Chapter 6 Assembly Language Programming

Question 1

What language does the CPU recognize?

Answer 1

The CPU recognizes only machine code

Question 2

In what kind of format is machine code?

Answer 2

Machine code is in binary format.

Question 3

What is a machine code instruction?

Answer 3

A machine code instruction is a binary code with a defined number of bits that comprises an opcode and most often one operand.

Question 4

What is the machine code comprised of?

Answer 4

Opcode - is the portion of a machine language instruction that specifies the operation to be performed
Operand - the data to be processed
Address mode - Stores address
Register addressing

Question 5

Write an example of a register transfer notation and its meaning?

Answer 5

CU control unit

Question 6

What other language is a better alternative to machine code for programmers and why?

Answer 6

Assembly language because it helps in writing the program with comments and symbolic names for constants, macros and subroutines can be used more often in the code.

Question 7

What instructions does the assembly language need to tell the assembler how to convert the code in machine code?

Answer 7

Directives and system calls

Question 8

What are addressing modes?

Answer 8

Addressing modes are the ways of identifying the value that is to be written to the register.

Question 9

How are the types of addressing modes identified

Answer 9

Immediate: the value to be used as it is in the instruction
Direct: An address which holds the value to be used in the instruction
Indirect: An address that holds the address of the value to be used in the instruction
Indexed: An address to which must be added what is currently in the Index Register (IX) to get the address that holds the value to be used in the instruction

Question 10

In an instruction what can the operand be?

Answer 10

<address>
#n is a denary number, when it is direct addressing
</address>

Question 11

Which are the data movement instructions?

Answer 11

LDM
    Immediate addressig
    #n
LDR
    Immediate addressig
    #n
LDD
    Dierct addressing
    <address>
LDI
    Indirect addressing
    <address>
LDX
    Indexed addressing
    <address>
STO
    Storing the contents of ACC
    <address></address></address></address></address>

Question 12

Which are the arithmetic instructions?

Answer 12

ADD
    Adds the contend of the ACC with the content from the address
    <address>
INC
    Increases value with 1

DEC
Decreases value with 1

</address>

Question 13

Which are the comparisons and jumps instructions?

Answer 13

JMP
Jump to address
<address>
CMP
Compare ACC content with register content
<address>
CMP
Compare ACC cotent with n
#n
JPE
Jump to address if previous comparison was true
<address>
JPN
Jump to address if previous comparison was NOT true
<address></address></address></address></address>