assignment itech 1000

ITEC 1000 Assignment #2

Total = 100 marks (Solutions);

· 5 marks file name and general format

Instructions:

· 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
PC + 1  PC