Combinational circuit?
A combination circuit is a connected arrangement of logic gates with a set of input and output. At any the binary value of the output are a function of the binary input...In the following diagram n is the input variable and m is the output variable...It can also show the relationship between the input and output variables.
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Half adder: The most basic digital arithmetic circuit is the addition of two binary bit. A combination circuit that perform this calculation is called a half adder. The input variable in a half adder are called the auged and addend bits..The output variable are sum and carry. It is necessary to specify two output variable because the sum of 1+1 is binary 10 which has two digit.
Output of sum= x'y+xy'
c=x.y
Output of sum= x'y+xy'
c=x.y
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FULL ADDER: Full adder is a digital arithmetic circuit which is used to add 3 binary bits. In other words we can define a full adder is the combination of two half adder....As it takes three it only generate two output sum and carry..
output of sum= a (ex-or) b (ex-or) c
carry=AB+BC+AC
output of sum= a (ex-or) b (ex-or) c
carry=AB+BC+AC
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HALF SUBTRACTOR: The half-subtractor is a combinational circuit which is used to perform subtraction of two bits. It has two inputs, X (minuend) and Y (subtrahend) and two outputs D (difference) and B (borrow).The circuit of the half substractor is shown in figure...
output of difference: x'y+xy'
borrow: x.y'
output of difference: x'y+xy'
borrow: x.y'
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Full subtractor: As in the case of the addition using logic gates, a full subtractor is made by combining two half-subtractors and an additional OR-gate. A full subtractor has the borrow in capability and so allows cascading which results in the possibility of multi bit subtraction.
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SEQUENTIAL CIRCUIT.,..
In digital circuit theory, sequential logic is a type of logic circuit whose output depends not only on the present input but also on the previous output. Sequential logic has storage in the form of Flip-Flop(memory) while combinational logic does not....Sequential circuits are important because only combinational logic is not enough for digital system. A combinational logic just takes the inputs and gives the outputs . By adding a sequential logic to it, one can break down the various functions of the system in to a sequence of operations and implement them at only the time at which they are required.
SR : An SR Flip-Flop can be considered as a basic one-bit memory device that has two inputs, one which will "SET" the device and another which will "RESET" the device back to its original state and an output Q that will be either at a logic level "1" or logic "0" depending upon this Set/Reset condition. The simplest way to make any basic one-bit Set/Reset SR flip-flop is to connect together a pair of cross-coupled 2-input NAND Gates to form a Set-Reset......... If the input R is at logic level "0" (R = 0) and input S is at logic level "1" (S = 1), the NAND Gate Y has at least one of its inputs at logic "0" therefore, its output Q must be at a logic level "1"
SR : An SR Flip-Flop can be considered as a basic one-bit memory device that has two inputs, one which will "SET" the device and another which will "RESET" the device back to its original state and an output Q that will be either at a logic level "1" or logic "0" depending upon this Set/Reset condition. The simplest way to make any basic one-bit Set/Reset SR flip-flop is to connect together a pair of cross-coupled 2-input NAND Gates to form a Set-Reset......... If the input R is at logic level "0" (R = 0) and input S is at logic level "1" (S = 1), the NAND Gate Y has at least one of its inputs at logic "0" therefore, its output Q must be at a logic level "1"
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D type: the d type flipflop is slight modification of sr flipflop. A SR flipflop is converted to D type by inserting an inverter between s and r and assigning the symbol D to the input..The D input is sampled during the occurrence of the clock transition from 0 to 1.. If D=0, the output of the flip flop goes to 0 state....
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JK: JK flipflop is a refinement of the SR flip flop in that the indeterminate condition of the SR type is defined in the JK type..Input j & k behave like inputs S and r to set and clear the flip flop..If J and K are both low then no change occurs. If J and K are both high at the clock edge then the output will toggle from one state to the other. It can perform the functions of the set/reset flip-flop ........It has the following characteristics If both inputs are 0, then it remains in the same state as it was before the clock pulse occurred; again like the RS flip flop. Other is If both inputs are high, the clock pulse toggles the flip-flop.
