The key difference between these newer pin types and the original DIP configuration is that SOJ and TSOP chips are surface-mounted to the PCB. Most of these chips use a small outline J-lead (SOJ) pin configuration, but quite a few manufacturers use the thin small outline package (TSOP) configuration as well. The solution was to place the memory chips, along with all of the support components, on a separate printed circuit board (PCB) that could then be plugged into a special connector ( memory bank) on the motherboard. This method worked fine when computers typically operated on a couple of megabytes or less of RAM, but as the need for memory grew, the number of chips needing space on the motherboard increased. This pin configuration could be soldered into holes on the computer's motherboard or plugged into a socket that was soldered on the motherboard. Memory chips in desktop computers originally used a pin configuration called dual inline package (DIP). These circuits perform functions such as: So, the memory cells have a whole support infrastructure of other specialized circuits. Memory cells alone would be worthless without some way to get information in and out of them. A memory chip rating of 70ns means that it takes 70 nanoseconds to completely read and recharge each cell. The length of time necessary to do all this is so short that it is expressed in nanoseconds (billionths of a second). The counter tracks the refresh sequence based on which rows have been accessed in what order. If it is more than 50 percent, it reads it as a 1 otherwise it reads it as a 0. When reading, the sense-amplifier determines the level of charge in the capacitor. When writing, the row lines contain the state the capacitor should take on. The intersection of a bitline and wordline constitutes the address of the memory cell.ĭRAM works by sending a charge through the appropriate column (CAS) to activate the transistor at each bit in the column. Memory cells are etched onto a silicon wafer in an array of columns ( bitlines) and rows ( wordlines). In this article, you'll learn all about what RAM is, what kind you should buy and how to install it. The downside of all this refreshing is that it takes time and slows down the memory. Dynamic RAM has to be dynamically refreshed all of the time or it forgets what it is holding. This refresh operation is where dynamic RAM gets its name. It needs to be refreshed periodically or it will discharge to 0. The capacitor in a dynamic RAM memory cell is like a leaky bucket. This refresh operation happens automatically thousands of times per second. To do this, the memory controller reads the memory and then writes it right back. 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. In a matter of a few milliseconds a full bucket becomes empty. The problem with the capacitor's bucket is that it has a leak. To store a 1 in the memory cell, the bucket is filled with electrons. The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.Ī capacitor is like a small bucket that can store electrons. The capacitor holds the bit of information - a 0 or a 1 (see How Bits and Bytes Work for information on bits). 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. Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. RAM is basically your computer's short-term memory.
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