Instructions Flashcards
What defines a stored program architecture?
The program stored in memory defines the microprocessor’s functionality
What is the difference between the PIC 16F84A and MIPS architectures?
PIC 16F84A uses 14-bit instructions and 8-bit data words (Harvard) while MIPS uses 32-bit instructions and data words (Von Neumann)
What are the key fields in an instruction?
Opcode (operation) Operands (data) and optionally a Function or Modifier
What is the purpose of the opcode in an instruction?
It specifies the operation the instruction will perform such as ADD or SUB
What are the three types of MIPS instructions?
R-Type (arithmetic/logical) I-Type (immediate values) and J-Type (jump/branch)
What is an R-Type instruction in MIPS?
An instruction used for arithmetic and logical operations like ADD or SUB
How are opcodes represented in the PIC 16F84A?
With 6 unique bits identifying each operation
What does an assembly mnemonic represent?
A human-readable symbol for a machine code operation such as LDA or ADD
What is immediate (literal) addressing?
Data is contained directly within the instruction itself
How does direct (absolute) addressing work?
The instruction specifies the exact memory address of the data
What is indirect addressing?
A register stores the memory address where the data is located
What is relative addressing used for?
To specify a memory address using a base address and an offset
What is the stack in microprocessor design?
A special memory area used for temporary data storage
What is the difference between PUSH and POP operations in a stack?
PUSH saves data to the stack while POP retrieves data from the stack
What does LIFO mean in stack management?
Last In First Out - the last item added is the first one retrieved
How are instructions structured in MIPS?
They include fields like opcode, source registers, destination registers and function modifiers
Why might an opcode have extra bits in its design?
To simplify decoding and organization of instructions
What is source-destination sharing in instructions?
When one register acts as both a source and a destination to save opcode space
What is memory-memory architecture?
architectures that access the main memory using the large binary addresses associated with that memory
What is register-register architecture?
Data is firstly loaded from memory into registers.
The instruction only then needs to specify which of the small number of registers to use as inputs and another register to receive the result.
