The answer depends on what level you are talking about and what kind of computer you are talking about.
A standard PC running a Microsoft Windows OS is going to identify the physical drives by numbers, starting with "drive 0".
The physical drives can then be broken into virtual drives and assigned drive letters.
You will usually be using letters to work with the drives.
Bytes are the units that measure the capacity of the drive, so the bytes are not really used to identify the drive.
ASCII
hi
It is an input device for a computer with letters, numbers and symbols on it. It can also be used in playing music.
Individual letters, numbers or special symbols such as @#$%^& found on a computer keyboard.
A combination of letters and numbers and symbols is a character set. To use a formula to combine letter and numbers and symbols is known as concatenation.
In computer programming, a string can be made up of; all numbers (a numeric string,) all letters, (an alphabetic string,) or a mixture of numbers, letters, and symbols, (an alphanumeric string.)
OUIJA
because of my nan
It makes clear that the following symbols should be read as numbers. Some Braille symbols do double duty as letters and numbers, and there are symbols that flag that the following should be read as numbers or as letters. en.m.wikipedia.org/wiki/English_Braille#Contractions
Algebra makes use of letters and mathematical symbols.
Just use letters and numbers, no symbols.
one that has a lot of random letters, numbers, and symbols