Basically, the operation code tells the ALU what operation to perform.

基本上，操作代码告诉 ALU 执行什么操作。

We’re going to use this ALU when we construct our CPU two episodes from now.

从现在起两集构建 CPU 时，我们将使用这个 ALU。

ALUs also output a series of Flags, which are 1-bit outputs for particular states and statuses.

ALU 还输出一系列 Flags，这些 Flags 是特定状态和状态的 1 位输出。

When you understand an ALU’s design and function, you’ll understand a fundamental part of modern computers.

了解 ALU 的设计和功能后，您就会了解现代计算机的基本组成部分。

Our 8-bit ALU has two inputs, A and B, each with 8 bits.

我们的 8 位 ALU 有两个输入，A 和 B，每个输入有 8 位。

Which brings us back to that ALU you admired so much at the beginning of the episode.

这让我们回到了剧集开始时您非常钦佩的那个 ALU。

It also enables Register A and feeds it into the second ALU input.

它还启用寄存器 A 并将其馈送到第二个 ALU 输入。

That's because simple ALUs don’t have a circuit for this, and instead just perform a series of additions.

这是因为简单的ALU没有用于此的电路，而只是执行一系列加法。

For example, many processors will have four, eight or more identical ALUs, so they can execute many mathematical instructions all in parallel!

例如，许多处理器会有四个、八个或更多相同的 ALU，因此它们可以并行执行许多数学指令！

So far, for most of this series, we've focused on hardware -- the physical components of computing -- things like: electricity and circuits, registers and RAM, ALUs and CPUs.

到目前为止，对于本系列的大部分内容，我们都专注于硬件——计算的物理组件——比如：电力和电路、寄存器和 RAM、ALU 和 CPU。

So today we’re going to take those Boolean logic gates we learned about last week to build a simple ALU circuit with much of the same functionality as the 74181.

因此，今天我们将采用上周学习的那些布尔逻辑门来构建一个简单的 ALU 电路，其功能与 74181 的大部分功能相同。

Our 8-bit ALU has two inputs, A and B, each with 8 bits. We also need a way to specify what operation the ALU should perform, for example, addition or subtraction.

我们的 8 位 ALU 有两个输入， A 和 B， 每个输入有 8 位。 我们还需要一种方法来指定 ALU 应该执行什么操作，例如加法或减法。

When you understand an ALU’s design and function, you’ll understand a fundamental part of modern computers. It is THE thing that does all of the computation in a computer, so basically everything uses it.

了解 ALU 的设计和功能后， 您就会了解现代计算机的基本组成部分。 它是在计算机中完成所有计算的东西，所以基本上所有东西都使用它。

Unlike the 8-bit ALU we made today, the 74181 could only handle 4-bit inputs, which means YOU BUILT AN ALU THAT’S LIKE TWICE AS GOOD AS THAT SUPER FAMOUS ONE. WITH YOUR MIND! Well.. sort of.

与我们今天制作的 8 位 ALU 不同， 74181 只能处理 4 位输入，这意味着您构建的 ALU 是超级著名 ALU 的两倍。 用你的思想！ 好吧. . 有点。

Unlike the 8-bit ALU we made today, the 74181 could only handle 4-bit inputs, which means YOU BUILT AN ALU THAT’S LIKE TWICE AS GOOD AS THAT SUPER FAMOUS ONE. WITH YOUR MIND!

与我们今天制作的 8 位 ALU 不同，74181 只能处理 4 位输入，这意味着您构建的 ALU 是超级著名 ALU 的两倍。用你的思想！

Of course, this extra circuitry makes the ALU bigger and more complicated to design, but also more capable - a complexity-for-speed tradeoff that has been made many times in computing history.

当然，这个额外的电路使 ALU 更大，设计起来更复杂，但也更强大 - 在计算历史上已经多次进行复杂性与速度的权衡。

When it was released in 1970, it was It was the first complete ALU that fit entirely inside of a single chip - Which was a huge engineering feat at the time.

当它于 1970 年发布时，它是第一个完全适合单个芯片内部的完整 ALU - 这在当时是一项巨大的工程壮举。