An old timetable had about 29 codes per page and had 16 pages = ~ 464 codes. That is give or take a few. There are several codes not used any more but may be in the computer system. Since the Amtrak computer system is very ancient it could be the binary number of 512 might limit number of codes???s
A computer guru might know if all the possible additional stations might overload the reservation system?
It is a 3 character code. There is no doubt a hard field length limit of 3 characters. Hard character field lengths were common on older systems, more modern systems use variable type string without the hard limit.
They would not have been encoded as a single binary number, but 3 individual 7 or 8 bit characters. Original ASCII character encoding was 7 bit. Expanded ASCII or UTF-8 character encoding is 8 bit, 8 bits being the commonly accepted byte length today. If I recall correctly, EBCDIC character encoding (used on IBM mainframes) also expressed characters in 7 or 8 bits.
Depending on the character encoding byte length used, the field is either 21 or 24 bits long.
The limit is 3 characters, call it 3 7 or 8 bit fields. I will use 8 bit since that is the common standard byte and the one I was used to seeing through my entire career.
CHI is:
"C" = b'01000011', x'43', d'67'
"H" = b'01001000', x'48',d'72'
"I" = b'01001001', x'49', d'73'
in ASCII/UTF-8 character encoding.
b being the raw binary, x the hexadecimal notation, the value of each half byte (4 bits), and d being 8 bit binary field expressed as a decimal number (pretty useless. Hex is what people use if they need to get down to having to deal with the raw bits).
The limit is the number of 3 character alpha or alphanumeric permutations (depending if numerics are valid characters for the field).
Alphanumeric 42,840 permutations.
Alphabetic only 15,600 permutations.
