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| 31.1 Introduction |
| Read only memories are used to store constants, control information and program instructions in digital systems. They may also be thought of as components that provide a fixed, specified binary output for every binary input. |
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| The read only memory can also be seen as a simple combinational Boolean network, which produces a specified output value for each input combination, i.e. for each address. Thus storing binary information at a particular address location can be achieved by the presence or absence of a data path from the selected row (word line) to the selected column (bit line), which is equivalent to the presence or absence of a device at that particular location. |
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| The two different types of implementations of ROM array are: |
- NOR-based ROM array
- NAND-based ROM array
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