When you get a little bit more familiar with the instruction set, you can try some minor optimisation:
To avoid the need for clearing carry before subb, when subtracting constants, you can add the negative of it instead - just remember, that the meaning of carry will be the opposite:

; A - original code
   ADD   A,#-20h
   JNC   PRN_CHAR_END     ; code is below 0x20 so non-printable

(Btw. AVRs by design don't have add a constant instruction - so one has to use subtract instead... (or a "helper" register).)

You can also completely avoid manipulation with the "pointer" simply by offsetting the table address when loading into dptr; but if you are not absolutely sure that the input value will be above 20h, there is little gained from this as you need to check it anyway.

Jan Waclawek