ld hl,buffer
 push hl
_inp:
 bcall(_GetCSC)
 cp skEnter
 jr z,inputDone
 cp 0xa
 jr c, _inp
 ld hl,_table
 ld e,a
 ld d,0
 add hl,de
 ld a,(hl)
 or a
 jr z,_inp  ; Not a valid character, ignore
 ex (sp),hl
 ld (hl),a
 inc hl
 ex (sp),hl
 jr _inp
inputDone:
 pop hl
;...

_table:
 ; keycode mapping table, from 0xA
 ; xref ti83plus.inc scan codes (from skAdd)
 .db '"','W','R','M','H'