Byte conversion Algorithm

Hi All,

I am need of developing a conversion algorithm that will convert a 3 byte numeric value to 2 byte alphanumeric/alphabetic/numeric value and viceversa. Any one of you had a similar requirement ?

For eg.

001 - 01
002 - 02
003 - 03
...
...
...
099 - 99
100 - A1
...
270 - AA

etc...

Something of this sort. Can you please help me out. Also Iam not suppossed to hard code these mapped values with the cobol module nor I can store these values in any lookup file.