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T : Another type of flip flop is the T type flip flop. This flip flop is obtained from JK type when the input J & K are connected to provide a single input Called T...The T type has only two condition. When T=0 a clock transition does not change the state of flip flop...When T=1 a clock transition compliments the state of the flipflop....
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Shift register........
A register is capable of shifting its binary information in one or both direction is called a shift register...The logical configuration of shift register consist of chain of flipflop, with the output of one flip flop connected to the input of the next flipflop..All flip flop receives common clock pulses that initiate the shift from one stage to next.. The simple type of shift register is one that uses only flipflop ....Following are the different modes of shift register
Serial-in to Parallel-out (the register is loaded with serial data, one bit at a time, with the stored data being available in parallel form.),
Serial-in to Serial-out : the data is shifted serially "IN" and "OUT" of the register, one bit at a time in either a left or right direction under clock control.
Parallel-in to Parallel-out: the parallel data is loaded into the register simultaneously and is shifted out of the register serially one bit at a time under clock control..
Parallel-in to Serial-out : the parallel data is loaded simultaneously into the register, and transferred together to their respective outputs by the same clock pulse.
The effect of data movement from left to right through a shift register can be presented graphically as:
Serial-in to Parallel-out (the register is loaded with serial data, one bit at a time, with the stored data being available in parallel form.),
Serial-in to Serial-out : the data is shifted serially "IN" and "OUT" of the register, one bit at a time in either a left or right direction under clock control.
Parallel-in to Parallel-out: the parallel data is loaded into the register simultaneously and is shifted out of the register serially one bit at a time under clock control..
Parallel-in to Serial-out : the parallel data is loaded simultaneously into the register, and transferred together to their respective outputs by the same clock pulse.
The effect of data movement from left to right through a shift register can be presented graphically as:
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RAM VS ROM.......
RAM and ROM are both different types of
memories used in any computer to make it fast and to enable it to access
information stored in the computer. Every computer comes with a certain
amount of physical memory which is actually chips that holds the data and instruction. This
memory is referred to as Random Access Memory or RAM. RAM is a part of
hardware that stores operating system’s
application programs and currently running processes that can be
accessed by the user ,. Data in RAM
stays for only as long as the computer is running, and gets deleted as
soon as computer is switched off. RAM usually comes in the form of
microchips of different sizes such as 256MB, 512MB, 1GB, 2GB etc. Computers are so designed that this RAM can be increased up to a certain capacity.
ROM, on the other hand refers to Read Only Memory. Every computer comes fitted with this memory that holds instructions for starting up the computer. This is a memory that has data written permanently on it and is not reusable. However, there are certain kinds of read only memory that can be rewritten but they are called Erasable Programmable Read Only Memory, or EPROM. These are generally in the form of CD-ROM or Floppy Disk that can load the OS to the RAM.
DIFFERENCE: 1.RAM is Random Access Memory. It is a volatile type of memory that needs electricity to flow to retain information. It is the type of memory that computers use to process programs.ROM is Read Only Memory. Essentially it is a piece of permanently written information stored as memory. There are versions of this memory that can be rewritten but it is then called EPROM (Erasable Programmable Read Only Memory) and generally takes ultraviolet light to clear.
2. Read only memory or ROM is slower when compared to RAM. That is why most personal computers have a greater capacity of ROM. In simple terms, Read only memory (ROM) is where software are developed...
3. Speed is the major difference between RAM and ROM because the application first has to be loaded via the ROM to run software and applications. This memory is what remains when shut down the computer, though ROM is updated when the PC is on.
ROM, on the other hand refers to Read Only Memory. Every computer comes fitted with this memory that holds instructions for starting up the computer. This is a memory that has data written permanently on it and is not reusable. However, there are certain kinds of read only memory that can be rewritten but they are called Erasable Programmable Read Only Memory, or EPROM. These are generally in the form of CD-ROM or Floppy Disk that can load the OS to the RAM.
DIFFERENCE: 1.RAM is Random Access Memory. It is a volatile type of memory that needs electricity to flow to retain information. It is the type of memory that computers use to process programs.ROM is Read Only Memory. Essentially it is a piece of permanently written information stored as memory. There are versions of this memory that can be rewritten but it is then called EPROM (Erasable Programmable Read Only Memory) and generally takes ultraviolet light to clear.
