All things in all posts will help you visualize about the way that computers work generally. Note that it is not the real structure of modern computers, but the way that modern computers work is nearly the same as in my posts. I am sure that if you understand about the way that computers work in my posts, you will easy to learn about all fields of computer afterward. Thank you !!!
As you know, bits are the only things in computers. Two possible states of bits are “on” and “off”. Bits help computers represent information such as pictures, emails,...So to display information immediately, computers must save all bits of information. To save information, computers need memory units.
The diagram below will display a picture about one bit of computer memory. This bit is constructed from NAND gates. We will find the way that memory bit works. Once you understand the way that it works, we will use a symbol to represent it and we will use it as components that construct “bigger” parts of computers. These “bigger” parts will be computer memory that helps save information.
Look at the diagram below to see a memory bit which is built from 4 NAND gates:
In the diagram above, we have two input signals and one output signal. “i” is the input of the bit that we want to save, “o” is the output of the bit that we saved, “s” is the input signal that decides when “i” input signal will be saved on the computer. Besides, we have three wire connections with corresponding letters “a”, “b” and “c”. I will explain the way this diagram works.
First, we start with “s” “on” and “i” “off”. “i” “off” so “a” “on”, “a” “on” and “s” “on” so “b” “off”, “b” “off” so “c” “on”, “a” “on” and “c” “on” so “o” “off”, “c” “off” and “b” “off” so “c” continue “on”. As you can see, “o” will be “off” when “s” “on” and “i” “off”. In other words, when the bit that needs to be saved is allowed (“s” “on”), that bit (“i” “off”) will be saved in memory bit (“o” “off”).
Second, we continue with “s” “on” and “i” “on”. “s” “on” and “i” “on” so “a” “off”, “a” “off” so “b” “on” and “o” “on”, “b” “on” and “o” “on” so “c” “off”, “c” “off” and “a” “off” so “o” continue “on”. As you can see, “o” will be “on” when “s” “on” and “i” “on”. In other words, when the bit that needs to be saved is allowed (“s” “on”), that bit (“i” “on”) will be saved in memory bit (“o” “on”).
In conclusion, when the bit that needs to be saved is allowed (“s” “on”), the state of the bit that needs to be saved (“i” “on” or “off”) will be saved in the memory bit (“o” “on” or “off”).
Third, we continue with “s” “off” and “i” “off”. Because before “s” “off” (“s” “on”), “i” is the same as “o”, so this case will be “s” “off”, “i” “off” and “o” “off”. “s” “off” so “a” “on” and “b” “on”, “o” “off” and “b” “on” so “c” “on”, “c” “on” and “a” “on” so “o” continue “off”. You can see that “i” input (when “s” “off”) does not affect the result in “o” output. So when “i” changes to “on” now, it can not change the state of “o”. In other words, when the bit that needs to be saved is not allowed (“s” “off”), that bit (“i” “on”) will not be saved in memory (“o” “off”).
Fourth, we continue with “s” “off” and “i” “on”. Because before “s” “off” (“s” “on”), “i” is the same as “o”, so this case will be “s” “off”, “i” “on” and “o” “on”. “s” “off” so “a” “on” and “b” “on”, “b” “on” and “o” “on” so “c” “off”, “c” “off” and “a” “on” so “o” continue “on”. You can see that “i” input (when “s” “off”) does not affect the result in “o” output. So when “i” changes to “off” now, it can not change the state of “o”. In other words, when the bit that needs to be saved is not allowed (“s” “off”), that bit (“i” “off”) will not be saved in memory (“o” “on”).
In conclusion, when the bit that needs to be saved is not allowed (“s” “off”), the state of the bit that needs to be saved (“i” “on” or “off”) will not be saved in the memory bit (“o” “off” or “on”).
From now on, you understand the way that the memory bit works. So, we do not need to repeat it again in my next posts. We will use the diagram below to represent it everytime. These are building blocks that need to build a more complex structure than this memory bit.
In the diagram, “i” is the input bit that we want to save. “s” is the input bit that allows “i” to be saved when “on” and lock memory bit when “off”. “o” is the output bit that is saved from “i” when “s” “on”. “M” is short for “Memory”. All of them are easy to remember. Thanks for reading and see you later.
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