Chap 2 - PART 1 - Language of the Computer Flashcards
Image showing a Simplified Overview of compiling your program
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Assembly language
List the characteristics of the assembly language:
RISC
RISC: Reduced Instruction Set Computer
- Provides a small set of instructions, each designed to attain a small task
- The programmer may need to use more instructions to complete some given task
- Less straining on the hardware
- eg. MIPS, ARM, RISC-V
List the characteristics of the assembly language:
CISC
CISC: Complex Instruction Set Computer
- Provides instructions skilled in executing multi-step operations
- Same task can be achieved using less instructions than RISC
- Difficult to implement on the hardware
- eg. x86
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Table showing the differences between RISC vs CISC
Describe the arithmetic operations:
State: Design Principle 1
Arithmetic Example:
- C Code:
f = (g+h) - (i+j);
- Compile the code above to MIPS Code
Describe: Registers
- This refers to the small bit of memory in the cetral processing unit (CPU)
- It is used in assembly language to perform different instructions
- Limited number of special locations built directly into the hardware
- Operations can only be performed on these; registers are the tiniest, fastest, and most expensive type of memory
Benefit:
- Since registers are directly in hardware, they are very fast (faster than 0.25ns)
- Unlike HLL like C or Java, assembly cannot use variables
- why not? find out? maybe to keep hardware simple?
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Registers inside the processor
- State the drawback of registers:
- State the solution for this drawback:
- Why are there 32 registers only in MIPS
- What is a group of 32 bits called?
- Since registers are in hardware, there is a predetermined number of them, hence, limited.
- The solution is that MIPS code must be very carefully put together to efficiently use registers. In other words, the power is in the hand of the programmer.
- 32 bits because smaller is faster, however, too small is bad
- group of 32 bits is called a word. EACH MIPS register is only 32 bits wide.
Describe:
the Constant Zero
MIPS register 0 ($zero) is known as the constant zero
- it cannot be overwritten
Useful for common operations
- eg. Move between registers
- add $t2, $s1, $zero
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Register usage
About register operands:
- what types of instructions uses register operands?
- Describe the characteristics of MIPS that has a 32x32 bit register file
- arithmetic instructions
- Use for frequently accessed data ; numbered 0 to 31
List the Assembler names for register operands
$t0, $t1, … $t9, for temporary values
$s0, $s1, …, $s7, for saved variables.
State:
the design principle 2
Smaller is faster:
- c.f. main memory: millions of location
Register Operand Example:
- C code:
- f = ( g + h ) - ( i + j );
- f, …., j in $s0, …, $s4
- Compile the code above in MIPS
List the main memory that is used for composite data
- arrays
- structures
- dynamic data
- How to apply arithmetic operations? What are the steps?
- Load values from memory into registers
- Store result from register to memory
Memory is byte addressed, each address identifies an?
each address identifies an 8 bit style
Memory Operand Example 1
C code:
- g = h + A[8];
- g in $s1, h in $s2, base address of A in $s3
Compile the code above in MIPS code:
- Note that: index 8 requires offset of 32
- There are 4 bytes per word
Memory Operand Example 2
Code:
- A[12] = h + A[8];
- h in $s2, base address of A in $s3
Compile the code above in MIPS code:
- Note that: Index 8 requires offset of 32
List:
the register numbers format
MIPS R-Format Instructions includes?
Instruction fields consist:
- op: operation code (opcode)
- rs: first source register number
- rt: second source register number
- rd: destination register number
- shamt: shift amount (00000 for now)
- funct: function code (extends opcode)
Image showing the MIPS R-Formate Instruction
R-Format Example:
add $t0, $s1, $s2
MIPS I-Format Instructions:
List the instructions included in this format
Immediate arithmetic and load/store instructions
- rt: destination or source register number
- Constant: -215 to + 215 - 1
- Address: offset added to base address in rs
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Stored Porgram Computers
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Logical Operations:
These are instructions for bitwise manipulation.
They are useful for extracting and inserting groups of bits in a word
Shift Operations: R-Format:
Explain it
shamt: how many positions to shift
shift left logical:
- shift left and fill with 0 bits
- sll by i bits multiplies by 2i
Shift right logical:
- shift right and fill with 0 bits
- srl by i bits divides by 2i (unsigned only)
Image Showing R-Format: Shift Operations:
AND Operations:
Why is it useful?
It is useful to mask bits in a word
- select some bits, clear others to 0
- and $t0, $t1, $t2
image explaining this further:
OR Operations:
Why is it useful?
It is useful to includes bits in a word:
- Set some bits to 1; leave others unchanged.
- or $t0, $t1, $t2
Image showing the above eg:
NOT operations:
why is it useful?
It is useful to invert bits in a word:
- change 0 to 1, and 1 to 0
Note: MIPS has NOR 3-Operand Instruction
- a NOR b == NOT (a OR b)
- nor $t0, $t1, $zero
Image showing the above eg:
Conditional Operations Example:
C Code:
- if ( i == j ) f = g + h;
- else f = g - h;
- f, g, … in $s0, $s1,….
compile the above code in MIPS:
Compiling Loop Statements Example:
C Code:
- while (save[i] == k) i += 1;
- i in $s3, k in $s5, address of save in $s6
Compile the above code in MIPS code:
Define:
Basic Blocks
A basic block is a sequence of instructions with:
- no embedded branches (except at the end)
- No branch targets (except at the beginning)
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Branch Instruction Design:
Why not blt, bge, etc?
