1. CS334: MIPS language _Mars simulator Lab 2_1

2. Part1:MIPS assembly language. Questions.
Contents:
introduction.
Part1:MIPS assembly language.
Questions.
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3. Assembly Language
Instructions are the primitive operations that the CPU may execute.
Different CPUs implement different sets of instructions. The set of instructions a particular CPU implements is an Instruction Set Architecture (ISA).
Examples: Intel 80x86 (Pentium 4), IBM/Motorola PowerPC (Macintosh), MIPS, Intel IA64, ...
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4. MIPS Architecture
MIPS – semiconductor company that built one of the first commercial RISC architectures
MIPS is simple, elegant.
Assembly Operands are registers
Groups of 32 bits called a word in MIPS
The Text segment shows you:
Address -- where this instruction is stored in memory
Code -- the machine code of the instruction
Basic -- [not too helpful at this point]
Source -- the original instruction you typed in
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5. List of Instructions
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6. Part 1: MIPS .text $t1 = 3 + 5 + 9 addi $t1, $zero, 3
Start the program with:
.text
This says that the following are program instructions (and not, e.g.,data).
Let's do the following:
$t1 =
First, let's put 3 in $t1:
addi $t1, $zero, 3
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7. Part 1: MIPS (cont…) addi $t1, $t1, 5 addi $t1, $t1, 9
This says to take what is stored in register $zero, add 3 to it, and put the result in register $t1.
$zero ALWAYS contains 0, so this puts into register $t1
Now we want to add 5 to our running sum:
addi $t1, $t1, 5
And then we want to add 9:
addi $t1, $t1, 9
Save and Assemble the program (run it). You will see that $t1 contains 0x
The 0x just means that the number following it is in hex.
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8. Performing the program
Pc :
Special register keeping the address of next instruction .
Read the code from memory by pc .
$at : assembler temporary as handle for save value .
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9. Questions Answer: 17 program counter = 0x00400000
Question 1: What decimal number is 0x ?
Answer: 17
Question 2: before the first instruction is executed (the program counter is the register labeled "pc")
program counter = __________
program counter = 0x
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10. Cont..)) Questions program counter = 0x00400004 $t1 = 0x00000003
Question 3: after the first instruction is executed:
program counter =
$t1 =
program counter = 0x
$t1 = 0x
Question 4: after the second instruction is executed:
program counter =
$t1 = ____________
program counter = 0x
$t1 = 0x
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11. Cont..)) Questions program counter = 0x0040000C $t1 = 0x00000011
Question 5: after the third instruction is executed:
program counter = ___________
$t1 = _____________
program counter = 0x C
$t1 = 0x
Question 6: Complete this sentence:
After each instruction, the PC is incremented so that it contains:
1) A bit which is a 0 or 1.
2) A byte which is 8 bits.
3) A word which is 4 bytes.
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12. Cont..)) Questions
Hint : In a MIPS architecture, each byte has its own address (the byte is the "addressable unit").
Question 7: How big are instructions in MIPS?
Number of bits =
Number of bytes =
Number of words = 32 4 1
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13. conclusion
This shows a good way to learn assembly language. Enter and assemble instructions; this will show you the machine code that is produced. Then, step through execution so you can see the effects of the individual instructions.
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14. exercise to perform the calculation: f = (g + h) - (i + j) g= 5 h= -20
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16. H.W for absent
You are given the following two numbers in two’s complement representation.
Perform the binary addition and subtraction. Did signed overflow occur?
determined whether or not overflow occurred.
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