10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 1/14 ELEC1601_ELEC9601 End of Sem (practice) Started: Oct 30 at 14:27 Quiz Instructions 1 ptsQuestion 1 A machine code must support arithmetic instructions of the following format: opcode, destination register, source register. e.g. SUB, R0, R1 translates to perform the subtract R0 – R1 and store the result in R0 The total number of different arithmetic instructions that must be supported is 183, with 2^4 different registers. All bits for this instruction are utilised in the encoding. What is the minimum number of bits required for this machine code 1 ptsQuestion 2 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 2/14 Suppose you have a circuit that implements the following truth table: x y z Out 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 Suppose you then create two instances of this circuit and wire them up as follows (the second instance has its final input inverted): What is the output of the circuit if a=1, b=1, c=1 1 ptsQuestion 3 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 3/14 Study the following circuit and timing diagram (consisting of D- type latches, D-type Flip-Flops and Logic Gates): What is the value for Out at the highlighted times (if it cannot be determined, write UNKNOWN) (highlighted red) = [ Select ] (highlighted yellow) = [ Select ] 1 ptsQuestion 4 Study the following Finite State Machine: 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 4/14 p 0 words First create a truth table showing how to compute the next state from the current state 1 ptsQuestion 5 Edit View Insert Format Tools Table 20px Paragraph 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 5/14 Assume that a memory is initialised as follows: Memory Address Cell Contents 0xC336 0x11 0xC337 0x00 0xC338 0x11 0xC339 0x11 0xC33A 0x11 0xC33B 0x00 Suppose the X register is initialised to 0xC338 and the following commands are issued: LD R1, X+ LD R2, X+ What is the value in R26 (Write your answer in decimal, 0 for unknown) 1 ptsQuestion 6 Assume that a memory is initialised as follows: Memory Address Cell Contents 0x00C336 0x25 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 6/14 0x00C337 0x65 0x00C338 0x60 0x00C339 0x67 0x00C33A 0x72 0x00C33B 0x44 A computer system has the value 0x00C338 in its stack pointer. The stack grows (when you push data) towards lower memory positions. Suppose the system executes the sequence of instructions: POP R1 POP R2 ADD R1 R2 MOV R2 R1 ADD R2 R2 PUSH R1 PUSH R2 PUSH R3 What value is in R3. (Write your answer in decimal. If it cannot be computed given the above information, enter the value 0) 1 ptsQuestion 7 Suppose the following two instructions are executed: ANDI R20, 5 BREQ Destination 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 7/14 The machine code for the BREQ instruction is as follows: 1111 0000 0011 1001 Assume the following register values: Program counter = 0x001 R20 = 0x07 What is the new value of the PC The relevant information for the instruction set is given below: 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 8/14 1 ptsQuestion 8 Study the following code (you can assume “. . .” refers to code that is not shown) main: … LDI R27, hi8(d1) ; PC = 0x0A35, SP = 0x0B17 LDI R26, lo8(d1) LD R18, X+ ADD R18, R18 PUSH R18 CALL subroutine1 … 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 9/14 subroutine1: POP R18 ; What is the value of the SP at this line of code … MOV R24, R7 ; result RET You can assume that the address of subroutine1 is 0x1A19. What is the value of the Stack Pointer at the highlighted line of code (Write your answer in Decimal) 1 ptsQuestion 9 Consider the following definitions for d1, which represents a 4 byte array of integer values: d1: .byte 0, 1, 2, 3 (1st element of the array for d1 has the value 0, 2nd element of the array for d1 has the value 1, 4th element of the array has the value 3) If d1 is located in address 0x0637, what is the value of the second element of d1 after executing the following instructions (Write your answer in Decimal) LDI R27, hi8(d1) LDI R26, lo8(d1) LDI R19, hi8(d1) LDI R18, lo8(d1) ST X+, R18 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 10/14 ADD R19 R18 ST -X, R19 1 ptsQuestion 10 An AVR assembly program defines the following variables and labels: .section .data D1: .byte 4, 4, 4, 10 D2: .byte 7, 8 If the address of D1 is 0x109, what is the address of D2 (Write your answer in Decimal) 1 ptsQuestion 11 What is the decimal value (base 10) held in R9 after the following sequence of instructions LDI R18, 0x219 MOV R9, R18 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 11/14 ADD R9, R9 1 ptsQuestion 12 Study the following program It was generated by the compiler avr-gcc that uses the AVR libc library, so obeys the convention for register management LDI R18, 5 PUSH R18 PUSH R10 CALL subroutine1; Call the subroutine POP R2 POP R2 ADD R10 R2 ADD R10 R3 ADD R10 R18 … subroutine1: … ADD R18 R10; Values for the registers after completion of th is line of code are shown in the text below PUSH R0; RET; Suppose at the start of the subroutine, R18 = 2, R10 = 8; Suppose at the end of the subroutine after completion of the line highlighted in Red: R0=4, R2=9, R18=8 What is the value stored in R10 after completion of the line highlighted in Green Write 0 if unknown. Write your answer in Decimal 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 12/14 1 ptsQuestion 13 Study the following program It was generated by the compiler avr-gcc that uses the AVR libc library, so obeys the convention for register management LDI R20, 3 LDI R21, 7 LDI R22, 7 LDI R23, 7 LDI R24, 4 PUSH R20 PUSH R21 PUSH R22 PUSH R23 PUSH R24 CALL subroutine1; Call the subroutine … subroutine1: IN R31, 0x3E ; Z <- SP IN R30, 0x3D LDD R18, Z+4 SUB R18, R19 ; What is the value for R18 after execution of this line is complete ... Reminder, the IN R31, 0x3E ; IN R30, 0x3D commands load the stack pointer into the Z register What is the value stored in R18 in subroutine 1 after completion of the highlighted SUB instruction. Write 0 if unknown. Write your answer in Decimal 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 13/14 1 ptsQuestion 14 Study the following handwritten (potentially buggy) code (you can assume “. . .” refers to code that is not shown main: … LDS R25, x PUSH R25, CALL subroutine1 ; This instruction is at location 0x1234 POP R0, … subroutine1: ; This subroutine is at location 0xAB99 … MOV R25, R8 PUSH R0 CALL subroutine2 POP R25 … MOV R24, R7 ; result RET subroutine2: ; This subroutine is at location 0xAD36. No code is missing from this subroutine POP R0 ADD R0 R0 PUSH R0 RET Assume the return address stored in the stack by the CALL instruction is 3 bytes. What is the value of the Program Counter after the RET instruction in Subroutine 2 (Write your answer in Decimal, write 0 if unknown) 10/30/22, 11:28 AM Quiz: ELEC1601_ELEC9601 End of Sem (practice) https://canvas.sydney.edu.au/courses/44479/quizzes/208463/take 14/14 Saved at 11:28 1 ptsQuestion 15 Suppose you have a computer system with a 4 stage pipeline and clock period of 193 ns. Assuming there are no pipeline stalls (no branching, no I/O requests, no interrupts etc.), how long would it take to execute the following instructions: ADD R1 R2 ADD R1 R3 SUB R1 R4 Registers R1 to R4 are initialised to 5, 8, 5 and 4 respectively. Your answer should be in ns. Submit Quiz
