What is PRC? Palm/Mobipocket Ebook Format Explained
A Palm-database container used by Mobipocket and PalmDOC ebooks.
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What is PRC?
PRC (Palm Resource/Database file) is a container format originating from the Palm OS platform that has been widely used to store ebooks. In the ebook context, PRC files most commonly hold Mobipocket or PalmDOC content for reading on handheld devices.
Technically, a PRC ebook is a Palm Database (PDB) file containing compressed text and, for Mobipocket, the same XHTML-based content found in MOBI files. Because Mobipocket and MOBI share this container, .prc and .mobi files are closely related, and the format was carried into early Kindle and Mobipocket Reader workflows.
How PRC Files Work
A PRC file is structurally a Palm Database (PDB), a record-oriented container inherited from Palm OS in which an application's data is split into numbered records preceded by a header and record-offset table.[2] For ebooks, the first record holds metadata and compression settings while subsequent records carry the compressed text, commonly using PalmDOC-style compression.[1]
Relationship to Mobipocket and MOBI
Mobipocket built its ebook format on this Palm container, embedding XHTML-based content together with an indexed structure for navigation.[3] Because the underlying container is identical, a Mobipocket book may carry either a .prc or .mobi extension, and the two are largely interchangeable.[1]
Legacy and Limitations
Amazon acquired Mobipocket and carried the format into early Kindle workflows before moving to AZW and later KF8/EPUB-based formats.[3] As a Palm-era container the format predates modern reflowable styling, and complex layout or rich media support is limited compared with current ebook standards.[2]
MKV Technical Specifications
PRC vs Other Ebook Formats
| Feature | PRC | MOBI | EPUB |
|---|---|---|---|
| Type | Palm/Mobipocket container[1] | Mobipocket ebook | Open ebook |
| Relation | Mobipocket variant[2] | Same engine | Different standard |
| Layout | Reflowable | Reflowable | Reflowable |
| Open/proprietary | Proprietary[3] | Proprietary | Open standard |
| Best for | Legacy Mobipocket/Palm | Older Kindle | Cross-reader books |
PRC is essentially a Mobipocket file in a Palm container, so it shares MOBI's behavior, whereas EPUB is the open, broadly supported alternative.
Advantages & Disadvantages
Advantages
PRC uses Palm's database structure with compressed text, producing small ebook files suited to limited-memory devices.
The format was readable across Palm OS devices and the Mobipocket Reader on multiple platforms.
Mobipocket PRC files share the MOBI container, so many MOBI tools can read or convert them.
Content reflows to the device screen, adapting to different display sizes.
Disadvantages
PRC is tied to the Palm OS and Mobipocket era, both long discontinued, limiting modern relevance.
The .prc extension is also used for Palm application databases, which can cause confusion about file contents.
As a PalmDOC/Mobipocket container, PRC supports only simple text formatting compared with modern ebook formats.
Common Use Cases
PRC is encountered mainly as a legacy handheld ebook format.
Palm OS ebooks | FileFormer
Documents and books distributed for Palm handhelds used the PRC/PalmDOC container.
Mobipocket Reader content | FileFormer
Mobipocket distributed ebooks as PRC files readable on phones, PDAs, and desktops.
Conversion to modern formats | FileFormer
Tools like Calibre convert legacy PRC ebooks to EPUB or MOBI for current devices.
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Try Ebook Converter FreeFrequently Asked Questions
What is a PRC file?
In ebooks, a PRC file is a Palm Database container holding Mobipocket or PalmDOC text content for reading on handheld devices.
Is PRC the same as MOBI?
Mobipocket PRC files use the same Palm Database container as MOBI, so the two are closely related and often interchangeable for Mobipocket content.
Why do some PRC files not open as ebooks?
The .prc extension is also used for Palm OS application databases, so a PRC file may contain a program rather than an ebook.
How do I read a PRC ebook today?
You can convert PRC ebooks to EPUB or MOBI using software like Calibre, since native Palm and Mobipocket readers are largely obsolete.
Is PRC still used?
PRC is a legacy format tied to the Palm and Mobipocket era; it has largely been replaced by MOBI, AZW, and EPUB.