Intel i960

Intel's i960 (or 80960)was a RISC-based microprocessor design that became popular during the early 1990s as an embedded microcontroller, becoming a best-selling CPU in that field, along with the competing AMD 29000. In spite of its success, Intel dropped i960 marketing in the late 1990s as a side effect of a settlement with DEC in which Intel received the rights to produce the StrongARM CPU. The processor continues to be used in a few military applications.

Origin

The i960 design was started as a response to the failure of Intel's iAPX 432 design of the early 1980s. The iAPX 432 was intended to directly support high-level languages that supported tagged, protected, garbage-collected memory — such as Ada and Lisp — in hardware. Because of its instruction-set complexity, its multi-chip implementation, and design flaws, the iAPX 432 was very slow in comparison to other processors of its time.

In 1984 Intel and Siemens started a joint project, ultimately called BiiN, to create a high-end fault-tolerant object-oriented computer system programmed entirely in Ada. Many of the original i432 team members joined this project, though a new lead architect was brought in from IBM, Glenford Myers. The intended market for the BiiN systems were high-reliability computer users such as banks, industrial systems and nuclear power plants.

Intel's major contribution to the BiiN system was a new processor design, influenced by the protected-memory concepts from the i432. The new design included a number of features to improve performance and avoid problems that had led to the downfall of the i432, which resulted in the i960 design. The first 960 processors entered the final stages of design, known as taping-out, in October 1985 and were sent to manufacturing that month, with the first working chips arriving in late 1985 and early 1986.

The BiiN effort eventually failed, due to market forces, and the 960MX was left without a use. Myers attempted to save the design by outlining several subsets of the full capability architecture created for the BiiN system. He tried to convince Intel management to market the i960 (then still known as the "P7") as a general-purpose processor, both in place of the Intel 80286 and i386 (which taped-out the same month as the first i960), as well as the emerging RISC market for Unix systems, including a pitch to Steve Jobs's for use in the NeXT system. Competition within and outside of Intel came not only from the i386 camp, but also from the i860 processor, yet another RISC processor design emerging within Intel at the time.

Myers was unsuccessful at convincing Intel management to support the i960 as a general-purpose or Unix processor, but the chip found a ready market in early high-performance 32-bit embedded systems. The protected-memory architecture was considered proprietary to BiiN and wasn't mentioned in the product literature, leading many to wonder why the i960MX was so large and had so many pins labeled "no connect".