If it doesn't have an Enter key, it's not RPN

[Michael de Estrada]

I just won another auction for an RPN calculator. This time it's a Commodore Minuteman 6X, which differs from the model 6 with the addition of a proper enter key. The enter key serves to initialize a chained postfix operation and can only be used once, since the stack has only two levels and does not get raised after the first entry. This calculator includes its box and all documentation, including an inspection report, which is signed with the initials D B. Hmmm, I wonder who that might be ?