A microprocessor using a 3 MHz clock has three T ' states in each machine cycle. What is the time taken to complete the execution of an instruction if the instruction cycle of this instruction needs 4 machine cycles?
Number of T-states in each machine cycle = 3 So, number of T-states in 4 machine cycles = 3 x 4 = 12
Given, f = 3 MHz
Thus, time required for execution of the instruction
Which of the following instruction will alter the contents of accumulator?
Hence, the contents of A does not change.
The addressing mode in which the machine language instruction itself includes the data is called
In immediate addressing mode, an 8 bit or 16 bit data Is given In the instruction as operand.
In an 8085 microprocessor, the accumulator contents are AAFI. After the execution of the instruction ‘CPI 99PT in the microprocessor
Initially contents of accumulator A = AA H.
The instruction CPI 99 H compares the data 99H w ith the content of accumulator (A). This comparison is made by subtracting 99 H from contents of A i.e. AA H.
The contents of accumulator will remain unaffected but status of result will be reflected by flags
Hence, after comparison both carry and zero flags will be reset
The content of TEMP location after the execution of the following program in a 8085 microprocessor is:
MVI B, 00H
MVI A, IC H
Decrement the content of B by one (initially B = 00 H)
B= FF H
D A A ; D A A instruction changes the binary values of contents of accumulator to BCD.
Since lower order nibble of A is more than 9 (i.e. C), AC flag is set and upper nibble is less than 9, therefore DAA adds 0110 H to lower order nibble of A to adjust binary result to Binary coded decimal.
The following program is executed in the 8085 microprocessor:
What are the contents of the accumulator after the execution of above program?
2040 HLT ; Halts the execution of program Hence, the content of accumulator after the execution of given program are 40 H.
What is the addressing mode used in the instruction PUSH D
PUSH D stores the content of register pair DE on two top locations of stack, it is a 1 byte instruction and uses register indirect addressing mode.
What is the effect of a DAD H instruction?
An instruction cycle is the time in which, a hardwired controlier completes four functions. The correct sequence of these functions is
An instruction cycle is the time in which, a hardwired controller completes the following four functions;
(i) fetching of code from memory
(ii) updating the program counter
(iii) decoding of the instruction code
(iv) execution of the instruction
Which of the following instruction does not use the stack?
CALL and RET instruction uses stack while JMP instruction does not uses stack.