Senin, 18 Maret 2013



SYSTEM INPUT / OUTPUT

INPUT OUTPUT SYSTEMFunction Module I / OModule I / O is a component in a computer system responsible forcontrolling an external device or more and also responsible for the exchange of data between the external device to the main memory or to register - registerCPU.Dalam realize this will require internal interface with a computer (CPU andMain memory) and interface with external devices to perform the functions - control functions.In carrying out their functions for I / O module can be divided into several categories,namely:• Control and timing.• Communication CPU.• Communication external devices.• Pem-buffer's data.• Detection error.Measures Handling I / O1. CPU check staus moduli / O Device2. I / O module sends status3. When ready, CPU requests data transfer4. I / O modules retrieve data from the device5. I / O module data transfer in a variety of output keCPU diinginakanMethod of Accessing I / O1.MemoriMapped I / OIn memory-mapped I / O, there is a single space for memory locations and device I / O. CPU register status and treat the data register I / O module as memory locations andusing the same machine instructions to access both the device memory and I / O.Konskuensinya is required for single-channel and single-channel readoutfor writing. The advantage of memory-mapped I / O is efficient in programming, but it takes up a lot of memory address space.2. Isolated I / OIn the technique of isolated I / O, to separate the memory addressing space and the addressing space for I / O. With this technique required a bus that is equipped with a channel memory plus reading and writing command line output. Advantages isolated I / Ois little instruction I / O.Method of Operating system I / O1. I / O FixedOn the I / O programmed, data is exchanged between the CPU module and I / O. CPU executes programs that provide I / O to the CPU directly, such as data transfer, sending the read or write, and monitoring devices. The weakness of this technique is the CPU will wait until the I / O operation is complete I / O module so that it will waste time, let alone CPU faster processing operations.2. I / O Instruction (Demand Driven)driven I / O allows a process not waste - waste of time. The process is CPU issued an I / O module I / O, along the order of I / O modules run I / O then the CPU will execute the command - command lainnya.Apabila I / O module has finished running the instructions given to him will interrupt the CPU that the task has been completed.3. Direct Memory Access (DMA)The technique described previously is I / O programmed and Interrupt-Driven I / O has a weakness, which is a process that occurs in the module I / O still involves CPU directly. This implies:• The rate transfer I / O operations that depend on the speed of the CPU.• Working CPU impaired because of interruptions directly.Starting from the above drawbacks, especially for handling large volume of data transfer developed better techniques, known as the Direct Memory Access (DMA). Working principle shall delegate the DMA is working CPU I / O to DMA, the CPU would only be involved early in the process to provide complete instructions on DMA and End process. Thus, the CPU can execute other processes without much annoyed by the interruption.Data Transfer1. Transfer Formata. Parallel: all bits transmitted simultaneously on the characters within a certain time limit transmissionb. Serial: data shipped sequentially in a single komnikasi line, so that the sender and receiver must share the deadline for submitting the characters into multiple sub-interval delivery
             
 
Parallel transfer is faster because it has a lot of transmission lines, but no bias is applied at a distance that is too long, because it can happen anatar channel interference2. Transfer Modea. Synchronous:
            
Speed ​​device I / 0 was varied in abundance serial data sent and turns in a period that has been applied, the transfer rate is set on the device I / O with low speedb. Asynchronous
            
The process of back and forth in the forward control signal from the sender to the receiver.Interfacing Devices I / On A tool for connecting a piranati digunakana with the CPU through the BUSn General Function:Synchronize the data transfer between CPU and device I / OFunction Details:1. Provider status of device I / O to the CPU2. Have the ability to interrupt / DMA3. Able to transfer to the device CPU instructions4. Able to serve as a buffer storage of data transfer5. Being able to test the similarity of data6. Being able to decode and encode the data7. Have special facilities: parallel to serial conversion of data, character encoding F1, F2
    
BACKSPACE, DELETE, etc.8. Provides operating status signalsStrukrur Interface:1. Register: Full (CR): recorded instructions and information in the device
    
Status (SR): record the status of the device and issue an error message
    
Data Input (S) and Data Ouput: as a data buffer for input and output operations2. BUS
    
Receiver: handle data input
    
Transciever: bidirectional data circuits to handle both input and output
    
Driver / Buffer Bus: tri state circuit that stores the information bus.System Processor I / On General Purpose computers that contain a number of channels of DMA, the CPU itself and run in paralleln Function:As a front end tool that handles every aspect of I / O and provides a controller I / O, called an I / O ChannelInstructions IOP:1. Data Transfer Instructions
    
Input (reading), Output (writing) and reading status information2. General Instructions Purpose
    
Instructions arithmetic, logic, branching (conversion, operation priorities, evaluation addresses, jump instructions)3. Full Instructions
   
Instructions for handling function device I / O special which was not involved in the data transfer example: moving head R / W to determine the location and the track record on the disc.Format Instruction IOP:1. Field Opcode: representation of the type of operation2. Field Memory address: starting address block of memory used to transfer3. Field Word Count: the number of word to be transferred4. Full Field: for functions device I / O special5. Filed Status: for the purposes of communication and record keeping.


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