2. Read only memory or ROM is slower when compared to RAM. That is why most personal computers have a greater capacity of ROM. In simple terms, Read only memory (ROM) is where software are developed...
3. Speed is the major difference between RAM and ROM because the application first has to be loaded via the ROM to run software and applications. This memory is what remains when shut down the computer, though ROM is updated when the PC is on.
Encoder and Decoder....
Encoder: An encoder converts an active input signal into a coded output signal. In encoders, the number of output lines is less than the number of input lines. The internal logic within the encoder converts this active input to a coded binary output. In other words we can say that it takes 2 to the power n lines and display a output as n lines.....The diagram show the decoder it is also called as a 8 to 3 binary encoder/.....DRAW THE DIAGRAM and TRUTH TABLE of 8 to 3.......
DECODER: A Decoder is the exact opposite to that of an "Encoder". It is basically, a combinational type logic circuit that converts the binary code data at its input into one of a number of different output lines, Binary Decoders have inputs of 2-bit, 3-bit or 4-bit codes depending upon the number of data input lines, and a n-bit decoder has 2n output lines. The example decoder circuit would be an AND gate because the output of an AND gate is "High" (1) only when all its inputs are "High. If instead of AND gate, the NAND gate is connected the output will be "Low" (0) only when all its inputs are "High"........DRAW THE DIAGRAM and TRUTH TABLE 3 to 8.......
DECODER: A Decoder is the exact opposite to that of an "Encoder". It is basically, a combinational type logic circuit that converts the binary code data at its input into one of a number of different output lines, Binary Decoders have inputs of 2-bit, 3-bit or 4-bit codes depending upon the number of data input lines, and a n-bit decoder has 2n output lines. The example decoder circuit would be an AND gate because the output of an AND gate is "High" (1) only when all its inputs are "High. If instead of AND gate, the NAND gate is connected the output will be "Low" (0) only when all its inputs are "High"........DRAW THE DIAGRAM and TRUTH TABLE 3 to 8.......
Multiplexer and Demultiplexer....
Multiplexer: Multiplexer means many into one. A multiplexer is a combinational digital circuit in which output is directed from one of the various input or in other words which contains many input lines and only one output line. Multiplexers are used in building digital semiconductors such as CPUs and graphics controllers. In these applications, the number of inputs is generally a multiple of 2....Types of multiplexer are 2 to 1, 4 to 1, 8 to 1 and 16 to 1...The diagram below shows the 4 to 1 multiplexer...
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DEMULTI:
A De-multiplexer or a De-Mux is a digital combinational circuit used to distribute one input line over a multiple number of output lines.In other words we can say They are the exact opposite of the Multiplexers that they have one single input data line and then switch it to any one of their individual multiple output lines one at a time. The demultiplexer converts the serial data signal at the input to a parallel data at its output lines as shown below and also shows the 1 to 4 demux and its truth table....
A De-multiplexer or a De-Mux is a digital combinational circuit used to distribute one input line over a multiple number of output lines.In other words we can say They are the exact opposite of the Multiplexers that they have one single input data line and then switch it to any one of their individual multiple output lines one at a time. The demultiplexer converts the serial data signal at the input to a parallel data at its output lines as shown below and also shows the 1 to 4 demux and its truth table....
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Program control....
Instruction are always in a sequence memory location. When processed in cpu, the instruction are fetched from the memory location and are executed....Each time the instruction is fetched from the memory and the program is incremented so that it contain the address of next instruction in sequence.... After the execution of data transfer or data manipulation , control returns to the fetch cycle with the program counter containing the address of the instruction next in sequence....Program control instruction specifies the condition for altering the content of the program counter , while data transfer and manipulation instruction specifies the condition for data processing operation.......Some program control instruction are Branch,Call , Compare, Jump, Skip , Return , Test......Branch and jump instruction may be conditional and unconditional...The conditional specifies that condition is positive or zero...The skip instruction does not need an address field and it is called as a zero address instruction... The Compare instruction performs a subtraction between two operands......The test operation perform a logical AND of two operands and update status of bits without changing the operands....