The pieces of equipment making up the computer system are known as
hardware. The most important item of hardware is the CPU (Central
Processing Unit). This is the electronic unit at the centre of the
computer system. It contains the processor and the main memory.
You can look at what interpretation is most likely.. and it's far more likely that by It, it doesn't mean processor. It's absurd to think it does. It's ridiculous to interpret it the way you have and say it's wrong.
For example, if you think that by CPU it means processor, / that "it" means processor, then it'd be saying that the processor contains a processor. Or, the other absurd interpretation you come up with, that the processor contains main memory (it doesn't).
One consideration is this -
Well, there are two different definitions of CPU. An old fashioned one that I saw in British A-Level Computing textbooks when I last checked some in 1998-2000, that defined CPU as the computer case. The box. Most people are very unfamiliar with that definition of CPU. Or with that ever being a definition of CPU. And even many people that have been in computing for a long time are unfamiliar with that definition. Note- commenter "Class Stacker" who is probably based in America, has seen definition used in the past too, and also on international projects he has worked on.
And the definition that people are more familiar with nowadays, which is CPU as processor.
Another consideration is this. The "It" in the last sentence.
It contains the processor and the main memory.
What is "It" referring to. Does it mean, not even CPU, but the Computer System, in which case, yes, that's true.
Does it mean CPU in the now unusual sense, of the box, a definition common in some books i've seen in the UK about 15 years ago. Yes that's true. So, CPU in the sense of the box.. Then Yes, that's true.
But if "it" refers to processor, or CPU in the sense of processor, then no, that's not true.
She rejected my point about that author probably meant CPU cache, and
clarified that main memory is RAM. She neither accepted that he's
probably wrong in that case.
She's right that Main memory is RAM, and you were wrong not to agree with her on that - that main memory is RAM. (if main memory isn't RAM then there is a very subtle difference), and anyhow, most people don't use the phrase "main memory" much anymore anyway. CPU can contain memory, storage locations, known as registers, which are distinct from the storage locations in RAM/main memory.
Everything hinges on what is referred to by the "It" of that last sentence. Also i'd be interested in what the textbook is. Title, author, year.
The text didn't say the CPU did, it said "It", but let's say "It" meant CPU. You ask "is it correct to say that CPU contains RAM? Or did it at any point in any form?" Yes it is correct, under a definition of CPU that is old (and maybe UK based), and that most people aren't familiar with! But in terms of choosing definitions that are accepted and agreed upon by people, in this interconnected age of the internet, modern times, no, CPU should really just be defined as processor because it's easier that way and people get confused otherwise. But certainly from time to time the old definition of CPU pops up.
But as for what that text means, it is clearly using the old definition of CPU. It's not saying the processor contains a processor, that's absurd. And therefore it's also clearly not saying the processor contains ram.
The CPU is the processor chip. It contains some random-access memory, used mainly for caching. In a PC the main memory is in separate chip-sets, in other locations on the motherboard. However, over the years some processors have been produced with limited on-chip main memory, for use in self-contained units, such as process controllers; they are too limited for use in PCs. However, occasionally the term CPU is misapplied to complete systems, particularly in network diagrams, as a generic term for processing nodes (PCs, tablets, etc), to distinguish them from other networking components. – AFH – 2017-04-09T14:32:14.707
2The text is simply a bit outdated and/or takes a higher level perspective on computers. Today, the word CPU is used for a chip which does not contain RAM (the microprocessor). But in the olden days, and also from a conceptual view (think mainframes or big data centers), the CPU was simply distinguished from the periphery (both very huge boxes). I'm not sure the term "CPU" is still used this way in any context, but is definitely was, until the modularity of computers changed. In this regard, I beg to differ from the comment and answer given so far. – Run CMD – 2017-04-09T15:31:46.230
@ClassStacker So you've seen that usage in the past too.. I have seen that usage in the UK in the past. Are you based in America? – barlop – 2017-04-09T16:54:47.057
Show her separate CPU chip and RAM stick. – Oleg V. Volkov – 2017-04-09T16:56:15.650
@ClassStacker, uh, so it not only USSR grandma's who call PC case with everything inside "processor". That's kind of surprising... – Oleg V. Volkov – 2017-04-09T16:57:44.583
@barlop I've worked with computers with a CPU the size of closets and hard disks the size of a washing machine, being able to store unimpressive amounts of data. And I had to deal with COCOM aspects in international projects.
– Run CMD – 2017-04-09T17:02:07.403@OlegV.Volkov No worries, I'm not taking that personal. – Run CMD – 2017-04-09T17:03:18.043
@OlegV.Volkov No, Oleg. I'm talking about an old usage of calling the PC case a CPU, not calling it a processor. – barlop – 2017-04-09T17:03:48.617
@ClassStacker I see that includes america. And are you in america? Why are so many americans ignorant of this? – barlop – 2017-04-09T17:05:24.173
@OlegV.Volkov She knows that it's two separate parts. As I remember explanation was that in English by saying CPU people refer to CPU and RAM combination, because they're pretty useless on their own. I wonder where is motherboard then... – mushi.f – 2017-04-09T20:15:30.550
"people refer to CPU and RAM combination, because they're pretty useless on their own" -- That's lame reasoning; you could start extending that to a graphics card and HDD. Of course then you end up with the ignorant user's conflation of CPU and computer. From my experience, which probably goes back as far as @ClassStacker, there has never been any change in the proper or technical definition of "CPU". However I have seen poorly-informed users (and even engineers and developers) incorrectly refer to a SoC (e.g. micro-controllers and "computer on a chip") as a "CPU". – sawdust – 2017-04-10T01:28:04.410
@mushi.f That explanation about things being useless on their own, is ridiculous and makes no sense. Even a computer is useless on its own without a user, but that doesn't mean we include the user in the term Computer. Obviously individual components have names too. Nevertheless, in the old broad definition for CPU(that's the definition as used in your text, as jll's answer has indicated), includes motherboard, everything plugged into the motherboard, and even the case. The things "other" to the CPU(in that definition), are Peripherals i.e. keyboard, mouse, monitor, printer. . – barlop – 2017-04-12T19:23:18.730