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Pseudo-static RAM often takes the place of the expensive static type in mass-produced mobile phones, various smart devices and automotive computer modules. This distinction gives a speed advantage over the dynamic chip, while still keeping production cost relatively low. This type is built similarly to dynamic RAM, but with an integrated memory controller soldered onto its circuit board. Therefore, static RAM is used to create the CPU's speed-sensitive cache, while dynamic RAM forms the larger system RAM space.Īdditionally, there exists a state between the two, called pseudo-static RAM. To sum it up: Static RAM is fast and expensive, and dynamic RAM is less expensive and slower. Static RAM also uses less power than dynamic RAM. Static chips typically only hold 1 megabyte of memory or less, while many modern DRAM sticks can hold several gigabytes of memory. Therefore you get less memory per chip, and that makes SRAM a lot more expensive. However, because it has more parts, a static memory cell takes a lot more space on a chip than a dynamic memory cell. This makes SRAM significantly faster than DRAM. A flip-flop for a memory cell takes four or six transistors along with some wiring, but never has to be refreshed. In SRAM, a form of flip-flop holds each bit of memory (see How Boolean Gates Work for detail on flip-flops). Static RAM uses a completely different technology. The current standard for dynamic RAM is known as DDR4, and allows for up to 64 gigabytes of memory on a single chip, as well as faster data speeds and better energy efficiency compared to previous RAM standards. The downside of all of 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 DRAM gets its name.

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.

A capacitor is like a small bucket that is able to store electrons.

What is static ram pdf