Source : Free On-Line Dictionary of Computing

HPL
     
        Language used in HP9825A/S/T "Desktop Calculators", 1978(?)
        and ported to the early Series 200 family (9826 and 9836,
        68000).  Fairly simple and standard, but with extensive I/O
        support for data acquisition and control (BCD, Serial, 16 bit
        custom and {IEEE 488} interfaces), including interrupt
        handling.  Currently owned by Structured Software Systems.
        "HPL Operating Manual for Series 200, Models 216, 226 and
        235\6", HP 98614-90010, Jan 1984.