For waveforms, see solution to Problem 4. Note: See Problem 4. The sign bit is not included in the model, but hand calculation shows that the 9th bit is 1, indicating that the result of the operation is negative. The truth table describes a combinational circuit. The state table describes a sequential circuit. The characteristic table describes the operation of a flip-flop. The excitation table gives the values of flip-flop inputs for a given state transition.
The four equations correspond to the algebraic expression of the four tables. The output is 0 for all 0 inputs until the first 1 occurs, at which time the output is 1. Thereafter, the output is the complement of the input.
The state diagram has two states. The statements associated with an initial keyword execute once, in sequence, with the activity expiring after the last statment competes execution; the statements assocated with the always keyword execute repeatedly, subject to timing control e.
Note: The expression substitution implied by the sequential ordering with the blocking assignment operator results. To retain E, it is necessary to declare E to be an output port of the module. Note: The statements must be written in an order than produces the effect of concurrent assignments.
Signal transitions that are caused by input signals that change on the active edge of the clock race with the clock itself to reach the affected flip-flops, and the outcome is indeterminate unpredictable. Conversely, changes caused by inputs that are synchronized to the inactive edge of the clock reach stability before the active edge, with predictable outputs of the flip-flops that are affected by the inputs.
Note: See Problem 5. Alternative: structural model. If the input to A0 is changed to 0 the counter counts incorrectly. It resumes a correct counting sequence when T is changed back to 1. The structure shown below gates the clock through a nand gate. In practice, the circuit can exhibit two problems if the load signal is asynchronous: 1 the gated clock arrives in the setup interval of the clock of the flip-flop, causing metastability, and 2 the load signal truncates the width of the clock pulse.
Additionally, the propagation delay through the nand gate might compromise the synchronicity of the overall circuit. Connect to the clock input of each flip-flop. Load Clock. Serial data is transferred one bit at a time.
A shift register can convert serial data into parallel data by first shifting one bit a time into the register and then taking the parallel data from the register outputs.
A shift register with parallel load can convert parallel data to a serial format by first loading the data in parallel and then shifting the bits one at a time.
Connect two ICs to form an 8-bit register. See solution to Problem 5. Q is set on the first 1 from x. The worst case is when all 10 flip-flops are complemented.
With E denoting the count enable in Fig. Use a 3-bit counter and a flip-flop initially at 0. A start signal sets the flip-flop, which in turn enables the counter.
On the count of 7 binary reset the flip-flop to 0 to disable the count with the value of 00 0. The clock generator has a period of Use a 2-bit counter to count four pulses. The 8 unused states and their next states are shown below: Next state. The valid states are the same as in a. The unused states have the following sequences: 2o 9o 4o 8 and 10o 13o 6o11o 5o 0.
The final states, 0 and 8, are valid. Note: This version of the solution situates the data shift registers in the test bench. The magnitude of the result is also shown. Because A is a register variable, it retains whatever value has been assigned to it until a new value is assigned.
Alternative: a behavioral model for synthesis is given below. The behavioral description implies the need for a mux at the input to a D-type flip-flop. Mem[45]; endmodule. Correct data: ROM would have 4 inputs and 6 outputs.
A 4 x 8 ROM would waste two outputs. From Fig. After the transfer, R2 holds the contents that were in R1 before the clock edge, and R2 holds its previous value incremented by 1. The operations specified in a flowchart are executed sequentially, one at a time. Thus, the operations listed within a state box, the operations specified by a conditional box, and the transfer to the next state in each ASM block are executed at the same clock edge. For example, in Fig. Note: To avoid counting a person more than once, the machine waits until x or y is deasserted before incrementing or decrementing the counter.
The machine also accounts for persons entering and leaving simultaneously. Block diagram and ASMD chart:. Note: Division by 2 of a negative number represented in bit 2s complement format Note: Multiplication by 2 of a positive number represented in bit 2s complement format.
AR; always M0. BR if M0. BR; always M0. CR if M0. Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Fatima Bashir. A short summary of this paper. Decimal, Binary, Octal and Hexadecimal Numbers from 16 10 to 31 10 Dec 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Bin 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Oct 20 21 22 23 24 25 26 27 30 31 32 33 34 35 36 37 Hex 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F Decimal Binary Octal Hexadecimal A C 16 b E7C.
Using K-maps: a s. All simulations performed using Xilinx Foundation Series software.
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