NS32000
Early 32-bit CISC microprocessor family from National Semiconductor.
The NS32000, also called the 32k, is a family of microprocessors from National Semiconductor. Development started around 1980, and the series was announced at the International Solid-State Circuits Conference in April 1981. The first chip arrived in 1982, initially called the 16032 but soon renamed the 32016. It was the first general-purpose microprocessor sold that handled 32-bit data internally. While the Motorola 68000 had 32-bit registers and could perform 32-bit arithmetic, it used a 16-bit ALU for those operations, making them take twice as long as on the 32016. However, the 32016 had many bugs and often could not run at its advertised speed. These issues, combined with the fact that the similar 68000 had been available since 1980, meant the 32016 saw little market use despite strong early interest.
Several improved versions followed. The 32032, released in 1985, was essentially a bug-fixed 32016 with an external 32-bit data bus. It was about 50% faster than the 32016 but was outperformed by the 32-bit Motorola 68020, which had come out a year earlier. The 32532, released in 1987, was nearly twice as fast as the contemporary Motorola 68030, but by then most interest in microprocessors had shifted to RISC platforms, so this otherwise excellent design also saw almost no adoption. National was working on further improvements with the 32732 but eventually abandoned the effort to compete in the CPU market. Instead, the basic 32000 architecture was combined with support systems and relaunched as the Swordfish microcontroller, which had some success before being replaced by the CompactRISC architecture in the mid-1990s.
The NS32000 series originated from National’s attempt to create a single-chip implementation of the VAX-11 architecture. The VAX was famous for its highly orthogonal instruction set, where any instruction could work with any data type—for example, an ADD could add two registers, a register and a memory value, two memory values, or use a register as an offset. This flexibility was seen as the ideal for CISC design. National sued Digital Equipment Corporation in California to ensure the design was legal, but when DEC moved the case to Massachusetts (DEC’s home state), the lawsuit was dropped, and the Series 32000 architecture was developed instead.
- First member released
- 1982
- Original name
- 16032, later renamed 32016
- Data bus width (32016)
- 16-bit
- Alu width
- 32-bit
- Package (32016)
- 48-pin DIP
- Improved version (1985)
- 32032 with 32-bit external data bus
- Later version (1987)
- 32532
Lore & Background
The NS32000 series traces its history to an effort by National Semiconductor to produce a single-chip implementation of the VAX-11 architecture. National took Digital Equipment Corporation (DEC) to court in California to ensure the legality of the design, but when DEC had the lawsuit moved to Massachusetts, DEC's home state, the lawsuit was dropped and the Series 32000 architecture was developed instead. Although the new instruction set architecture was not VAX-11 compatible, it did retain its highly 'orthogonal' design philosophy, where every instruction could be used with any type of data.
The first chip, the 32016, had a 32-bit ALU but a 16-bit data bus, requiring two machine cycles to load a single 32-bit word. It could be used with the NS16082 memory management unit (MMU) for 24-bit virtual memory support. The 32016 contained many bugs and often could not be run at its rated speed. These problems, and the presence of the otherwise similar Motorola 68000 which had been available since 1980, led to little use in the market despite considerable early interest.
Several improved versions followed, including 1985's 32032 which was essentially a bug-fixed 32016 with an external 32-bit data bus, offering about 50% better speed. The 32532, released in 1987, outperformed the contemporary Motorola 68030 by almost two times, but by this time most interest in microprocessors had turned to RISC platforms. National was working on further improvements in the 32732, but eventually gave up attempting to compete in the CPU space. The basic 32000 architecture was combined with several support systems and relaunched as the Swordfish microcontroller, which had some success before being replaced by the CompactRISC architecture in the mid-1990s.
Reader's Guide
The NS32000 series is notable for being the first general-purpose microprocessor to use 32-bit data internally, with a 32-bit ALU that allowed 32-bit and 16-bit instructions to complete in the same time, unlike the Motorola 68000 which used a 16-bit ALU. However, the 32016's 16-bit data bus and pin-sharing with the address bus introduced delays, and early versions were plagued by bugs that often prevented operation at rated speed. Despite significant early interest, the 32016 saw little market use due to these issues and competition from the earlier 68000.
Improved versions like the 32032 and 32532 addressed bugs and improved performance, with the 32532 outperforming the Motorola 68030 by almost two times. However, by the late 1980s, the market had shifted toward RISC platforms, and the otherwise excellent 32532 saw almost no use. National eventually abandoned CPU development and repurposed the architecture into the Swordfish microcontroller, which achieved some market success before being superseded by the CompactRISC architecture in the mid-1990s. The series thus represents a technically advanced but commercially unsuccessful CISC design that was overtaken by both competitor products and the RISC paradigm shift.
Did You Know?
- The first member, the 32016, was originally called the 16032 before being renamed.
- The architecture was later repurposed into the Swordfish microcontroller, which had some market success.
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