ITEC 1000 Assignment #2
Total = 100 marks (Solutions);
· 5 marks file name and general format
· All questions are based on Englander — Chapters 6 & 7.
· Use a word processor (if you use a non-MS WORD compatible program, e.g., Pages, save as PDF or RTF).
· Both questions and answers must be appropriately formatted (including tables) and well presented with enough explanation.
· Be sure to name the file as your full name in the following format (lowercase), e.g., peggy_carter.docx
· Submit via the upload link provided at the course site any time before or by the deadline, March 26, 11 PM (sharp); late submissions will not be accepted.
· Apply the LMC instruction set below to answer relevant questions.
LMC Instruction Set Instruction
Mnemonic
Numeric Code
Load
LDA
5xx
Store
STO
3xx
Add
ADD
1xx
Subtract
SUB
2xx
Input
IN
901
Output
OUT
902
End
HLT
000
Branch/Jump
BR
6xx
Branch if zero
BRZ
7xx
Branch if zero or positive
BRP
8xx
Data storage
DAT
xxx
1. Trace the program below and summarize what the program does; not a step-by-step description of each instruction. [5 marks]
Address / Mailbox #
Assembly / Mnemonic
Numeric Code
00
IN
901
01
STO 90
390
02
IN
901
03
STO 91
391
04
LDA 90
590
05
OUT
902
06
LDA 91
591
07
OUT
902
08
HLT
000
…
90
DAT 0
000
91
DAT 0
000
2. Complete the table below to construct an LMC program that will accept a set of three numbers as INPUT and then add the first two numbers and output the answer, then subtract the first number from the third and output the answer. The program begins at address 00 and data is stored in address 90. [20 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
00
IN
901
Input first number
01
3. Complete the table below and construct an LMC program that will accept a number INPUT and OUTPUT a sequence of numbers, starting at 1 and finishing with the INPUT (maxNumber). The counter must be initialized to zero each time the program is run. The program will continue (loop) until a 0 is entered. [20 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
00
load zero (from 93) to the accumulator
01
Store the initial count
02
input
03
If zero, branch to halt
04
Store maxNumber
05
LoopTop load count
06
Add step to counter
07
Store count
08
Output
09
Subtract maxNumber
10
If positive, endLoop
11
Jumpt to loopTop
12
endLoop jump to start
13
Halt execution
90
step DAT 1
91
maxNumber DAT
92
count DAT
93
zero DAT
4. Complete the table below to construct an LMC program that will accept two INPUT numbers and then OUTPUT the greater of the two. The program should begin at address 00 and data should be stored in addresses beginning at 90. [25 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
5. Consider the LMC program below in which 2 numbers are entered and added. Suppose the first input entry was stored in mailbox location 00.
a. Would the program have produced the same result?
b. What would have happened if the program were executed a second time?
c. What characteristic of the computer makes this true? [5 marks]
Mailbox
Address
Numeric
Code
00
901
01
306
02
901
03
106
04
902
05
000
06
000
6. If a computer has a 38-bit memory address register. How much memory can this computer address? (Assume: 1 byte/cell; use the most appropriate measure unit). Show your work. [5 marks]
Consider the following LMC instructions found in the given locations in memory.
Mailbox Address
Mnemonic Code
15
LDA 40
16
ADD 41
…
40
723
41
021
7. Show the CPU Fetch/Execute cycle steps and the values of Instruction Register (IR), the Program Counter (PC), the Memory Address Register (MAR), the Memory Data Register (MDR), and Accumulator (A) when the instruction in address 15 is completed. [5 marks]
F/E cycle
Register Values
8. Show the contents of each register as each step of the F/E cycle is performed for instruction 16 in the above program. [10 marks]
F/E cycle
PC
MAR
MDR
IR
A
PC ® MAR
MDR ® IR
IR [address] ® MAR
A + MDR ® A
ITEC 1000 Assignment #2
Total = 100 marks (Solutions);
· 5 marks file name and general format
· All questions are based on Englander — Chapters 6 & 7.
