COMPSCI210 Computer Systems 1 SECOND SEMESTER, 2019
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COMPSCI210
SECOND SEMESTER, 2019
TEST
Computer Systems 1
Question 1
[1.5 marks] Convert 12.C16 to a decimal value.
(a) 12.87510
(b) 18.62510
(c) 18.7510
(d) 12.62510
(e) 12.510
Question 2
[1.5 marks] What is the decimal value of 1001012 which is a 6-bit two’s complement representation?
(a) -2710
(b) 3510
(c) 2710
(d) -3310
(e) -4510
Question 3
[1.5 marks] Which of the following logic expressions give result 0 and 1 respectively?
(a) 0 + (1 × 1) and 1 × (0 ⊕ 1)
(b) 0 + (1 × 1) and 1 × (1 ⊕ 1)
(c) 0 + (0 × 1) and 0 × (0 ⊕ 1)
(d) 0 + (0 × 1) and 1 × (1 ⊕ 1)
(e) 0 + (0 × 1) and 1 × (0 ⊕ 1)
Question 4
[1.5 marks] Based on the lock state diagram, what is the next state if the current state is D and R-13 is executed?
(a) B
(b) D
(c) A
(d) C
(e) None of the above
Question 5
[1.5 marks] What is the ASCII character with the value ‘C’ + 4?
(a) ‘F’
(b) ‘g’
(c) ‘f’
(d) ‘h’
(e) ‘G’
Question 6
[1.5 marks] Given that the inputs (I and S) and the outputs (Y) of the 8-to-1 multiplexer are I(7:0), S(2:0) and Y respectively. What should be Y if S is 1012?
(a) I(5)
(b) I(6)
(c) I(4)
(d) I(1)
(e) I(7)
Question 7
[1.5 marks] What is the binary representation for -1.510 using the IEEE 754 floating point format?"
(a) 1 01111111 110000000000000000000002
(b) 1 10000000 100000000000000000000002
(c) 1 10000000 111000000000000000000002
(d) 1 01111111 100000000000000000000002
(e) 1 01111111 111000000000000000000002
Question 8
[1.5 marks] According to the below memory architecture, which cell should be selected if the address is “10012”?
(a) Cell 8
(b) Cell 9
(c) Cell 10
(d) Cell 6
(e) Cell 13
Question 9
[1.5 marks] Which one is the characteristic of register compared to memory?
(a) Can be accessed simultaneously
(b) Slower
(c) Read-only
(d) Smaller area per data-bit
(e) One address can be accessed at a time
Question 10
[1.5 marks] What is the meaning of the directive ".ORIG"?
(a) Allocate a few initialized characters and a null terminator for that label
(b) Allocate a word of storage for that label with an initialized value
(c) Define the starting address of the program
(d) Allocate a few words of storage for that label (e) Indicate that it is the end of the program
Question 11
[1.5 marks] What is the meaning of the following LC3 instruction?
STI R2, -4
(a) Mem[Mem[PC + sign-extended(-4)]] R2
(b) Mem[PC + sign-extended(-4)] R2
(c) Mem[R2] PC + sign-extended(-4)
(d) R2 Mem[PC + sign-extended(-4)]
(e) R2 Mem[Mem[PC + sign-extended(-4)]]
Question 12
[1.5 marks] What is the meaning of the following LC3 instruction?
LEA R0, -8
(a) PC R0 + sign-extended(-8)
(b) R0 PC + 8
(c) PC Mem[R0 + sign-extended(-8)]
(d) R0 Mem[PC + sign-extended(-8)]
(e) R0 PC + sign-extended(-8)
The LC3 program below is used for the following 3 questions.
; The inner ; AGAIN
; ; NUMBER SIX |
.ORIG LD LD AND loop ADD ADD BRzp HALT .BLKW .FILL .END |
x3000 R1, SIX R2, NUMBER R3, R3, #0
R3, R3, R2 R1, R1, #-2 AGAIN |
2 x0006 |
Question 13
[2 marks] What is the address of label “SIX”?
(a) 0x3008
(b) 0x3009
(c) 0x3010
(d) 0x3000
(e) 0x300A
Question 14
[2 marks] What is the meaning of the instruction “LD R2, NUMBER”?
(a) R2 Mem[x3008]
(b) R2 Mem[x3006]
(c) R2 Mem[x3007]
(d) R2 x3008
(e) R2 x3007
Question 15
[2 marks] What is the function of the whole program?
(a) Mem[NUMBER] x 3
(b) Mem[NUMBER x 3]
(c) Mem[NUMBER] + 3
(d) Mem[NUMBER x 4]
(e) Mem[NUMBER] x 4
The LC3 program below is used for the following 2 questions.
.ORIG AND LD ADD JSR ADD ADD JSR ADD JSR ADD JSR ADD |
x3000 R0, R0, #0 R6, EMPTY R1, R0, #0 |
||
Push R0, R0, #5 R1, R0, #0 Push R0, R0, #7 Pop R0, R1, #0 Pop R0, R1, #0 EXIT R1, R6, #0 R6, R6, #-1 R6, R6, #1 R1, R6, #0 x4000 x25 |
; First Push
; Second Push |
||
Push
Pop
EMPTY EXIT |
BRnzp STR ADD RET ADD LDR RET .FILL TRAP .END |
||
; Halt |
Question 16
[2 marks] What is the value of R6 before the execution of the instruction “ADD R0, R0, 7” (after the second Push)?
(a) 0x4001
(b) 0x3FFD
(c) 0x4000
(d) 0x3FFF
(e) 0x3FFE
Question 17
[2 marks] What is the value of R7 before the execution of the instruction “ADD R0, R0, 7” (after the second Push)?
(a) 0x3006
(b) 0x3007
(c) 0x300A
(d) 0x3008
(e) 0x3009
The LC3 sub-routine below is used for the following 5 questions. You can assume that the stack sub- routines (Push and Pop) are well written.
Question 18
[2 marks] What is the value of the machine code of the instruction with “LABEL C”?
(a) 0x480A
(b) 0x4810
(c) 0x4809
(d) 0x4811
(e) 0x4808
Question 19
[2 marks] What is the value of the machine code of the instruction with “LABEL A”?
(a) 0x0FF9
(b) 0x0FF8
(c) 0x0010
(d) 0x0FFA
(e) 0x0009
Question 20
[2 marks] What is the value of the machine code of the instruction with “LABEL B”?
(a) 0x0C02
(b) 0x0C04
(c) 0x0803
(d) 0x0C03
(e) 0x0804
Question 21
[3 marks] What is the value printed at the console if the value in R3 is 72010?
(a) 714
(b) 240
(c) 24A
(d) 2D0
(e) 720
Question 22
[3 marks] What is the value printed at the console if the value in R3 is 12010?
(a) 120
(b) 080
(c) 078
(d) 104
(e) 072
2022-06-17