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1. The content of AC in the basic computer is hexadecimal 789A ; the initial val

ID: 3550697 • Letter: 1

Question

1. The content of AC in the basic computer is hexadecimal 789A ; the initial

value of E is 1; and the initial value of PC is hexadecimal 048.

Determine the contents of E, AC, PC, AR, and IR in hexadecimal in each of the

four independent register reference instructions below. Thus each instruction

starts with the given Initial values.


E AC PC AR IR

Initial 1 789A 048 - -

CLA ? ? ? ? ?

CLE

SPA

SZA




2. (16 points) An instruction at address 047 in the basic computer has I = 0, and an

address part equal to 025 (all numbers are hexadecimal). The memory word at

address 025 contains 5E34 and the content of AC is 789A.

Determine the contents of registers PC, AR, AC, and IR for the two independent

memory-reference instructions below. Each instruction starts with the given Initial

values.

PC AR AC IR

Initial 047 789A

AND ? ? ? ?

BUN



2

3. (24 points) The following program is a list of instructions for the Basic Computer in

hexadecimal code. The computer executes the instructions starting from address

100.

Show the Symbolic instructions with the AC values in the sequence that they are

executed.

Location Instruction

100 7800

101 2109

102 4107

103 7008

104 4106

105 7200

106 7001

107 7020

108 4103

109 8000


Note:

1) The complement of a hexadecimal character is computed such that the hexadecimal

character plus its complement = 15; i.e. the complement of 0 is F and of A is 5.


2) Do not include instructions that are not executed


Location Symbolic instructions comment AC

? ? ? ? ?






4. (22 points) List the locations and hexadecimal code of the Assembly Language

program below.

The locations should be in hexadecimal starting with 100 and ending with 10B.


Location Hexadecimal Assembly Language

instruction code

ORG 100

100 7800 CLA

_______ ________ CLE

_______ ________ STA MM1

_______ ________ LDA MM2

_______ ________ SZA

_______ ________ BUN MM3

_______ ________ BUN MM4

_______ ________ MM3, CIL

_______ ________ CMA

_______ _______ MM4, HLT

_______ _______ MM1, HEX 0

10B _______ MM2, HEX 62C1

END




5. (4 points) List and briefly define four different kinds of assembly language

statements.

The content of AC in the basic computer is hexadecimal 789A; the initial value of E is 1; and the initial value of PC is hexadecimal 048. Determine the contents of E, AC, PC, AR, and IR in hexadecimal in each of the four independent register - reference instructions below. Thus each instruction starts with the given Initial values. An instruction at address 047 in the basic computer has 1 = 0. and an address part equal to 025 (all numbers are hexadecimal). The memory word at address 025 contains 5E34 and the content of AC is 789A. Determine the contents of registers PC, AR, AC, and IR for the two independent memory - reference instructions below. Each instruction starts with the given Initial values. The following program is a list of instructions for the Basic Computer in hexadecimal code. The computer executes the instructions starting from address 100. Show the Symbolic instructions with the AC values in the sequence that they are executed. Note: The complement of a hexadecimal character is computed such that the hexadecimal character plus its complement = 15; i.e. the complement of O is F and of A is 5. Do not include instructions that are not executed List the locations and hexadecimal code of the Assembly Language program below. The locations should be in hexadecimal starting with 100 and ending with WB. List and briefly define four different kinds of assembly language statements.

Explanation / Answer

1.

The corrected table with comments is below:



2.

The corrected table with comments is below:

3.

The table filled in the sequence of execution is as follows:

Location

Symbolic instruction

comment

AC

100

7800 - CLA

Clear the accumulator, AC = 0

0

101

2109 - LDA 109

Load the AC with value at 109

8000

102

4107 - BUN 107

Brach to 107

8000

107

7020 - INC

Increment AC

8001

108

4103 - BUN 103

Brach to 103

8001

103

7008 - SNA

Skip if AC is negative and AC is negative and skips the next instruction

8001

105

7200 - CMA

Compliment AC

7FFE

106

7001 - HLT

Halt the program

7FFE


4)

The Hexadecimal instruction of the give assembly is as follows:

Location

Assembly language

Instruction code in HEXADECIMAL

100

CLA

7800

101

CLE

7400

102

STA MM1

310A

103

LDA MM2

210B

104

SZA

7004

105

BUN MM3

4107

106

BUN MM4

4109

107

MM3 CIL

7040

108

CMA

7200

109

MM4, HLT

7001

10A

MM1 HEX 0

0

10B

MM2 HEX 62C1

62C1


5)

a) CLA - this is an assebly instruction to tell the processor to clear the contents of the Accumulator. Hence Accumulator is loaded with 0x0000.

b) INC - This assembly instruction Increments the contents in the accummulator by 1 and loads the carry(if any) to E.

c) BUN m - This instruction tells the processor to branch unconditionally to the location specified by m.

d) HLT - This instruction is for the processor to HALT the excution of all the instructions.


Hope this helps. Please feel free to contact if any further info is needed.

E AC PC AR IR Comment Initial 1 789A 48 CLA 1 0 49 800 7800 Clears AC CLE 0 789A 49 400 7400 Clears E SPA 1 789A 4A 10 7010 Skip the next instruction if AC is positive. The value in AC is positive so the next instruction is skipped and PC reaches 4A not 49 SZA 1 789A 49 4 7004 Skip the next instruction if AC is zero. The value in AC is not zero so the next instruction is not skipped and PC reaches 49 withput skipping.