Register Transfer Language Quiz

Which of the following statements about Register Transfer Language (RTL) is correct? Assume a system where registers R1, R2, and R3 are connected to a shared bus with control signals. If the operation R1←R2+R3 is performed in one clock cycle, what must the control logic ensure to avoid bus conflicts?

• Ensure R2 and R3 do not output simultaneously to the bus.

• Enable the output of both R2 and R3 to the bus at the same time.

• Trigger write control for R1 and read control for R2 and R3 simultaneously.

• Set the bus in read-only mode during the transfer operation.

Consider a digital system with four registers R1, R2, R3, and R4, and a control unit with micro-operations such as R1←R2+R3. How does the RTL notation ensure modularity in designing micro-operations for sequential circuits?

• By abstracting the hardware-level implementation details into higher-level operations.

• By specifying direct wiring between registers for each operation.

• By prioritizing register assignments based on clock cycles.

• By restricting the transfer of data between registers to predefined sequences.

In a system with a 4-bit register R1 and a 4-bit register R2, the transfer operation R1←R2+1 involves addition and storage. What is the primary condition to ensure this operation executes correctly in a clock cycle?

• R2 must output its value to a shared ALU.

• R1 and R2 must share the same memory location.

• The carry bit from R2+1 must be stored in an additional register.

• R1 and R2 must perform the transfer simultaneously.

What would be the effect of performing a register transfer R1←R1+2 using an arithmetic logic unit (ALU) that supports only basic addition and shift operations?

• R1 is incremented by 2 using two sequential clock cycles.

• The ALU uses a shift operation to simulate the increment by 2.

• The operation fails because basic addition cannot handle increments beyond 1.

• The ALU requires an additional intermediate register to store partial results.

A bus system connects four registers R1, R2, R3, and R4 to memory. Each register is 8 bits wide, and memory transfers occur using multiplexers. If R1←M[1001] is initiated, what does the control unit configure?

• Memory address lines point to 1001, and the output enable of memory is activated.

• R1 writes its value to memory location 1001.

• Memory simultaneously outputs its value to all registers.

• Data from R1 and R2 is merged and written to memory.

In a memory transfer operation M[ADDR]←R1, where ADDR is a 16-bit address, how does the control unit handle the address-to-memory decoding process?

• It uses a priority encoder to select the appropriate memory block.

• It uses a decoder circuit to activate the memory location specified by ADDR.

• It performs sequential read and write operations to locate the memory address.

• It uses a multiplexer to merge address bits into a unified data stream.

An arithmetic micro-operation performs R3←R1+R2. If the ALU requires 2 clock cycles for addition and data transfer is done in 1 cycle, what is the minimum time required to complete this operation?

• 1 cycle

• 2 cycles

• 3 cycles

• 4 cycles

How can subtraction R3←R1−R2 be implemented using only addition and 2's complement?

• By inverting all bits of R2 and adding 1 before performing addition.

• By directly adding the 1's complement of R2 to R1.

• By shifting R2 and R1 right before addition.

• By reversing the bit order of R1 and adding R2.

A logic micro-operation performs bitwise XOR on two registers R1 and R2. If R1=1101 and R2=1010, what is the value of R3←R1⊕R2?

• 0111

• 1111

• 1010

• 0000

What distinguishes logical AND from arithmetic AND in micro-operations?

• Logical AND operates on individual bits, while arithmetic AND operates on byte streams.

• Logical AND results are independent of carry bits, while arithmetic AND considers them.

• Logical AND is reversible, while arithmetic AND is not.

• Logical AND works only on signed numbers, while arithmetic AND works on both signed and unsigned.