12c clr reg not programmable, why?

[Don Shepherd]

(01-04-2020 07:56 PM)Csaba Tizedes Wrote:  Because it is totally useless ... Therefore no need to clear one or all of them.

Clearing a register is not a useless idea, it is a requirement if you are going to use a given register as a counter and you want to make sure it starts out as 0. This is a basic principle that new programmers learn on day one. True, you can always store 0 in any register, but if you are going to tally 5 different things in 5 registers CLR REG might come in handy. I admit that it might be a bad idea to have CLR REG command in a 12c program because it is going to clear everything including the value in X which you normally use to input a value into a program on the 12c. This would not be a problem on the HP-65 since CLR REG does not clear the stack as it does on the 12c.