PsiFS: File System

Character Mappings

Character Mappings

PsiFS attempts to preserve special characters in filenames. Unfortunately, the standard character sets of RISC OS (Latin1), SIBO (code page 850) and EPOC (Windows ANSI character set) are all different, so not all filenames can be preserved unchanged.

If a RISC OS file is copied to a SIBO or EPOC device then some unmappable characters may be converted to "_" (underscore) symbols. In the opposite direction, from a SIBO or EPOC device to RISC OS, characters without a direct mapping are converted to a unique sequence of characters. This ensures that SIBO or EPOC files can be copied and restored without any change of name.

It is beyond the scope of this documentation to fully describe the mapping between the various character sets. However, the following special symbols are mapped in a similar manner to DOSFS:
RISC OShard space<>#?./
SIBO or EPOCspace$^?#\.

Finally, SIBO only supports upper-case filenames. PsiFS converts such names so that the first character is upper-case and all other characters are lower-case. This is similar to the approach used by Windows 95/98 to display old MS-DOS style filenames.


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