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What is RAM? Nick Sims.

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1 What is RAM? Nick Sims

2 What is RAM? Similar to a microprocessor, a memory chip is an integrated circuit (IC) made of millions of transistors and capacitors. An integrated circuit is set of electronic circuits on one small plate ("chip") of semiconductor material, normally silicon

3 What is RAM? To create one byte, you need 8 capacitors. To create 1Mb of memory, you need... 8,388,608 capacitors. If you have a computer with 4Mb of RAM, just for the RAM you have over 33.5 million capacitors In the most common form of computer memory, dynamic random access memory (DRAM), which has a pairing of transistor and a capacitor (an electric field that changes with a simple electric pulse) to make a memory cell, which represents a single bit of data.

4 What is RAM? ­Your computer may use both static RAM and dynamic RAM at the same time, but it uses them for different reasons. Dynamic RAM is the most common type of memory in use today. Inside a dynamic RAM chip, each memory cell holds one bit of information and is made up of the two parts: a transistor and a capacitor. Transistors and capacitors are very small: so that millions of them can fit on a single memory chip. The capacitor is like a bucket holding the bit of information - a 0 or a 1 (see later slide) The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.

5 Inside the capacitor you have two plates that do not touch each others
Inside the capacitor you have two plates that do not touch each others. In other words, no electricity goes straight from one side to the other. Instead it uses magnetism. That explains why magnets and computers are not friends What is RAM? The transistor acts as a switch that lets the control circuitry on the memory chip read the capacitor or change its state.

6 What is RAM? ­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 (is a digital circuit which manages the flow of data going to and from the main memory) 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

7 What is RAM? In modern computers, the RAM works... serially! Yes. This means data is transmitted one bit at a time!! For over 20 years we used parallel devices to transfer the many memory bits between the RAM and the CPU. The fact is that properly synchronizing the electric signals of even an 8bit parallel connector actually takes more time than sending the same amount of bits serially! This is why Hard Drives now use much smaller cables and are called SATA drives.

8 Task 1. Produce a series of slides that describes what RAM is and what is the purpose of RAM 2. Find out what is the difference between Static RAM and Dynamic RAM (add it to your slides)


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