unsigned char question

[richard boaz]

my question regards the declaration of a character array as being unsigned
as in:
	unsigned char	directory[65];

i've been handed down a program which declares all of the arrays being used
to store only ascii characters as unsigned.  by definition, unsigned gives
me use of the upper-most bit, yet ascii only accesses the lowest 7 bits.
someone has suggested to me that the compiler converts all signed variables
to a value of long, yet i still fail to see how this helps me in the case of
character strings.  anybody have a clue?  all responses are appreciated.

thanks in advance,
richard