Depletion-load NMOS logic: Difference between revisions

Revision as of 12:52, 5 October 2020

Revision as of 18:50, 5 October 2020

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there were never any standardized [[logic family|logic families]] in nMOS, such as the [[transistor-transistor logic|bipolar]] [[7400 series]] and the [[CMOS]] [[4000 series]], although designs with several second source manufacturers often achieved something of a de facto standard component status. One example of this is the nMOS [[Intel 8255|8255 PIO]] design, originally intended as an 8085 peripheral chip, that has been used in Z80 and x86 [[embedded system]]s and many other contexts for several decades. Modern low power versions are available as CMOS or BiCMOS implementations, similar to the 7400-series.

===TheIntel HMOS processes===

Intel's own depletion-load NMOS process was known as '''HMOS''', for ''High density, short channel MOS''. The first version was introduced in late 1976 and first used for their [[static RAM]] products,<ref>''See http://lark.tu-sofia.bg/ntt/eusku/readings/art_1.pdf''</ref> it was soon being used for faster and/or less power hungry versions of the 8085, 8086, and other chips.

In the early to mid-1980s, [[CMOS]] was still quite slow and used mostly for the [[4000 series]], [[Static RAM]]s, and low-power [[Application-specific integrated circuit|ASIC]]s (such as [[watch#Digital|watch]] and [[calculator]] ICs). Advanced processes for depletion-load nMOS, such as Intel's family of scaled '''HMOS''' (''High density, short channel MOS'') processes were therefore used for most microprocessors, certain types of memories, and many support and peripheral ICs. The first nMOS process called HMOS (late 1976) was originally used for Intel's then central [[static RAM]] products. Although primarily intended for fast SRAM,<ref>''See http://lark.tu-sofia.bg/ntt/eusku/readings/art_1.pdf''.</ref> it was soon employed also for faster and/or less power hungry versions of the 8085, 8086, and other chips. HMOS was also licensed to other manufacturers, such as Motorola, which used it to manufacture the [[Motorola 68000]] series, for instance. According to Intel, HMOS-II (1979) provided twice the density and four times the speed/power product over other typical contemporary depletion-load nMOS processes.<ref>See for instance: ''Leo J.Scanlon The 68000 Principles and programming.''</ref> HMOS, HMOS II, HMOS III, and HMOS IV were together used for many different kinds of processors; the [[8085]], [[8048]], [[8051]], [[8086]], [[Intel 186|80186]], [[Intel 286|80286]], and many others, but also for several generations of the same basic design, see [[datasheet]]s.

HMOS continued to be improved and went through four distinct generations. According to Intel, HMOS II (1979) provided twice the density and four times the speed/power product over other typical contemporary depletion-load nMOS processes.<ref>See for instance: ''Leo J.Scanlon The 68000 Principles and programming.''</ref> This version was widely licensed by 3rd parties, including (among others) [[Motorola]] who used it for their [[Motorola 68000]], and [[Commodore Semiconductor Group]], who used it for their [[CSG 8502]] die-shrunk [[MOS 6502]].

The original HMOS process, later referred to as HMOS I, had a channel length of 3 microns, which was reduced to 2 for the HMOS II, and 1.5 for HMOS III. By the time HMOS III was introduced in 1982, Intel had begun a switch to their [[CHMOS]] process, a [[CMOS]] process using design elements of the HMOS lines. One final version of the system was released, HMOS-IV. A significant advantage to the HMOS line was that each generation was deliberately designed to allow existing layouts to die-shrink with no major changes. Various techniques were introduced to ensure the systems worked as the layout changed.<ref>{{cite conference |conference=ISSCC 82 |date=1982 |title=HMOS III Technology}}</ref><ref>{{cite journal |journal=IEEE Journal of Solid-State Circuits |title=HMOS III Technology |date=October 1982}}</ref>

HMOS, HMOS II, HMOS III, and HMOS IV were together used for many different kinds of processors; the [[8085]], [[8048]], [[8051]], [[8086]], [[Intel 186|80186]], [[Intel 286|80286]], and many others, but also for several generations of the same basic design, see [[datasheet]]s.

===Further development===