HP3000/HP 3000 FAQ

Last Updated: Thursday, February 01, 2007 02:38 PM

What's the difference (hardware) between CISC and PA-RISC HP3000 systems

2.1.1. What's the difference (hardware)

JK

The HP-3000 series of computers dates back to 1972 with the first model, the HP3000/CX which ran the MultiProgramming Executive, MPE-C operating system with 64K bytes of core memory (addressed as 32K 16-bit words). Subsequent models (Series II, Series III) added additional addressing capabilities to include additional "banks" of 64Kb memory and each model brought out a new operating system (MPE II, MPE III). All models were and have continued to be object-code compatible (at least forward-compatible) with few exceptions (most notably the change in floating-point format from the CX).

Microprocessor-based 3000's were introduced with the models 30 and 33 concurrent with a changeover of the prevalent I/O architecture to HP-IB. Later models expanded the product line to the models 40, 44, and 64 and correspondingly the MPE IV operating system. Shortly thereafter, "disc caching" came into being and the controversial "MPE V" operating system. MPE V was eventually delivered in three flavors:

* MPE V/P for existing 3x, 4x, and 6x models which was marketed as an upgrade (40-42, 44-48, and 64-68) but involved no hardware (if the memory expansion was omitted). This provided disc caching software.

* MPE V/E which *did* require hardware upgrade (to support extended CST tables, among other things) providing disc cache and extended tables.

* MPE-V R for the series II/III to give MPE-V functionality without the disc caching option (they were considered too memory constrained). This was the last release of MPE for these systems (now unsupported).

HP experimented with a 32-bit version of the HP3000 CISC-based processor code named "Vision" but it never came to market; instead they opted for the RISC-based "Spectrum" machines where the current HP3000/9xx systems have their roots. Although radically different in architecture and in their instruction sets, the "Spectrum" series maintained an imbedded "Compatibility Mode" facility which (largely but not completely) kept the forward-compatibility object code concept alive. The underlying operating system (initially called HPE internally) became MPE/XL.