I20 FAQ

I2O

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I2O

What is I2O?
I2O (Intelligent I/O) is an open architecture for the development of device drivers, in a network system environment. This acrchitecture is independent of the operating system, processor platform, and I/O system bus. This specification allows standardization of the development of device drivers so that a portion of the device driver can be offloaded to an embedded processor on another hardware platform.
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How does I2O work?
A device driver interfaces a specific hardware device to a specific operating system. The top portion of the device driver adapters the operating systems and calls into I/O transactions.
The bottom portion of the driver contains vendor-specific code, which adapts the hardware level interface of the I/O adapter to the functions required for that particular class of device. For example, all network adapters perform the same class-specific functions but have varying register interfaces.
The I2O Specifications calls for splitting the device driver into two modules, one that contains all the OS-specific code and the other that contains all the hardware-specific code. The OS vendor needs to produce only one OS-specific module for each class of I/O device. The hardware vendor has to produce only one single version of the hardware device module for its I/O adapter.
The device driver can be split more than once, creating stackable drivers. This enables an independent software vendor to add value by providing the capability to expand the system, independent of both the hardware and the OS.
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What are some key benefits of I2O?
There are many advantages to using I2O, but two main benefits are:
  1. Cost Reduction
    By enabling the system vendor to create an I/O platform that can support a number of non-intelligent I/O adapters, I2O provides economy of scale. Where a single I/O adapter might not justify the additional cost of an I/O processor, combining a number of these adapters under a single I/O platform can produce a cost-effective, intelligent solution.
  2. Stackability of Drivers
    Stackability of drivers enables a third party vendor to provide value-added expansion capability, independent of both the OS and hardware. The major enhancement to stackable drivers pioneered by the I2O specifications is the peer-to-peer capability. This moves data between I/O subsystems without impacting the host and without taxing the CPU.
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What are some I2O ready products from TMC?
TMC currently offers the AD6NF9, a dual Pentium Pro motherboard that is designed by implementing the 440FX PCIset and the i960rp RISC as an I2O processor. The board also has IxWorks RTOS (Real Time Operating System), enabling server vendors to build a server system plugging in various I2O enabled add-in cards from companies such as Adaptec, Mylex, QLogic and Symbios Logic.
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