A virtual memory is partitioned into virtual partitions, each partition being subdivided into virtual sub-partitions and each sub-partition corresponding to a combination of multiple sectors of identical or different sizes of a physical memory. When an allocation request is made for a virtual memory space having a given memory size, a free partition is selected, a virtual sub-partition is selected corresponding to a combination of sectors having a minimum total size covering the given memory size of the virtual memory to be allocated, and free sectors of the physical memory are selected corresponding to the selected combination. A determination is made of a correspondence table between the selected virtual partition and the initial physical addresses of the selected free sectors, and a virtual address is generated.