CPU functions
- Running programs - programs that are stored in the main way to take instruction - instruction, testing and instruction exsecution one by one according to the groove.
- The view most simple program execution process is to take the processing instruction that consists of `two steps, namely:
* Operation reading the instructions (Fetch)
* Operation of instruction (execute)
* Operation of instruction (execute)
Instruction cycle
- Consists of Fetch cycle and the cycle execution
Fetch cycle - execution
- At each cycle instruction, the CPU will initially read instructions from memory.
- There are registers in the CPU, which functions control and calculate the next instruction, called the Program Counter (PC)
- PC will add one calculation each time the CPU to read the instructions.
- Instructions - read the instructions that will be made in the Instruction Register (IR).
- Instructions - in the form of this instruction code - the code binner the interpretation can be done by the CPU and the action required.
The CPU Action
- CPU - Memory, the movement of data from the CPU to memory and vice versa.
- CPU and I / O, the movement of data from the CPU to the module I / O and vice versa.
- Data processing, the CPU establish a number of arithmetic and logic operations of the data.
- Control, is the instruction to control functions or work. For instance affairs conversion instruction execution.
Details cycle execution
- Instruction Address Calculation (IAC), namely Calculation or determine the address of the next instruction that will be executed.
- Involving the number of permanent additions to address previous instructions.
>> For example, if the length of each 16 bit instructions have
a long memory when 8 bits, then add 2 to address previously.
a long memory when 8 bits, then add 2 to address previously.
Cycle execution
- Cycle for an instruction execution can involve more than a reference to the memory.
- In addition, an instruction can determine an operation I / O.
- Instruction Fetch (IF), read the instructions from the authorities or the location of memory to the CPU.
- Instruction Operation Decoding (IOD), which analyzes the instructions to determine the type of operations that will be formed and operand that will be used.
- Operand Address Calculation (OAC), which determine the address operand, this is done when the reference operand involved in memory.
- Operand Fetch (OF), is taking operand from memory or from the module I / O.
- Data Operation (DO), which is formed in which the operating instructions.
- Operand store (OS), the results of execution to save the memory.
Figure cycle instructions
Function Interruptions
- Mechanism termination or transfer of the processing instructions in the CPU to the routine interruptions.
- Almost all modules (memory and I / O) have a mechanism that can work to interrupt CPU.
Goals Interrupts
- In general, for management execution routine instructions to effective and efficient inter-module and the CPU - the module I / O and memory.
- Each component of the computer can run tasks simultaneously, but the control is located on the CPU in addition to the speed of execution - each module is different.
- Can work as the synchronization between the modules
Kind of class signal interruptions
- Program, the interruptions are raised with several conditions that occur on the results of program execution.
* Example: aromatic overflow, the division of zero, operation illegal.
- Timer, is the interruption of the timing raised in the processor.
* Signals allows operating systems to run certain functions regularly.
Kind of class signal interruptions
- I / O, signal interruptions that are raised by the module I / O notification in respect of conditions of error and a resolution of the operation.
- Hardware failure, is raised by the interruption of power failure or memory parity errors.
The process Interrupt
- With the mechanism interruptions, the processor can be used for executing other instructions.
- When a module is finished and ready to run the duty to receive the next assignment, the module will send a request interruptions to the processor.
The process Interrupt
- Then, the processor will stop the execution of run to manhandle routine interruptions.
- Once the program is completed, the interruption processor will continue the program execution again.
- When interruptions received signal processor there are two possible actions, namely interruptions accepted or rejected suspended and interruptions.
Interruptions Suspended
What do processors?
- Processors suspend the execution of programs that run and save the context. This is the address of store instructions that will be exercised and other relevant data.
- Processors set the program counter (PC) to address early routine Interrupt handlers.
Cycle execution by the processor with the function of interruptions
Operating system complex
- Interruption double (multiple Interrupt).
* For example, a computer will receive the request interruptions
during the printing process is completed with
the printer, in addition to the possible channels
of communication will submit a request
each time the interruption of data arrived.
during the printing process is completed with
the printer, in addition to the possible channels
of communication will submit a request
each time the interruption of data arrived.
- Can be taken two approaches to handle this double interruption.
Interrupts dual approach
There are 2 approaches:
- This approach is called sequential processing interruptions / sequential.
* Reject or other interruptions do not allow the interruption of a processor handled.
* Once completed processor handles the interruption of a new handled other
interruptions.
* Once completed processor handles the interruption of a new handled other
interruptions.
Interrupts dual approach
- Processing interruption nest that is defining priorities for the interruption.
* Interrupt Handler: allow interruptions priorities higher handled first.
Multiple Interrupts - Sequential
Multiple Interrupts - Nested
Case
- A system has three devices I / O: printers, disk, and communication channels, each - their priorities 2, 4 and 5. How will the process interruptions?
- At the beginning of the printing system with a printer, when there is data on the delivery channel of communication so that communication module to request interruptions.
- The transfer of the execution of interruption of communication modules, the printer interruptions while suspended.
- When execution communication module, the interruption disk, but a lower priority because of the interruption suspended disk.
- After the interruption of communication modules will be completed by interruptions that have higher priority, namely the disk.
- When the disk is finished interruption, the execution interruptions printer. `Then the execution of the main program.
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