Apple Partition Map (APM)
| Format | Apple Partition Map (APM) |
|---|---|
| Short name | APM |
| Category | filesystem |
| Platforms | macOS |
| Crush support | Not yet supported |
| Status | Reviewed |
| Last reviewed | 2026-10-05 |
Forensic relevance
The Apple Partition Map partitioning scheme used by classic Macintosh systems and PowerPC-based Macs, and also encountered on some older Apple media and disk images. The partition map begins with a driver descriptor record in block 0, which also states the block size, followed by partition map entries starting in block 1 (512-byte entries, or 2048-byte entries on media such as CD-ROMs). Each entry contains the partition name, partition type, starting block, partition size and additional metadata. The map describes itself as a partition of type Apple_partition_map; other common partition types include Apple_HFS, Apple_Driver43 and Apple_Free. The partition map is forensically important because it defines the original partition layout and boundaries, allowing individual partitions to be located and interpreted correctly in a disk image, including partitions that may not currently be mounted or recognized by a modern operating system.
Signatures
| Offset | Hex | ASCII (non-printable as .) | Description |
|---|---|---|---|
| offset unknown | 45 52 | ER | Driver descriptor signature 'ER' in block 0 (too short to identify on its own) |
| offset 512 (0x200) | 50 4D | PM | Partition map entry signature 'PM' in block 1 |
| offset 2048 (0x800) | 50 4D | PM | Partition map entry signature 'PM' in block 1 on 2048-byte block media (e.g. CD-ROM) |
| offset 560 (0x230) | 41 70 70 6C 65 5F 70 61 72 74 69 74 69 6F 6E 5F 6D 61 70 | Apple_partition_map | Partition type 'Apple_partition_map' of the first map entry, which describes the map itself |
| offset 2096 (0x830) | 41 70 70 6C 65 5F 70 61 72 74 69 74 69 6F 6E 5F 6D 61 70 | Apple_partition_map | Partition type 'Apple_partition_map' of the first map entry on 2048-byte block media |
Known extensions
None recorded
References
- Apple Partition Map (APM) (libyal/libvsapm) https://github.com/libyal/libvsapm/blob/main/documentation/Apple%20partition%20map%20(APM)%20format.asciidoc
Cite this entry
Crush Format Reference, “Apple Partition Map (APM)”. https://kalink0.github.io/crush-forensics/formats/apm/ — source: crush/data/build_formats_db.py at commit 640a2a9928f4e36a976b89901512a8dce824d093, built 2026-10-21 06:46:19 UTC.
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