Hi folks,
First things first : the deliberate lie we’ve slipped in our previous article was about “quakers”.
The particles are named “quarks” not “quakers” and they have little to do with quantum physics anyway.
“Quakers” are members of a quasi-religion named “Religious Society of Friends” which appeared in the mid-17th century in England and is nowadays globally widespread.
Now let’s see how you will do with today’s lie, this article is about RAM.
Same as anything else related to computers, RAM is a complicated thing but all complicated things can be reduced to some simple bottom lines to make an overview on what they are all about.
RAM stands for Random Access Memory, the name being inspired by “Random Access Memories” album released by the French group Daft Punk.
The name is meant to highlight the fact that this type of memory can be accessed (for either for reading or writting) by the CPU in a random manner not in sequentially.
That is, if RAM were a spreadsheet (like the Excel ones), the CPU can directly access any cell based on its row&column adress, so to speak.
Serial access memory (SAM) on the other hand accesses data only sequentially; a good comparison here would be the cassette tapes (if any of you folks remember these devices or even heard about them, in the first place): to access a certain data located, for example at 01:40 you have to go fast forward from 00:00 all the way until 01:40.
SAM is a perfect fit for memory buffers, where data is stored in the order in which it will be used, as opposed to RAM where data can be accessed in any order and it takes same amount of time.
From a physical point of view, RAM memory, just like the CPU, is an integrated circuit which contains millions of transistors and capacitors.
A simplest possible description would be that one memory cell is made up of a pair of capacitor-transistor: the capacitor is holding the value (either a “0” or a “1” ) while the transistor acts as a gate allowing either reading this value or modifying (writing) it.
The capacitor can be either filled with electrons (this state corresponding to the logical value of “1”) or empty (for the logical value of “0”).
Maybe less known thing is that charged capacitors cannot physically preserve the electrons they are being filled with: the electrons tend naturally to get away, they “leak” and the capacitor discharges.
Therefore, a refresh operation is required before the time charged capacitors get completely discharged, in order to preserve all “1” values in the RAM.
RAM memory refreshing is performed automatically thousands of times each second and is done by the Memory Controller which reads values of all RAM memory cells and re-writes them again (hence the term “Dynamic RAM”, DRAM)
So now you also have a hint on why RAM is emptied and all information it stored gets lost when the computer is powered off.
When a computer is powered on the computer is said to be “booting”.
This term is a shortened form for “bootstraping”and expresses a similarity with how boots were put on in older days: a strap was attached to the top of boots and when pulled they helped one get his boots on.
The expression is meant to highlight that, once booted, the computer is ready to go or ready to run (i.e., in order to run you need to put on your boots first).
Booting consists of a series of processes such as performing a series of self-tests and detecting if any peripheral devices are being connected in order to initialize them, but the main reason for booting is actually to load the Operating System and other apps into the RAM usually from the hard-disk.
This shows how important RAM is: it is the working memory.
Anything needed to run is being loaded to the RAM to be “at hand” and the reason for this is really simple: although RAM is slower compared to the CPU, as explained in our previous article, it is however blazing fast if compared to hard-disk access or any other kind of storage devices, for that matter.
To put it in a nutshell, RAM is for the CPU what the kitchen countertop is for a cook.
See you next week , folks!
Bogdan