Methods of memory allocation include contiguous allocation, where each file occupies contiguous disk blocks, linked allocation, where each file is stored as a linked list of disk blocks that can be scattered, and indexed allocation. Contiguous allocation allows for simple random access but is wasteful of space and does not allow files to grow, while linked allocation manages space efficiently but does not allow random access and requires mapping between blocks.

1. METHODS OF MEMORY ALLOCATION
• An allocation method refers to how disk blocks are allocated for
files:
• Contiguous allocation
• Linked allocation
• Indexed allocation

2. CONTIGUOUS ALLOCATIION
• Each file occupies a set of contiguous blocks on the disk
• Simple – only starting location (block #) and length (number of blocks)
are required
• Random access
• Wasteful of space (dynamic storage-allocation problem)
• Files cannot grow

3. Contiguous allocation of disk space

4. LINKED ALLOCATION
• Each file is a linked list of disk blocks: blocks may be scattered
anywhere on the disk.
• Simple – need only starting address
• Free-space management system – no waste of space
• No random access
• Mapping
block = pointer

5. Linked allocation of disk space