· Use a word processor (if you use a non-MS WORD compatible program, e.g., Pages, save as PDF or RTF).
· Both questions and answers must be appropriately formatted (including tables) and well presented with enough explanation.
· Be sure to name the file as your full name in the following format (lowercase), e.g., peggy_carter.docx
· Submit via the upload link provided at the course site any time before or by the deadline, March 26, 11 PM (sharp); late submissions will not be accepted.
· Apply the LMC instruction set below to answer relevant questions.
LMC Instruction Set Instruction
Mnemonic
Numeric Code
Load
LDA
5xx
Store
STO
3xx
Add
ADD
1xx
Subtract
SUB
2xx
Input
IN
901
Output
OUT
902
End
HLT
000
Branch/Jump
BR
6xx
Branch if zero
BRZ
7xx
Branch if zero or positive
BRP
8xx
Data storage
DAT
xxx
1. Trace the program below and summarize what the program does; not a step-by-step description of each instruction. [5 marks]
Address / Mailbox #
Assembly / Mnemonic
Numeric Code
00
IN
901
01
STO 90
390
02
IN
901
03
STO 91
391
04
LDA 90
590
05
OUT
902
06
LDA 91
591
07
OUT
902
08
HLT
000
…
90
DAT 0
000
91
DAT 0
000
2. Complete the table below to construct an LMC program that will accept a set of three numbers as INPUT and then add the first two numbers and output the answer, then subtract the first number from the third and output the answer. The program begins at address 00 and data is stored in address 90. [20 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
00
IN
901
Input first number
01
3. Complete the table below and construct an LMC program that will accept a number INPUT and OUTPUT a sequence of numbers, starting at 1 and finishing with the INPUT (maxNumber). The counter must be initialized to zero each time the program is run. The program will continue (loop) until a 0 is entered. [20 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
00
load zero (from 93) to the accumulator
01
Store the initial count
02
input
03
If zero, branch to halt
04
Store maxNumber
05
LoopTop load count
06
Add step to counter
07
Store count
08
Output
09
Subtract maxNumber
10
If positive, endLoop
11
Jumpt to loopTop
12
endLoop jump to start
13
Halt execution
90
step DAT 1
91
maxNumber DAT
92
count DAT
93
zero DAT
4. Complete the table below to construct an LMC program that will accept two INPUT numbers and then OUTPUT the greater of the two. The program should begin at address 00 and data should be stored in addresses beginning at 90. [25 marks]
Mailbox #
Mnemonic
Numeric code
Instruction Description
5. Consider the LMC program below in which 2 numbers are entered and added. Suppose the first input entry was stored in mailbox location 00.
a. Would the program have produced the same result?
b. What would have happened if the program were executed a second time?
c. What characteristic of the computer makes this true? [5 marks]
Mailbox
Address
Numeric
Code
00
901
01
306
02
901
03
106
04
902
05
000
06
000
6. If a computer has a 38-bit memory address register. How much memory can this computer address? (Assume: 1 byte/cell; use the most appropriate measure unit). Show your work. [5 marks]
Consider the following LMC instructions found in the given locations in memory.
Mailbox Address
Mnemonic Code
15
LDA 40
16
ADD 41
…
40
723
41
021
7. Show the CPU Fetch/Execute cycle steps and the values of Instruction Register (IR), the Program Counter (PC), the Memory Address Register (MAR), the Memory Data Register (MDR), and Accumulator (A) when the instruction in address 15 is completed. [5 marks]
F/E cycle
Register Values
8. Show the contents of each register as each step of the F/E cycle is performed for instruction 16 in the above program. [10 marks]
F/E cycle
PC
MAR
MDR
IR
A
PC ® MAR
MDR ® IR
IR [address] ® MAR
A + MDR ® A
