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Size of memory
Memory chips are available in a variety of sizes.
The size of a memory chip is described as MxN,
- where M is the number of addressable words and
- N is the number of bits per word.
- For example:
- A 32Kx8 memory chip has 32K addresses, each containing 8 bits.
- A 64Mx1 memory chip has 64 Meg (226) of addresses,each containing a single bit.
Memory chips are available in many different sizes. A memory chip is referred to as being MxN. Such a chip contains M is the number of addressable storage locations with N bits per location (address). A memory chip may contain anywhere from hundreds to millions of addresses. Each memory address may contain from one to hundreds of bits. Usually the width (the number of bits per address) is a power of 2 between 1 and 16. As an example, a16Mx1 chip contains16 Meg (16x220) of addresses with each address containing a single bit. A 2kx4 chip has 2 K (2x210) of addresses, each of which contains 4 bits.
The rule of thumb for memory chip selection is to use the smallest number of chips sufficient for the application, and make the memory components expandable in the future. More memory chips mean more complex printed circuit boards and more assembly work. These factors increase the final cost of the memory component.