Editing Clock signal (section)

=== 4-phase clock ===
{{see also|Four-phase logic}}
Some early integrated circuits use [[four-phase logic]], requiring a four-phase clock input consisting of four separate, non-overlapping clock signals.<ref>{{citation |url=http://micro.magnet.fsu.edu/primer/digitalimaging/concepts/fourphase.html |title=Concepts in digital imaging - Four Phase CCD Clocking |publisher=Micro.magnet.fsu.edu |access-date=2012-01-08}}</ref> This was particularly common among early microprocessors such as the [[National Semiconductor]] [[IMP-16]], [[Texas Instruments TMS9900]], and the [[Western Digital]] [[MCP-1600]] chipset used in the [[Digital Equipment Corporation|DEC]] [[PDP-11#LSI-11|LSI-11]].

Four phase clocks have only rarely been used in newer CMOS processors such as the DEC WRL MultiTitan microprocessor.<ref>
{{cite journal |author-link=Norman P. Jouppi |last1=Jouppi |first1=N.P. |last2=Tang |first2=J.F. |title=A 20-MIPS sustained 32-bit CMOS microprocessor with high ratio of sustained to peak performance |journal=IEEE Journal of Solid-State Circuits |volume=24 |issue=5 |pages=1348–59 |date=1989 |doi=10.1109/JSSC.1989.572612 |bibcode=1989IJSSC..24.1348J |url=}}
</ref> and in [[Intrinsity]]'s Fast14 technology. Most modern microprocessors and [[microcontroller]]s use a single-phase clock.