Direct Mapped Cache Possibilities

A direct-mapped cache is a type of cache memory organization where each block of main memory is mapped to only one specific cache location. In other words, each memory block can only be stored in a specific cache location determined by the memory address. This mapping is determined by the least significant bits of the memory address.

To calculate the number of possibilities of mapping in a direct-mapped cache, we need to consider the number of cache locations available and the number of memory blocks that need to be mapped.

1. Cache Locations:
- In a direct-mapped cache, the number of cache locations is fixed and determined by the cache design. Let's assume there are 'N' cache locations available.

2. Memory Blocks:
- The number of memory blocks that need to be mapped depends on the size of the main memory. Let's assume there are 'M' memory blocks.

3. Mapping Possibilities:
- Each memory block can only be mapped to one specific cache location. Therefore, the number of mapping possibilities is equal to the number of memory blocks, 'M'.

4. Example:
- Suppose we have a direct-mapped cache with 8 cache locations (N = 8) and a main memory with 16 memory blocks (M = 16).
- In this case, each memory block can be mapped to one of the 8 cache locations, resulting in 16 mapping possibilities.
- The mapping is determined by the least significant bits of the memory address.

- Let's consider an example memory address: 00101101 (5 bits).
- The least significant 3 bits (101) determine the cache location.
- If the cache location 101 is available, the memory block can be mapped to it.

Conclusion:
In a direct-mapped cache, the number of possibilities of mapping is equal to the number of memory blocks that need to be mapped. Therefore, the correct answer is option 'A' - 1 possibility.