RISC-based systems were known as the "XL" versions, while the earlier CISC models retroactively became the "Classic" series. The two sold in tandem for a short period, but the XL series largely took over in 1988. Identical machines running HP-UX instead of MPE XL were known as the HP 9000.

HP initially announced the systems would be designated to be at end-of-life at HP in 2006, but extended that several times to 2010. The