Processor Types and Instruction Sets Flashcards
When designing an instruction set what needs to be considered?
● Physical size of the Processor
● How the processor will be used
● Power consumption
What are pros/cons to a small instruction set?
easy to implement but
inconvenient for programmers.
what are pros/cons to a large instruction set?
convenient for programmers but
expensive to implement.
What are the different parts of an instruction?
Opcode, Operands, Result
What is the Opcode in the context of instructions?
It specifies the instruction to be executed
What are operands in the context of instructions?
They specifie the registers, memory location, or constants used in the instruction
What is the result in the context of instructions?
Specifies the registers or memory location where the result of the operation will be placed.
What are the properties of fixed length instruction length?
● Every instruction has the same length
● Reduces the complexity of the hardware
● Potentially, the program will run faster.
What are the properties of variable length instruction length?
● Some instructions will take more space than others
● It is appealing to Assembly code programmers (Not a very
strong advantage. Most programs are written in a high-level language).
● More efficient use of memory.
● Pentium continues using variable length instructions
because of backward-compatibility issues.
What are General Purpose registers?
● They are used to store operands and results
● Each register has a small size: 1 byte, 4
bytes, or 8 bytes.
What is register spilling?
Save registers in memory for later use. The number of registers is limited, so very often it is necessary to use memory or the stack to store temporal values.
What is register allocation?
Choose what values to keep in the registers instead of memory.
What is CISC and its properties?
Complex Instruction Set Computer
● It contains many instructions, often hundreds.
● Some instructions take longer than others to
complete
● Variable Length Instructions
● Examples:
● Move a range of bytes from one place in memory
to another
● Compute the length of a string
● Example: x86
What is RISC and its properties?
Reduced Instruction Set Computer
● It contains few instructions 32 or 64
● Instructions have a fixed length
● Most instructions are executed in one clock
cycle.
● Example: Sparc, Alpha, MIPS, ARM
What is an example of a cisc architecture?
x86
