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PMOS clock IC, 1974. PMOS or pMOS logic (from p-channel metal–oxide–semiconductor) is a family of digital circuits based on p-channel, enhancement mode metal–oxide–semiconductor field-effect transistors (MOSFETs).
One example is the Philips NORBIT family of logic building blocks. The PMOS and I 2 L logic families were used for relatively short periods, mostly in special purpose custom large-scale integration circuits devices and are generally considered obsolete. For example, early digital clocks or electronic calculators may have used one or more PMOS ...
Alternatively, rather than static logic gates, dynamic logic such as four-phase logic was sometimes used in processes that did not have depletion-mode transistors available. For example, the 1971 Intel 4004 used enhancement-load silicon-gate PMOS logic , and the 1976 Zilog Z80 used depletion-load silicon-gate NMOS.
PMOS (or pMOS) may refer to: PMOS logic; n-channel MOSFET; Prime Minister's Official Spokesman; Primary Military Occupational Specialty; postmarketOS, a free and open ...
Current mode logic (CML), or source-coupled logic (SCL), is a digital design style used both for logic gates and for board-level digital signaling of digital data.. The basic principle of CML is that current from a constant current generator is steered between two alternate paths depending on whether a logic zero or logic one is being represented.
Three-state logic: Consists of transistors to source and sink current in both logic states, as well as a control to turn off both transistors to isolate the output. This differs from open collector/drain output, which only use a single transistor that can only disconnect the output or connect it to ground.
PMOS logic required large amounts of power; the PPS-8 ran on a -17 VDC power supply and also needed separate -12V, +5V and ground. [1] The circuitry dissipated so much power that the chip could not generate a strong enough clock signal internally, and the clock had to be an external chip in its own TO-100 package. [ 2 ]
Designers predominantly used MOSFET transistors with pMOS logic in the early 1970s, switching to nMOS logic after the mid-1970s. nMOS had the advantage that it could run on a single voltage, typically +5V, which simplified the power supply requirements and allowed it to be easily interfaced with the wide variety of +5V transistor-transistor ...