The serial RAM model.串行內存模型
There is a single serial processor connected to memory. This processor issues instructions that operate on data. The operands of these instructions always live in memory.
When you analyze the cost of a serial RAM algorithm, you assume that all instructions have a cost that is bounded by some constant. Now from thar starting point,you do a big O style analysis in terms of the input size. So,that is the serial ram model.
有一個單一的串行處理器連接到內存,這個處理器發出操作數據的指令,這些指令的操作數總是存儲在內存中.
當你分析一個串行RAM算法的cost時,假設所有指令的成本都是有限的常數級。現在從這個起點開始，針對輸入大小進行一個大O分析。這就是串行內存模型。
What are the alternatives to the serial RAM model?串行RAM模型的替代方案是什麼?
The parallel RAM or PRAM model. 並行RAM或PRAM模型.
Instead of one processor,there may be many.They all see the same memory,and you still assume a bounded constant cost per operation. But you get to work with more than one processor.
有多個處理器,它們都看到相同的內存，但仍然假設每個操作的固定cost是有限的常數級,但可以使用多個處理器一起工作。
And since the processors all see the same memory, they can coordinate and communicate by modifying shared variables.
由於處理器都看到相同的內存，所以它們可以通過修改共享變量來進行協調和通信。
Now in this model,your algorithmic analysis will involve big O as before.but you will try to reduce the total cost by up to a factor of P.
在這個模型中，你的算法分析會像以前一樣涉及到大O,但要試着將cos降低P倍.
