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22-458: NMOS (or nMOS ) can refer to: NMOS logic n-channel MOSFET Networked Media Open Specifications (NMOS) an industry standard from Advanced Media Workflow Association for managing media streams Necessary military occupational specialty, see United States military occupation code Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

44-433: A burst mode for the caches, where four longwords can be loaded into the cache in a single operation. The MMU was mostly compatible with the external 68851 that would be used with the 68020, but being internal allowed it to access memory one cycle faster than a 68020/68851 combo. The 68030 did not include a built-in floating-point unit (FPU), and was generally used with the 68881 and the faster 68882 . The addition of

66-550: A p-type transistor body. This inversion layer, called the n-channel, can conduct electrons between n-type source and drain terminals. The n-channel is created by applying voltage to the third terminal, called the gate . Like other MOSFETs, nMOS transistors have four modes of operation: cut-off (or subthreshold), triode, saturation (sometimes called active), and velocity saturation. NMOS AND-by-default logic can produce unusual glitches or buggy behavior in NMOS components, such as

88-618: A passive component such as a memory chip, and some chips such as the Motorola 68030 were hybrids with both NMOS and CMOS sections. CMOS has been near-universal in integrated circuits since the 1990s. Additionally, just like in diode–transistor logic , transistor–transistor logic , emitter-coupled logic etc., the asymmetric input logic levels make NMOS and PMOS circuits more susceptible to noise than CMOS. These disadvantages are why CMOS logic has supplanted most of these types in most high-speed digital circuits such as microprocessors despite

110-404: A resistor, so the whole circuit can be made with n-channel MOSFETs only. NMOS circuits are slow to transition from low to high. When transitioning from high to low, the transistors provide low resistance, and the capacitive charge at the output drains away very quickly (similar to discharging a capacitor through a very low resistor). But the resistance between the output and the positive supply rail

132-443: A technology first developed by Federico Faggin at Fairchild Semiconductor . These silicon gates are still used in most types of MOSFET based integrated circuits , although metal gates ( Al or Cu ) started to reappear in the early 2000s for certain types of high speed circuits, such as high performance microprocessors. The MOSFETs are n-type enhancement mode transistors, arranged in a so-called "pull-down network" (PDN) between

154-429: A very low resistance between the output and the negative supply, forcing the output to be low (logic 0, = False). When both A and B are high, both transistors are conductive, creating an even lower resistance path to ground. The only case where the output is high is when both transistors are off, which occurs only when both A and B are low, thus satisfying the truth table of a NOR gate: A MOSFET can be made to operate as

176-473: Is zero (or false ), the PDN will be active, meaning that at least one transistor is allowing a current path between the negative supply and the output. This causes a voltage drop over the load, and thus a low voltage at the output, representing the zero. As an example, here is a NOR gate implemented in schematic NMOS. If either input A or input B is high (logic 1, = True), the respective MOS transistor acts as

198-442: Is a 32-bit microprocessor in the Motorola 68000 family . It was released in 1987. The 68030 was the successor to the Motorola 68020 , and was followed by the Motorola 68040 . In keeping with general Motorola naming, this CPU is often referred to as the 030 (pronounced oh-three-oh or oh-thirty ). The 68030 is essentially a 68020 with a memory management unit (MMU) and instruction and data caches of 256 bytes each. It added

220-509: Is much greater, so the low to high transition takes longer (similar to charging a capacitor through a high value resistor). Using a resistor of lower value will speed up the process but also increases static power dissipation. However, a better (and the most common) way to make the gates faster is to use depletion-mode transistors instead of enhancement-mode transistors as loads. This is called depletion-load NMOS logic . Motorola 68030 The Motorola 68030 (" sixty-eight-oh-thirty ")

242-459: The 6502 "illegal opcodes" which are absent in CMOS 6502s. In some cases such as Commodore's VIC-II chip, the bugs present in the chip's logic were extensively exploited by programmers for graphics effects. For many years, NMOS circuits were much faster than comparable PMOS and CMOS circuits, which had to use much slower p-channel transistors. It was also easier to manufacture NMOS than CMOS, as

