In the early history of computing before the mid-1960s, there was no universal, de-facto standard for the written representation of a hexadecimal number, different computer systems used their own written presentations. Wikipedia has some examples.
The ILLIAC I (1952) computer used the uppercase letters K, S, N, J, F and L for the values 10 to 15.
The Honeywell Datamatic D-1000 (1957) used the lowercase letters b, c, d, e, f, and g whereas the Elbit 100 (1967) used the uppercase letters B, C, D, E, F and G for the values 10 to 15.
The Monrobot XI (1960) used the letters S, T, U, V, W and X for the values 10 to 15.
The Pacific Data Systems 1020 (1964) used the letters L, C, A, S, M and D for the values 10 to 15.
I was reading
alt.folklore.computers today and found a claim: The IBM S/360 was one of the major computer systems that used 'A' to 'F' to represent a hexadecimal number, and S/360 was largely responsible the popularization of this de-facto standard due to its success.
How true is this claim?