PA-RISC information - since 1999

HP-RT Real-time


HP-RT was a real-time operating system from HP for its HP 9000 740 VME instrumentation computers, released from 1993 to 1997 in six versions from 1.0 to 3.0. It apparently was (also) sold as part of the HP-RT Developer's Kit that included the 743rt and high performance 744rt VME computers.

© Hewlett Packard 1997

Apparently, HP-RT was based on the real-time operating system LynxOS. It was built as a real-time operating system from scratch, had a native POSIX API and included Unix features such as protected address spaces, multiprocessing, and standard GUI. The real-time scheduling is part of the kernel with response times under 200 µs, later improveder to sub-100µs for uses such as hospital system tied to a heart monitor, or a missile tracking system.

For programming, HP-RT supported dynamic shared libraries, C/ANSI C, FORTRAN, and PA-RISC Assembly as well as third-party ADA. In releases 3.0 and later, a GUI-based debugging environment DDErt and Event Logging library (ELOG) was included.

© Hewlett Packard, HP Journal

On the software side, HP-RT supported fast file system, X and Motif clients, X11 SERVERrt, STREAMSrt (SVR 3.2), NFS,

Software development on HP-RT required the HP-RT Development Environment, 740rt VME machines, like the 742rt, but also a dedicated HP 9000 700 host machine running HP-UX for compiling and linking. The software was then downloaded to the rt VME system.

HP 74x VME products were discontinued in 2002 as customers have migrated to new solutions and platforms more rapidly than anticipated with end of support between 2003 and 2007. This included HP-RT as there were no follow-on HP PA-RISC products.

Systems support

HP-RT supported HP 9000 740 Series VME computers with rt suffix, that were almost identical to their non-rt products.

Model Processor Speed HP-RT versions
742rt PA-7100 50 MHz HP-RT 1.0 to 3.0
743rt PA-7100LC 64 MHz HP-RT 2.0 to 3.0
V743rt Agilent PA-7100LC 100 MHz HP-RT 2.1 to 3.0
744rt PA-7300LC 132-165 MHz HP-RT 3.0

Hardware support

© Hewlett Packard, HP Journal

HP-RT supported most of the on-board hardware and only very few expansion boards and devices. Some of the hardware and I/O was only supported in the last HP-RT version 3.01.

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There were six versions of HP-RT from 1.0 to 3.01 plus several minor patch releases like 2.11 that were not shipped to all customers. A break in releases was between 2.1 (1995) and 3.0 (1997) when support had to be provided for HP-UX 9 as well as the new HP-UX 10 in the HP-RT developers kit.

© Hewlett Packard, HP Journal

From inception, HP-RT was compliant with POSIX 1003.1 (operating system programming interfaces) and POSIX 1003.4 and 4a drafts (real time extensions and threads).

HP-RT is split into two parts: First, the HP-RT kernel with low-level I/O drivers, a 10ms interrupt clock, access to hardware timers (1µs) and standard OS functions such as scheduling, multitasking, memory management, IPC and kernel services. The second part, HP-RT services, contain optional higher-level functions such as NFS, TCP/IP, debuggers and development.

The HP-RT developers kits cost $9,995 at time of release. It seems HP-RT development and releasing was a bit in flux throughout the short(ish) timespan of commercial support and HP-RT ended soon after 744rt workstations and HP-UX 10.20 EOL.

HP-RT 3.0

HP-RT 3.00 was released as the last major version in January 1997. It added support for the PA-7300LC-based VME workstations 744rt/132L (no graphics yet) and updated the HP-RT operating system core significantly.

HP-RT 3.01 was the last version of HP-RT from October 1997 and added mostly hardware support, including for the 744rt/165L

HP-RT 2.0

The second HP-RT major release 2.0 was introduced in August 1994 and added support for HP 9000 743rt based on PA-7100LC processors. Besides hardware, HP-RT 2.0 added some features:

HP-RT 2.1 was released in October 1995 and added more features and support for the (Agilent) V743rt VXI workstations with 32-bit PA-7100LC processors. The 743rt (and 742rt?) workstations were still supported.

HP-RT 2.2 was released in June 1996 with several functional enhancements:

There might have been a HP-RT 2.21 that already supported 744rt/132L, the GSC second slot expansion kit and external SCSI drives and DDS tapes.

HP-RT 1.0

The first HP-RT version 1.0 was released in January 1993, it supported the 742rt VME-based workstation on PA-7100 processors.

Features of HP-RT 1.0 were:

HP-RT 1.1 was released in July 1993 and extended some HP-RT features:

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Almost all information on HP-RT has been gone from the internet for years (decades), luckily some early-2000s mirrors are available.

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