RADIX 50[1][2][3] or RAD50[3] (also referred to as RADIX50,[4] RADIX-50[5] or RAD-50), is an uppercase-only character encoding created by Digital Equipment Corporation (DEC) for use on their DECsystem, PDP, and VAX computers.
[2] Some strings in DEC's 16-bit systems were encoded as 8-bit bytes, while others used RADIX 50 (then also called MOD40).
Where RADIX 50 was used for filenames stored on media, the code points represent the $, %, * characters, and will be shown as such when listing the directory with utilities such as DIR.
Some early documentation for the RT-11 operating system considered the code point 29 to be undefined.
[3] The use of RADIX 50 was the source of the filename size conventions used by Digital Equipment Corporation PDP-11 operating systems.