sjasmplus version of ZX Spectrum Next dot command "ECHO"

ECHO.asm

        OUTPUT "ECHO"
        ORG     8192
Start:  ex      de,hl
        ld      a,d
        or      e
        ret     z       ; DE == 0, no pointer to arguments
Print:  ld      a,(de)
        or      a
        ret     z       ; zero byte end of command line
        cp      13
        ret     z       ; "enter" ending command line
        cp      ':'
        ret     z       ; ":" ending command line
        inc     de      ; move pointer to next character
        rst     16      ; print current character in register A
        jr      Print   ; loop until command line ends