每日科技英文28:DMA(直接内存访问)及DataBus(数据总线)

今日要点:

1. DMA和DataBus定义
2. which做关系副词时介词前置

DMA（直接内存访问）

Direct Memory Access.

A technique for transferring data directly between two peripherals (usually memory and an I/O device) with only minimal intervention by the processor(没有谓语动词，并非是一句句子，这么长的描述只是对technique的解释。).

DMA transfers are managed by a third peripheral called a DMA controller.

直接内存访问。一种直接在两个外设（通常是内存和I/O设备）之间进行数据传输的技术，它只要处理器最少的介入。DMA传输由叫DMA控制器的第三方外设进行管理。

• transfer...between...在...两者之间传输，between表示两者之间

• with only minimal intervention by : 介词短语

Data bus（数据总线）

A set of electrical lines connected to the processor and all of the peripherals with which it communicates.

When the processor wants to read (write) the contents of a memory location or register within a particular peripheral, it sets the address bus pins appropriately and receives (transmits) the contents on the data bus.

连接处理器与所有外设进行通讯的电子线路集。当一个处理器想去写（读）某一特定外设中的存储器地址或寄存器中的内容时，处理器设置地址总线并在数据总线上接收（传输）内容。

今日语法要点:

A set of electrical lines connected to the processor and all of the peripherals with which it communicates.

关于这句句子，我觉得满模糊的。

connected to 到底是动词的过去式作谓语还是过去分词做后置定语修饰A set of electrical lines?

我个人偏向与connected to是过去分词做后置定语

• connected to the processor and all of the peripherals应该是过去分词做后置定语修饰A set of electrical lines，而不是将connected to 理解为谓语

with which其实是状语从句，which做关系副词。

with which it communicates其实是:

which it communicates with.

communicates with为不及物动词，将with前置到which前面，形成with which做关系副词使用，而这里的it指代的是A set of electrical lines 。

讲的比较晕，先就这样子吧。等我查好资料再继续系统的聊一下吧。

这个是其实涉及几个方面的语法知识，例如:

• 及物动词和不及物动词
• which，where,when,how...等这些核心的语法词，到底是做关系副词还是关系代词.