PRC (Palm OS)

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PRC (Palm Resource Code) is a container format for code databases in Palm OS, Garnet OS and Access Linux Platform. Its structure is similar to PDB databases.[1] Usually, a PRC file is a flat representation of a Palm OS application that is stored as forked database[clarification needed] on the PDA.

PRC files are also used by the Mobipocket e-book-reader (here sometimes referred to as MOBI format[2]). The AZW format of Amazon's Kindle reading device is in turn a DRM-restricted form of the Mobipocket format.

On Palm OS, PRC files are used for applications, localized resources (overlays) and shared libraries.[1]

Structure of PRC file[edit]

In its essence, a PRC file is similar to a classic Mac OS application. It contains a PRC header, PRC resource headers and PRC resources.[3]

PRC Header
PRC Resource Header
PRC Resources

PRC Header[edit]

The PRC header is located at the beginning of the file and contains meta-information on the file:[3]

Offset Name Type Size
0x00 name char 32 Bytes
0x20 flags integer 2 Bytes
0x22 version integer 2 Bytes
0x24 creation time 32bit integer - PDB Datetime 4 Bytes
0x28 modification time 32bit integer - PDB Datetime 4 Bytes
0x2c backup time 32bit integer - PDB Datetime 4 Bytes
0x30 mod_num integer 4 Bytes
0x34 app_info integer 4 Bytes
0x38 sort_info integer 4 Bytes
0x3c type integer 4 Bytes
0x40 creator integer 4 Bytes
0x44 unique_id_seed integer 4 Bytes
0x48 next_record_list integer 4 Bytes
0x4c num_records integer 2 Bytes

PRC Resource Header[edit]

For every resource (specified by num_records), there is a resource header containing:[3]

name type notes size
name char Name of the resource 4 bytes
ID integer ID number of the resource 2 bytes
offset integer Pointer to resource data 4 bytes

PRC Resources[edit]

Every application contains al least a Code #0 resource with size information and jump tables, a Code #1 resource with executable code and data resources containing pre-initialized values of global variables in compressed form.[3] Other resources that may be contained are forms, form objects, alerts and multimedia data, e. g. images and sounds.


  1. ^ a b N. Rhodes, J. McKeehan. Palm OS Programming, Second Edition, O'Reilly, 2001, ISBN 1-56592-856-3.
  2. ^ MobileRead Wiki: Reference for the MOBI format
  3. ^ a b c d Theodore Ts'o (2000) The PRC Format. Accessed on 2009-03-07