Articles: A primer on Random Access Memory (RAM)
This scope of this article is to explain RAM– Random Access Memory– and how that might affect your choices when it comes to buying a Mac from us, whether new or used. While meant to be informative, this is far from an exhaustive look at the subject and is designed to build vocabulary and acumen around the subject with out having to become an expert.
A human’s ability to remember and store information for long periods of time (with enough caffeine and head scratching) and still be referenced at a moments notice is an ability very few animals possess. We can remember the name of a new acquaintance while still remembering the names of childhood friends. We can keep a complex idea in mind while working on a different task.
Computers also have short and long term memory storage capabilities, very much like humans.
Keeping with the analogy, things that are “remembered,” such as growing up (settings), going through school (installations and updates), fun events (photos) or your favorite songs (iTunes) are kept in long term memory. A computer’s long term memory component is the hard drive.
Short term memory usually refers to things you are “remembering right now,” such as chores, the next meeting you have, a person's name you just met, a task or group of tasks, or random thoughts that you think about for a split second. Some would argue these types of memories are easily forgotten. While many parts of our brains are responsible for short term memory, in a computer, the Random Access Memory module is the component used for this purpose.
A RAM module is a collection of short term memory chips attached to a small circuit board that work together to temporarily hold data. RAM is also commonly referred to as memory, or memory module. Unlike a hard drive, any data that finds itself inside a RAM chip is volatile, meaning if the power were to go out, any data only in RAM will be lost. The best defense against data loss for most computer users is frequent saving of any work in progress, as this action commits the information to the non-volatile storage: the hard drive.
While the physical form of memory can differ in size and speed, the quantity of bytes that a module can contain is usually what matters most. There are still a few Macs in production that allow the memory to be upgraded, but the majority of Mac computers have RAM integrated into the Main Logic Board, unable to be upgraded or replaced without major repair work.
Mac computers made today tend to ship with 4GB of RAM, and in some cases can be configured with over 64GB. Generally speaking, the more RAM a computer has, the better. Certainly having more RAM than the operating system requires is one of the most important considerations to make when buying a computer.
Mac OS X 10.11 El Capitan requires a minimum of 2GB of ram for the operating system to function. As a rough guideline, having at least double the required amount is ideal for “good” performance. Customers seeking better performance in multitasking, using multiple apps at once, or working with very large video or photo files should consider using 4 or 8 times the required memory.
Here's a nice YouTube video that uses Legos to illustrate how RAM works.
While more memory doesn't make a Mac faster in a speed sense, it will take less time to accomplish tasks if the computer doesn't have to wait for available space in memory to put new data or temporarily hold large files.
For your reference, here is a chart of Mac OS Operating systems and the minimum memory requirement.
By Ian Burnett, Certified Apple Technician