Decoder

Decoder is a multiple input; multiple output logic circuit that converts coded inputs in coded outputs, where input and output codes are different.

Inputs have fewer inputs than output. Below is a simple example of 2-to-4 decoder.

Intel Unveils 32nm Chips

Intel on Thursday said it is in volume production of its next-generation 32-nanometer desktop and laptop chips, with products available for low-end, mainstream and high-end PCs.

A total of 17 new CPUs, along with three new chipsets and seven chips providing Wi-Fi and WiMax support, will be available in computer makers' products early next year, following the International Consumer Electronics Show in January, Intel executives said during a news conference in San Francisco. The new products will be in computers covering 400 separate designs.

All the new products are built using Intel's next-generation 32-nanometer technology, codenamed Westmere, and are based on the Nehalem microarchitecture. The brands are Core i3 for low-end systems, Core i5 for mainstream PCs and Core i7 for the highest end computers used in video editing and playing top-of-the line video games. Intel started shipping 32-nanometer processors this year, but the upcoming products are the first to cover all PC categories.

The Core i7 processors, codenamed Lynnfield for the desktop models and Clarksfield for the laptop versions, are all quad-core processors. The i5 processors are available in quad-core and dual-core models, and the i3 are only dual-core.

All of the dual-core processors have the CPU and graphics processor integrated on a single die, with the memory controller on a separate chip. Previous generations had each of the three components on a separate die. The Core i7 products, which are typically used in systems with a separate graphics card, do not have integrated graphics, which Intel now calls its HD (high-definition) Graphics. Previously, Intel called its graphics technology GMA for graphics media accelerator.

Intel says its latest graphics technology is better than the previous generation because more of the work is done on the hardware versus software. As a result, end users will see smoother, sharper and more colorful playback of Blu-ray video and DVDs. The same is true for picture-in-picture playback, according to Intel.

In addition, Intel graphics support multiple monitors and DisplayPort and Dual HDMI interfaces. The former is used to connect to monitors and home-theater systems and the latter to audio/video devices, such as Blu-ray disc players, set-top boxes and video-game consoles.

The Core i5 and i7 products will all have Intel's Turbo-Boost technology, which ratchets up processing power to meet workload bursts and then lowers it when extra horsepower is no longer needed. The technology also has what Intel calls "power-gating," which will leave idle all cores that aren't needed to accomplish particular tasks. Turbo-Boost technology in general makes processors more efficient in terms of energy use.

Intel plans to release pricing and further details on the new products at CES, which runs from Jan. 7-10 in Las Vegas, Nev.

Intel unveiled its new line the same day researcher IDC released an upbeat report on the PC market. The analyst firm said the overall market in terms of shipments returned to year-over-year growth in the third quarter after three consecutive quarters of decline. Starting next year, IDC says shipments will increase in the low double-digits through 2013.

While facing a brighter outlook for the PC industry, Intel is looking at dark clouds on the legal front. The chipmaker is dealing with increasing pressure from government agencies in and outside the U.S. that accuse the company of anti-competitive behavior. Intel's latest legal headache came this week from the Federal Trade Commission, which used the company, claiming it uses its dominance to stifle competition.

Sequential Circuits

Sequential logic differs from combinational logic in that the output of the logic device is dependent not only on the present inputs to the device, but also on past inputs; i.e., the output of a sequential logic device depends on its present internal state and the present inputs. This implies that a sequential logic device has some kind of memory of at least part of its ``history'' (i.e., its previous inputs). Below figure shows a generic structure for sequential circuit.

The memory elements are devices capable of storing binary info. The binary info stored in the memory elements at any given time defines the state of the sequential circuit. The input and the present state of the memory element determines the output. Memory elements next state is also a function of external inputs and present state. A sequential circuit is specified by a time sequence of inputs, outputs, and internal states.

There are two types of sequential circuits. Their classification depends on the timing of their signals: Synchronous sequential circuits Asynchronous sequential circuits Asynchronous sequential circuits: This is a system whose outputs depend upon the order in which its input variables change and can be affected at any instant of time. Gate-type asynchronous systems are basically combinational circuits with feedback paths. Because of the feedback among logic gates, the system may, at times, become unstable. Consequently they are not often used. Below is an example circuit.

Synchronous sequential circuits:This type of system uses storage elements called flip-flops that are employed to change their binary value only at discrete instants of time. Synchronous sequential circuits use logic gates and flip-flop storage devices. Sequential circuits have a clock signal as one of their inputs. All state transitions in such circuits occur only when the clock value is either 0 or 1 or happen at the rising or falling edges of the clock depending on the type of memory elements used in the circuit. Synchronization is achieved by a timing device called a clock pulse generator. Clock pulses are distributed throughout the system in such a way that the flip-flops are affected only with the arrival of the synchronization pulse. Synchronous sequential circuits that use clock pulses in the inputs are called clocked-sequential circuits. They are stable and their timing can easily be broken down into independent discrete steps, each of which is considered separately.

Below figure shows example circuit:

A clock signal is a periodic square wave that indefinitely switches from 0 to 1 and from 1 to 0 at fixed intervals. Clock cycle time or clock period: the time interval between two consecutive rising or falling edges of the clock.