Byte variable :
The assembler directive that defines a byte variable takes the following form:
name DB . initial_value
where the pseudo-op DB stands for "Define Byte"
for example ,
This directive causes the assembler to associate a memory byte with the name ALPHA, and initialize it to 4,A question mark("?") used in place of an initial value sets aside an uninitialized byte ; for example ,
The decimal range of initial values that can be specified is -128 to 127 if a signed interpretation is being given ,or 0 to 255 for an unsigned interpretation .These are the ranges of values that fit in a byte.