Chapter 28 Low-level Programming

Question 1

Which are the Data movement instructions used in the Processor?

Answer 1

LDM #n //Immediate addressing. Load the number n to ACC

LDD <address> //Direct addressing. Load the contents of the location at the given address to ACC

LDI <address> //Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC

LDX <address> //Indexed addressing. Form the address from <address>+ the contents of the index register. Copy the contents of this calculated address to ACC

LDR #n //Immediate addressing. Load the number to IX
STO <address> //Immediate addressing. Load the number n to IX

STX <address> //Indexed addressing. Form the address from <address>+ the contents of the index • register. Copy the contents from ACC to this calculated address

STI <address> //Indirect addressing. The address to be used is at the given address. Store the contents of ACC at this second address
</address></address></address></address></address></address></address></address>

Question 2

Which are the Arithmetic operations used in the Processor?

Answer 2

ADD <address> //Add the contents of the given address to the ACC

INC //Add 1 to the contents of the register (Ace or IX)

DEC //Subtract 1 from the contents of the register (ACC or IX) </address>

Question 3

Which are the Comparison and jump instructions used in the Processor?

Answer 3

JMP <address> //Jump to the given address

CMP <address> //Compare the contents of ACC with the contents of <address>

CMP #n //Compare the contents of ACC with n

JPE <address> //Following a compare instruction,jump to <address> if the compare was True

JPN <address> //Following a compare instruction, jump to <address> if the compare was False </address></address></address></address></address></address></address>

Question 4

Which are the Input and output instructions used in the Processor?

Answer 4

IN //Key in a character and store its ASCII value in ACC

OUT //Output to the screen the character whose ASCII value is stored in ACC

Question 5

Which are the Bit manipulation instrcutions used in the Processor?

Answer 5

AND #n //Bitwise AND operation of the contents of Ace with the operand

AND <address> //Bitwise AND operation of the contents of ACC with the contents of <address>

XOR #n //Bitwise OR operation of the contents of Ace with the operand

XOR <address> //Bitwise XOR operation of the contents of Ace with the operand

OR #n //Bitwise OR operation of the contents of ACC with the operand

OR <address> //Bitwise OR operation of the contents of ACC with the contents of <address>

LSL #n //Bits in Ace are shifted n places to the left. Zeros are introduced on the right hand end

LSR #n //Bits in Ace are shifted n places to the right. Zeros are introduced on the left hand end
</address></address></address></address></address>

Question 6

Which is the instruction used to return control to the operating system?

Answer 6

END //Retrun control to the operating by ending the process

Question 7

What is the structure of an instruction?

Answer 7

:

Question 8

What is the structure of assigning data to a label?

Answer 8

:

Question 9

What does in the assembly code in this chapter ACC mean?

Answer 9

Accumulator

Question 10

What does in the assembly code in this chapter IX mean?

Answer 10

Indexed Register

Question 11

What does in the assembly code in this chapter # mean?

Answer 11

Immediate addressing

Question 12

What does in the assembly code in this chapter B mean?

Answer 12

A binary number

Question 13

When & occurs what does it mean?

Answer 13

When & occurs it means that a hexadecimal code is written for example &4A

Question 14

What does in the assembly code in this chapter <address> mean?</address>

Answer 14

<address> can be an absolute address or a symbolic address</address>

Question 15

How to assign 34 to A in assembly code?

Answer 15

LDM #34

STO A

Question 16

Show an example of adding a value in assembly code?

Answer 16

LDD B
ADD A
STO B

Question 17

Show an example of incrementing a value in assembly code?

Answer 17

LDD B
INC ACC
STO B

Question 18

Show an example of making a negative value in assembly code?

Answer 18

LDD A
XOR #&FF
INC ACC
STO A

Question 19

Show two examples of making an IF statement in assembly code?

Answer 19

// first example
LDD A #
 CMP #0 
 JPN ENDIF 
 THEN: LDD B 
 INC ACC 
 STO B 
 ENDIF: ...

// second example
LDD A 
 XOR #&FF 
 INC ACC 
 ADD B 
 CMP #0 
 JPN ELSE 
 THEN: LDM #89 
 OUT 
 JMP ENDIF 
 ELSE: LDM #78 
 OUT 
 ENDIF:...

Question 20

Show an examples of making a REPETITION in assembly code?

Answer 20

 LDM #0 
 STO A 
 LOOP: LDM #42 
 OUT 
 LDD A 
 INC ACC 
 STO A 
 CMP #5 
 JPN LOOP

Question 21

Show an examples of making an INPUT in assembly code?

Answer 21

IN

STO A

Question 22

Show an examples of making an OUTPUT in assembly code?

Answer 22

LDR #-1 
 LOOP: INC IX 
 LDX B 
 OUT 
 CMP #13 
 JPN LOOP

Question 23

Show an examples of inputing A as a longer string in assembly code?

Answer 23

LDR #-1 
 LOOP: INC IX 
 IN 
 STX A 
 CMP #13 
 JPN LOOP

Question 24

What kind of address is an absolute address?

Answer 24

An absolute address is a numeric address meaning that it can only point to one exact point or address

Question 25

What is a relative address and how does it work?

Answer 25

A relative address is an address that is relative to a base address so depending on the base address it can point to an address and when the base address changes so does the point or address to which it points

Question 26

Write or say an example of a code that uses relative addressing.

Answer 26

LDM #0 
 STO [BR] + 10 
 LDM #42 
 OUT 
 LDD [BR] + 10 
 INC ACC 
 STO [BR] + 10 
 CMP #5 
 JPN [BR] + 2 
 END 
 0

Question 27

What happens in indirect addressing?

Answer 27

In indirect addressing the address to be used is at a given address.