ARCHIMEDES ISO 9660 extension

This article covers an ISO 9660 extension that contains metadata specific to Acorn / Archimedes / RISC OS systems.

Format details
The extension is a 32-byte data element located in the "system use" area of each directory record. It begins with the signature "".

According to a cdrtools patch, the format is:

0-9  "ARCHIMEDES" 10-13 Load address 14-17 Execution address 18-21 Attributes 22-31 Reserved

The load/execution/attributes fields are 32-bit little-endian integers. Following a RISC OS convention, the load/execution fields usually contain the file type and a timestamp. It is comparable to the ZIP "AC" extensible data field, for example.

Attributes bit 0x100 indicates that the original filename began with a "!" character.

Sample files
The extension is common on RISC OS CD-ROMS.
 * APDL Public Domain CD 2 → APDL_PD2A.iso