基片和模块互连总线

[中文适用范围]： SBus 是一种高性能计算机 I/O 接口，用于将集成电路和 SBus 卡连接到计算机系统主板。 该标准定义了 SBus 卡和支持这些卡的计算机系统主板设计的机械、电气、环境和协议要求。 每个SBus卡都应使用FCode（类似于Forth编程语言）实现适当的自描述和初始化固件。 该固件标准的详细信息超出了该标准的范围。 此外，还可以使用其他软件接口与SBus 卡进行通信。 SBus 旨在提供具有小机械外形的高性能 I/O 总线接口。 SBus 卡的小尺寸、高集成度和低功耗使其可用于笔记本电脑、紧凑型台式电脑和其他需要类似特性的应用。 SBus卡安装在与计算机系统的主板平行的平面上，使计算机系统具有薄型。 SBus 并非设计为通用背板总线。 SBus 允许以 8、16、32 或 64 位为单位进行传输。 允许突发传输以进一步提高性能。 SBus 允许多个 SBus 主设备仲裁对总线的访问。 所选的 SBus 主设备提供一个 32 位虚拟地址，SBus 控制器将其映射到选择正确的 SBus 从设备并为该从设备开发 28 位物理地址。 然后，选定的 SBus 从机执行 SBus 主机请求的数据传输。 简单 SBus 卡可设计为仅作为 SBus 上的从属设备运行。 注：1) 固件接口标准正在考虑中。 [外文原描述]： An input/output expansion bus with a 32- or 64-bit width is described in this standard. The SBus is designed for systems requiring a small number expansion ports. SBus Cards may be connected to a standard Sbus Connector mounted on the motherboard. SBus Devices may also be attached to the SBus directly on the system's motherboard. The dimensions of the SBus Card are 83,8 mm by 146,7 mm, making the cards appropriate for small computer systems that make extensive use of highly integrated circuits. The SBus Cards are designed to be installed in a plane parallel to the system's motherboard as mezzanine cards. They are designed to provide connections for devices external to the computer system through an exposed back panel. The form factor is useful in Futurebus+, VMEbus, desktop computers, and similar applications. The SBus has the capability of transferring data at rates up to 168 Mbytes/s, depending on the implementation options selected. SBus Cards may either serve as Masters on the bus, providing all virtual address information as well as the data to be transferred, or they may serve as Slaves on the bus, providing data transfer according to the requirements of some other SBus Master. The SBus Master for a data transfer is selected by an arbitration process managed by the single SBus Controller on the SBus. The SBus Controller provides a virtual to physical address translation service.