CISC stands for Complex Instruction Set Computer. It comprises a complex instruction set. It incorporates a variable-length instruction format. Instructions that require register operands can take only two bytes.The instructions that require two memory addresses can take five bytes to include the complete instruction code. Thus, CISC has a variable-length encoding of instructions and the execution of instructions may take a varying number of clock cycles. The CISC processor provides direct manipulation of operands that are in memory.The task of a compiler is to generate a sequence of machine instructions for each high-level language statement. The task is simplified if ... Read More

Program interrupt defines the transfer of program control from a currently running program to another service program as a result of an external or internal created request. Control returns to the initial program after the service program is implemented.There are three major types of program interrupts that are as follows −External InterruptsExternal interrupts come from input-output (l/0) devices, from a timing device, from a circuit monitoring the power supply, or from any other external source. The timeout interrupt can result from a program that is in an endless loop and thus exceeded its time allocation. Power failure interrupt can have ... Read More

There are various characteristics of CMOS which are as follows −Noise Margin − The noise margin of CMOS logic ICs is significantly greater than that of TTL ICs. These circuits are available with a broad supply voltage range and the noise margin improves with the supply of voltage VCC.The noise margin of CMOS is roughly 0.45 VDD. If the operating voltage is 12 V, the noise margin will be 5.4V. This implies that the connecting link between the driver and the load will not be affected by the noise interference unless the peak value of the noise picked up exceeds ... Read More

The priority encoder is a circuit that executes the priority function. The logic of the priority encoder is such that two or more inputs appear at an equal time, the input having the largest priority will take precedence. The truth table of a four-input priority encoder is given in the table. The X’s in the table designate don’t care conditions. Input I0 has the largest priority, so indifferent of the values of other inputs when this is input is 1, the output creates an output xy=00.I1 has the next priority level. The output is 01 if I1=1 supported that I0=0, ... Read More

Wormhole routing is a unique case of virtual cut-through, where the buffers at the intermediate nodes are the size of a flit. The network latency is equal to in virtual cut-through and thus autonomous of the communication distance.The advantage of wormhole routing over circuit switching and virtual cut-through appears in networks where contention is not negligible. In circuit switching, once a channel is assigned to a message, it cannot be used by other messages until the channels become free. In virtual cut-through, blocked messages should be saved in the buffer of intermediate nodes.In wormhole routing, channels can be transferred by ... Read More

There are two basic problems to be solved in any scalable computer systems such as −Tolerate and hide the latency of remote loads.Tolerate and hide idling because of synchronization between parallel processors.Remote loads are unavoidable in scalable parallel systems that use some form of distributed memory. Accessing a local memory usually requires only one clock cycle while access to a remote memory cell can take two orders of magnitude longer time. If a processor issuing a remote load operation had to wait for the operation to be completed without doing any usual work in the meantime, the remote load would ... Read More

Process scheduling is the activity of the process manager that manages the elimination of the running procedure from the CPU and the selection of another procedure based on a particular approach. The objective of the process scheduling system is to maintain the CPU busy all the time and to produce minimum response time for all programs. For reaching this, the scheduler should use specific rules for swapping processes IN and OUT of the CPU.Process scheduling involves three key concepts such as the declaration of distinct process states, the specification of the state transition diagram, and the statement of a scheduling ... Read More

USB represents Universal Serial Bus. It is an industry-standard developed in the mid-1990s that represents the cables, connectors, and communication protocols used in a bus for connection, communication, and power supply among computer and electronic devices.USB operates at 12 Mbps with particular consideration for low-cost peripherals. It provides up to 127 devices with both synchronous and asynchronous data transfers. A USB cable has a rectangular “TYPE A” plug at the computer end and a square “TYPE B” plug at the peripheral end.A Universal Serial Bus (USB) is a common interface that allows the connection between devices and host controllers including ... Read More

RS-232 is a standard communication protocol for connecting computers and their peripheral devices to enable serial data exchange. In simple terms, RS232 represents the voltage for the path used for data exchange between the devices. It determines the common voltage and signal level, common pin wire configuration and minimum, amount of control signals.RS232 represents the signals connecting between DTE and DCE. Therefore, DTE represents Data Terminal Equipment and an example for DTE is a computer. DCE represents Data Communication Equipment or Data Circuit Terminating Equipment and an example for DCE is a modem.RS232 was introduced in the 1960s and was ... Read More

UART represents Universal Asynchronous Receiver Transmitter. It is dedicated to hardware related to serial communication. UART is one of the most generally used serial communication techniques. UART is being used in several applications like GPS Receivers, Bluetooth Modules, GSM and GPRS Modems, Wireless Communication Systems, RFID-based applications, etc.Functions of the UARTThere are various functions of UART which are as follows −It can change parallel data into serial data for outbound communicationsIt can change serial data into parallel data for inbound communicationsIt can add a parity checking bit on outbound transmissions and tests the parity bit for inbound transmissionsIt can handle ... Read More