18 Facts About IAPX 432

IAPX 432 is a discontinued computer architecture introduced in 1981.

Unlike the 8086, which was designed the following year as a successor to the 8080, the iAPX 432 was a radical departure from Intel's previous designs meant for a different market niche, and completely unrelated to the 8080 or x86 product lines.

IAPX 432 project is considered a commercial failure for Intel, and was discontinued in 1986.

IAPX 432 was referred to as a "micromainframe", designed to be programmed entirely in high-level languages.

The instruction set architecture was entirely new and a significant departure from Intel's previous 8008 and 8080 processors as the iAPX 432 programming model is a stack machine with no visible general-purpose registers.

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Intel iMAX IAPX 432 is a discontinued operating system for the IAPX 432, written entirely in Ada, and Ada was the intended primary language for application programming.

The iAPX 432 enlarged address space over the 8080 was limited by the fact that linear addressing of data could still only use 16-bit offsets, somewhat akin to Intel's first 8086-based designs, including the contemporary 80286 .

Intel's IAPX 432 project started in 1976, a year after the 8-bit Intel 8080 was completed and a year before their 16-bit 8086 project began.

The IAPX 432 project was initially named the 8800, as their next step beyond the existing Intel 8008 and 8080 microprocessors.

In contrast, the IAPX 432 had no software compatibility or migration requirements.

In many cases, the iAPX 432 had a significantly slower instruction throughput than conventional microprocessors of the era, such as the National Semiconductor 32016, Motorola 68010 and Intel 80286.

For instance the iAPX 432 included a very expensive inter-module procedure call instruction, which the compiler used for all calls, despite the existence of much faster branch and link instructions.

An outcome of the failure of the IAPX 432 was that microprocessor designers concluded that object support in the chip leads to a complex design that will invariably run slowly, and the IAPX 432 was often cited as a counter-example by proponents of RISC designs.

Since the iAPX 432 there has been only one other attempt at a similar design, the Rekursiv processor, although the INMOS Transputer's process support was similar — and very fast.

Intel had spent considerable time, money, and mindshare on the IAPX 432, had a skilled team devoted to it, and was unwilling to abandon it entirely after its failure in the marketplace.

IAPX 432 instructions have variable length, between 6 and 321 bits.

IAPX 432 has hardware and microcode support for object-oriented programming and capability-based addressing.

The iMAX IAPX 432 operating system includes the software portion of the garbage collector.