LS-3 ASM Flashcards
Create a simple program that loads data into register one, perform a bit-wise not operation and store that in result.
Each non blank line in lc-3 is what?
- An instruction (ld r1, data)
- An assembler directive (.orig x3000)
- A comment
What is the typical form an instruction has in LC-3?
Label OpCode Operands ;Comments
What does an instruction consis of?
An opcode and one or more operands
What are opcodes?
What does Operands do? And what are typical operands?
Line by line, what does the following code do?
How would you load data into register 1?
ld R1, data
How do you store the contents of register 3 into result?
st R3, result
What can you think of labels as?
They are a symbolis name for a memory location (the line is usually denoted by a hex value)
How do Assembler Directives work?
What are the Assembler Directives/What do they do
In general what are traps?
What are the traps and what do they do?
In general how does the Assembly process work?
What happens during the first pass of the assembly process
What happens during the second pass of the assembly process
Each line scanned again
Everything translated into machine languge
Does using the symbol tables, fillng in labels like a macro.
Fill memory loctions as directed by assembly directives
In general what is Linking and Loading?
What are the output files the Assembler generates?
How do you read in a character and how do you print that character to console?
How do you print a string to console?
In general, what is a condition code?
There is a process to determine based on the last arithmatic/logic expression if the result was zero, poisitive or negative.
What are the instructions that affect the condition code?
What is the condition code after each line of code?
How does conditional branching work?
Create a simple loop that loops 10 times
What are the 7 forms of branching and when do they work?
Provide the code for a simple if statement that checks if R1 is positive after an add instruction, If it is, it executes code starting from label if. Otherewise it branches to label skip
Provide an example of an If-Else Statement
Create a while loop that reads a chracter and prints it 10 times using a loop
Create a while loop that iterates through the numbers from 1 to 100 and summ all the odd numbers and store result in register r2
When branching what is the limitation for distance from PC counter?
Must be within -255 and 256 words of the BR instruction (because we only have 9 bits to hold the offset)
What is the symtax for an unconditional branch?
How do you overcome the limitation of distance from pc relative?
Using LEA, one can store in the register the address (pointer) of the next instruction.
Example:
br loop (loop label needs to be -255 to 256 of the br intruction
loop
LEA r4, EXIT
jmp (or br) r4
can jump anywhere in memory space
