What is Operating System?

              Operating System works as an interpreter between computer hardware and application. Operating System works as a user interface.

Difference between branch and call subroutine instruction

Difference between branch and call subroutine instruction?

              Branch instruction:

• Every time it is not possible to use line-sequence of instruction, sometime we need breakup in our program according to some condition this is nothing but branching and to perform these branching we require some instruction that is called branch instruction

       Eg:       MOV                    R0,     num1
                   MOV                    R2,     num2
                   CMP           R0,     R1
                   JB .             next
                   Sub            R0,     R1
                   MOV                    R2,     R1
       Next:   Sub            R1,     R0
                   MOV                    R2,     R0

• Here the task of IB. is it compairs the two Numbers i.e. R0, and R1, if R0, < R1, then it goes to next and execute the instruction otherwise it execute the instructions just next to it.
• The IB is your branch instruction.

       e.g. : IC, INC, IZ, INZ, IB, INB etc.

       Subroutine instruction:

• Subrouting instruction is the instruction which is used to call the particular procedure.
• In your main program we call particular procedure execute that procedure and then again switch to main program.
• The instruction used for. This called to procedure and getting switch to main program is called subroutine instruction.

Interrupt handling of 68000.

Interrupt handling of 68000.

In 68000 the address of the interrupt handler was placed at 4x interrupt handler number thus if interrupt 3 occurred, you went to address 12 ten, at the address was the address of the handler.
With many different I/O devices that can be interrupt controller. I/O devices are hooked up to the PIC and the PIC is the only device that sends the interrupt.

MOV instruction of 8051

MOV instruction of 8051.

MOV copies the value of operand 2 into operand 1 the value of operand 2 is not affected. Both operand 1 and operand 2 must be in Internal RAM. No flags are affected unless the instruction is moving the value of a bit into the carry bit in which case the carry bit is affected or unless the instruction is moving a value into the PSW register.

Synchronous bus & Asynchronous bus

Synchronous bus:

• Transmitter and receivers are synchronized of clock.
• Data bits are transmitted with synchronization of clock.
• Character is received at constant Rate.
• Data transfer takes place in block.
• Start and stop bit are required to establish communication of each character.
• Used in high – speed transmission.

Asynchronous bus:

• Transmitters and receivers are not synchronized by clock.
• Bit’s of data are transmitted at constant rate.
• Character may arrive at any rate at receiver.
• Data transfer is character oriented.
• Start and stop bits are required to establish communication of each character.
• Used in low – speed transmission.

Volatile memory and NonVolatile memory

Nonvolatile memory: If memory can hold data even if power is turned off, then such type of memory are called nonvolatile memory.

Volatile memory: If memory Remove the data if power is turned OFF, then such type of memory are called volatile memory.