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264-681: The Sun Microsystems Sun-3x line of desktop workstations (the earlier "sun3" used a 68020), Apollo Computer 's DN3500 and DN4500 workstations, laser printers and the Nortel Networks DMS-100 telephone central office switch. More recently , the 68030 core has also been adapted by Freescale into a microcontroller for embedded applications. LeCroy has used the 68EC030 in certain models of their 9300 Series digital oscilloscopes including “C” suffix models and high performance 9300 Series models, along with

286-562: The 1970s. CMOS circuits for contrast generate almost no heat unless the transistor count approaches 1 million. CMOS components were relatively uncommon in the 1970s-early 1980s and would typically be indicated with a "C" in the part number. Throughout the 1980s, both NMOS and CMOS parts were widely used with CMOS becoming more widespread as the decade went along. NMOS was preferred for components that performed active processing such as CPUs or graphics processors due to its higher speed and cheaper manufacturing cost as these were expensive compared to

308-621: The FPU was a major design note of the subsequent 68040. The 68030 lacks some of the 68020's instructions, but it increases performance by ≈5% while reducing power draw by ≈25%. The 68030 features 273,000 transistors. A lower-cost version was also released, the Motorola 68EC030, lacking the on-chip MMU. It was commonly available in both 132-pin QFP and 128-pin PGA packages. The poorer thermal characteristics of

330-577: The Mega Waveform Processing hardware option for 68020-based 9300 Series models. The 68EC030 is a low cost version of the 68030, the difference between the two being that the 68EC030 omits the on-chip memory management unit (MMU) and is thus essentially an upgraded 68020. The 68EC030 was used as the CPU for the low-cost model of the Amiga 4000 , and on a number of CPU accelerator cards for

352-609: The QFP package limited that variant to 33 MHz; the PGA 68030s included 40 MHz and 50 MHz versions. There was also a small supply of QFP packaged EC variants. The 68030 can be used with the 68020 bus, in which case its performance is similar to 68020 that it was derived from. However, the 68030 provides an additional synchronous bus interface which, if used, accelerates memory accesses up to 33% compared to an equally clocked 68020. The finer manufacturing process allowed Motorola to scale

374-419: The circuit is not switching, leading to high power consumption. Another disadvantage of NMOS circuits is their thermal output. Due to the need to keep constant voltage running through the circuit to hold the transistors' states, NMOS circuits can generate a considerable amount of heat in operation which can reduce the device's reliability. This was especially problematic with the early large gate process nodes in

396-399: The fact that CMOS was originally very slow compared to logic gates built with bipolar transistors . MOS stands for metal-oxide-semiconductor , reflecting the way MOS-transistors were originally constructed, predominantly before the 1970s, with gates of metal, typically aluminium. Since around 1970, however, most MOS circuits have used self-aligned gates made of polycrystalline silicon ,

418-693: The full-version processor to 50 MHz. The EC variety topped out at 40 MHz. The 68030 was used in many models of the Apple Macintosh II and Commodore Amiga series of personal computers , NeXT Cube , later Alpha Microsystems multiuser systems, and some descendants of the Atari ST line such as the Atari TT and the Atari Falcon . It was also used in Unix workstations such as

440-443: The latter has to implement p-channel transistors in special n-wells on the p-substrate, not prone to damage from bus conflicts, and not as vulnerable to electrostatic discharge damage. The major drawback with NMOS (and most other logic families ) is that a direct current must flow through a logic gate even when the output is in a steady state (low in the case of NMOS). This means static power dissipation , i.e. power drain even when

462-442: The logic gate output and negative supply voltage (typically the ground). A pull up (i.e. a "load" that can be thought of as a resistor, see below) is placed between the positive supply voltage and each logic gate output. Any logic gate , including the logical inverter , can then be implemented by designing a network of parallel and/or series circuits, such that if the desired output for a certain combination of boolean input values

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484-498: The title NMOS . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=NMOS&oldid=1228643213 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages NMOS logic NMOS transistors operate by creating an inversion layer in

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