.. its called RANDOM acces memory because you can access any point of it at any time (unlike say data tapes where you have to play form the beginning)

its used as "thinking memory" ie where little bits of info can be stored so your computer can work out other things elsewhere.. its the silicon equivalent of a notepad and pen.

you make the actual working out in your head (CPU) and then tell someone the answer (graphics and sound)

if you want to know exactly how each ram module works, you should talk to frank.

Answer 4

Memory is held in a bit, called a bistable circuit
GCSE Physics, circuits, is the start of understanding it XD

Answer 5

You really need to read up a bit to understand properly.

This will get you started: http://en.wikipedia.org/wiki/RAM

Answer 6

Go on this website.