Intel i860

[1] It was released with considerable fanfare, slightly obscuring the earlier Intel i960, which was successful in some niches of embedded systems.

The i860 combined a number of features that were unique at the time, most notably its very long instruction word (VLIW) architecture and powerful support for high-speed floating-point operations.

In traditional architectures these duties were handled at runtime by a scheduler on the CPU itself, but the complexity of these systems limited their application in early RISC designs.

As a result of its architecture, the i860 could run certain graphics and floating-point algorithms with exceptionally high speed, but its performance in general-purpose applications suffered and it was difficult to program efficiently (see below).

The entire i860 design was based on the compiler efficiently handling this task, which proved almost impossible in practice.

[10] The later Itanium architecture, also a VLIW design, suffered again from the problem of compilers incapable of delivering sufficiently optimized code.

Confusingly, the 860 number has since been re-used for a motherboard control chipset for Intel Xeon (high-end Pentium) systems and a model of the Core i7.

Andy Grove suggested that the i860's failure in the marketplace was due to Intel being stretched too thin: We now had two very powerful chips that we were introducing at just about the same time: the 486, largely based on CISC technology and compatible with all the PC software, and the i860, based on RISC technology, which was very fast but compatible with nothing.

It was used, for instance, in the NeXTdimension, where it ran a cut-down version of the Mach kernel running a complete PostScript stack.

In this role, the i860 design worked considerably better, as the core program could be loaded into the cache and made entirely "predictable", allowing the compilers to get the ordering right.

Pixar produced a custom version of RenderMan to run on the card that ran approximately four times faster than the 386 host.

Good performance was obtained from the i860 by supplying customers with a library of signal processing functions written in assembly language.

The hardware packed up to 360 compute nodes in 9U of rack space, making it suitable for mobile applications such as airborne radar processing.

During the early 1990s, Stratus Technologies built i860-based servers, the XA/R series, running their proprietary VOS operating system.

[18] Also in the 1990s, Alliant Computer Systems built their i860-based FX/800 and FX/2800 servers, replacing the FX/80 and FX/8 series that had been based on the Motorola 68000 ISA.