Microprocessor execution Flashcards
Where are instructions stored?
ROM - read only memory
How is this piece of code written as microprocessor instructions?
int a = 5;
int b = 3;
int c;
c = a + b;
MOV A, #5. (Move 5 to ‘A’ register)
ADD A, #3. (Add 3 to ‘A’ contents)
MOV 0x0.09, A.
Define a subroutine
A written program that is used any number of times by the main program
-it can be called from anywhere in the program
What are the two words in the assembler are used to call on a subroutine?
ACALL
LCALL
What is the difference between ACALL and LCALL?
-ACALL only takes 2 bytes of program memory and LCALL takes 3
-LCALL can be used to call subroutines located anywhere within the 64K-byte address space of the 8051
Define stack
-a special area in the memory used by the CPU to store information
Define stack pointer
a small register that “points” at an address in the stack
-it points at the top of the stack, where the next item will be stored
Define the PUSH instruction of the stack
-pushes a register or memory location onto the stack
Define the POP instruction of a stack
remove the upmost item from the stack
Define MOVC
Loads the accumulator with a value from memory
Define MOV
Moves bytes betwen registers and ports
Define INC
Increment the value in the accumulator or register
Define SJMP/LJMP
Short/long jump within code
Define XCH
Exchange contents of register with accumulator
Define DJNZ
Decrement register and jump if register is non-zero
define RET
Return from subroutine
What is the purpose of a stack
-way to temporarily store register values
-stores current program states before a subroutine is executed
Define special register function SFR
areas of the memory that control specific functionality of the microcontroller
Give an example of an SFR and what it does
Stack pointer
-indicates where the next value from the stack will be read from RAM
