Memory Allocation

Memory Allocation

Contiguous memory allocation with variable partitions: a queue of requests (A=120 allocates 120 units to A, -A frees A) is served by First, Best, Worst or Next Fit. The memory map shows holes, processes and reserved OS blocks; during a step the candidate holes are checked one by one. The history underneath has one row per request, the side panel lists the holes in address order and every process’s state.

How to use

• Pick an algorithm and an initial hole layout (Default, Fragmented, Large).
• Edit the requests directly, add (+) or clear (×) them (at most 24), or load a preset.
• ▶ plays; the step buttons move one request back or forward, or jump to the start or end. Click a history row to jump to it.
• Compare runs all four algorithms on the same queue and shows their final memory maps and external fragmentation.

Algorithms

First

First hole large enough.

Best

Smallest hole large enough.

Worst

Largest hole.

Next

First Fit from the cursor (after the last allocation), wrapping around.

Ext. frag

Total free minus the largest hole.

Queue

A=120

Allocate 120 units to A.

-A

Free A; neighbouring holes merge.

Legend

Keys