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Step 1. The Memory Map
A memory map is usually a one-dimensional table.
A memory map indicates which types of memory (or which memory chips) occupies which memory space.
The memory map indicates
- how many memory devices are in the system,
- their starting addresses, and
- the memory size of each memory device.
No two memory devices should occupy the same memory space.
The starting address of each chip is usually an integer multiple of the address size of the memory chip.
To design a memory module, we need to specify first which addressable memory space is occupied by what types of memory chips. A mechanism used for this purpose is called a memory map. A memory map is usually a one-dimensional table. The size of the table does not exceed the microprocessor's addressable memory space. Each entry of the table corresponds to one memory location.
It is the duty of the computer system designer to specify what memory chip is allocated to what memory address. The rule for specifying the memory map is that different memory chips never occupy the same memory address. It is highly advisable that the starting address of each memory chip be an integer multiple of the addressable space of the chip. Following this advice can make the address decoding circuit simpler. This will be discussed in more detail later.