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capacity of secondary storage of computer systems. Thus a computer having 32 MB of
memory is capable of storing 32 x 1048576 = 33,554,432 bytes or characters.
Sometimes the memory capacity of a computer system is also stated in terms of number
of words. However, if the memory capacity is stated in terms of words, it is necessary to
know the word size in bits or bytes in order to determine the actual memory capacity of
the computer. Thus, while specifying the memory capacity in terms of words, it is
customary to specify the total number of bits per word along with the total number of
words. So a memory with 4096 locations each with a different address and with each
location storing 16 bits is called a "16-bit 4096-word memory, or, in the vernacular of the
computer trade, a "4 K 16-bit memory". Similarly, a memory having 2 15 words with each
word of 16 bits is called a "32 K 16-bit memory". If the word size of a memory is 8 bits
(equal to a byte) then it becomes immaterial whether the memory capacity is expressed in
terms of bytes or words. Thus a memory having 2 16 words with each word of 8 bits is
simply referred to as 64 K memory (word size of 8-bits is implicit here).
Static and Dynamic RAM
When people talk about computer memory, they usually mean the volatile RAM memory.
Physically, this memory consists of some integrated circuit chips (IC chips shown in
Figure 1.2) either on the motherboard or on a small circuit board attached to the
motherboard. A computer's motherboard is designed so that its memory capacity can be
easily enhanced by adding more memory chips. Hence, if you decide to have more
memory than your computer currently has, you can buy more memory chips, open up
your computer, and plug it in the empty memory slots on the motherboard. This job is
normally done by the service engineers. The additional RAM chips, which plug into'special sockets on the motherboard are also known as single in-line memory modules
RAM chips are of two types - dynamic and static. A dynamic RAM (DRAM), uses an
external circuitry to periodically "regenerate&qu...
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This document was uploaded on 04/07/2014.
- Spring '14