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CMOS inverter (a NOT logic gate). Complementary metal–oxide–semiconductor (CMOS, / ˈ s iː m ɒ s /, also US: /-ɔː s / [1]) is a type of metal–oxide–semiconductor field-effect transistor (MOSFET) fabrication process that uses complementary and symmetrical pairs of p-type and n-type MOSFETs for logic functions. [2]
Nonvolatile BIOS memory refers to a small memory on PC motherboards that is used to store BIOS settings. It is traditionally called CMOS RAM because it uses a volatile, low-power complementary metal–oxide–semiconductor (CMOS) SRAM (such as the Motorola MC146818 [1] or similar) powered by a small battery when system and standby power is off. [2]
The BIOS uses the boot devices set in Nonvolatile BIOS memory , or, in the earliest PCs, DIP switches. The BIOS checks each device in order to see if it is bootable by attempting to load the first sector (boot sector). If the sector cannot be read, the BIOS proceeds to the next device.
The BIOS typically sets up a real mode interrupt handler at this vector that provides video services. Such services include setting the video mode, character and string output, and graphics primitives (reading and writing pixels in graphics mode).
Generally, a TTL output does not rise high enough to be reliably recognized as a logic 1 by a CMOS input, especially if it is only connected to a high-input-impedance CMOS input that does not source significant current. This problem was solved by the invention of the 74HCT family of devices that uses CMOS technology but TTL input logic levels.
CMOS memory was commercialized by RCA, which launched a 288-bit CMOS SRAM memory chip in 1968. [23] CMOS memory was initially slower than NMOS memory, which was more widely used by computers in the 1970s. [24] In 1978, Hitachi introduced the twin-well CMOS process, with its HM6147 (4 kb SRAM) memory chip, manufactured with a 3 μm process. The ...
The purpose of overclocking is to increase the operating speed of a given component. [3] Normally, on modern systems, the target of overclocking is increasing the performance of a major chip or subsystem, such as the main processor or graphics controller, but other components, such as system memory or system buses (generally on the motherboard), are commonly involved.
The following is a list of CMOS 4000-series digital logic integrated circuits.In 1968, the original 4000-series was introduced by RCA.Although more recent parts are considerably faster, the 4000 devices operate over a wide power supply range (3V to 18V recommended range for "B" series) and are well suited to unregulated battery powered applications and interfacing with sensitive analogue ...