- Your standard desktop sticks are the bread and butter of what makes RAM work. But there's a lot of exceptions to that. So, I wanna talk about what I'm gonna call weird RAM. Now, all of these are different aspects of RAM that are covered on the CompTIA A+, most of which I agree with completely. But one in particular, and the one I'm gonna mention at first, is, kind of, a long-dead RAM, but it's on the test, so I'm gonna talk about it. And that RAM is called RAMBUS. What you have in front of you are old sticks of RAMBUS.
RAMBUS is pretty much long gone. I haven't seen it in many, many years. RAMBUS came out about the time that SDRAM had been out for a while. Now, it was actually the first double-pumped RAM, although DDR SDRAM quickly supplanted it, because RAMBUS wanted money for everybody who made any of this RAM. So, what we're looking at here is a standard RAMBUS, what it was called a RIMM, and R-I-M-M didn't stand for anything, it just sounded like DIMM, so they used the same term.
It's 184-pin RIMM, and you'll notice it has two notches in it, so it's, you'd never confuse it with any other type of memory. The trick to this type of memory is that you had to install it in two's. So, whenever you installed RAMBUS RAM, you always had to put two of these in. And if there were any leftover sockets, you had to put this guy in. This is called a CRIMM. It's not memory, it's just a terminator. So, if you had a RAMBUS motherboard, every slot on the motherboard was populated with something at all times, which is not necessarily the case today.
Now, that is RAMBUS, and take a look at this picture, cause it's probably the last time you're ever gonna see it. But there is another type of RAM. Now, I'm gonna use RAMBUS as an example here, but it's not unique to RAMBUS. Almost any type of RAM has this. And what I wanna do is look at this. I'm gonna flip it over. There are memory on chips on both sides of this stick. If you take a look at this guy, you'll see it's blank. And that's usually the more common thing. We call this single-sided RAM. Now, here's a more common stick.
Let's get this old RAMBUS outta here. So, here's a more common stick. But it's also double-sided memory. And let me pull one more out. Take a look at this guy. He's double-sided also. Double-sided memory's great. It's really, really popular. The secret is, though, is that you've gotta have a motherboard that supports it. So, don't go buying double-sided memory until you're sure, by reading your motherboard book, that your system can handle double-sided memory. Now, there is another type of weird memory I wanna talk about, and that's called ECC or Parity memory.
ECC or Parity memory is memory that has extra chips that are designed for error correction. So, these types of RAM, they look like regular RAM, you can't tell by looking at them that they're different. But the important thing to appreciate is that these types of RAM can only be used on motherboards that accept this type of RAM. So, you can't go out and buy ECC RAM and put it into a motherboard that doesn't know what it is. Usually, you're only gonna see this type of RAM on big server systems and stuff like that. In general, you will almost never see Parity, or much better known today as ECC memory, on a common desktop or a laptop, or anything like that.
Speaking of laptops, I guess we oughta talk about one of my old faves right here, and this is an SODIMM. SODIMMs are invented for laptops more than anything else. They're the same thing, they're SDRAM, DDR, DDR2, DDR3. They've got all the speeds that you know and love from regular desktop memory. You have the capacities, although SODIMM, simply because of their physical size, tend to be slightly lower capacity, but other than that, SODIMMs are just regular, old, good, old RAM of the same types discussed in other episodes.
The trick SO memory is that you have to make sure you have the right size for your laptop. Your traditional sizes have always been pretty much 100, 144, and 200 pin. Now, the thing is, is unlike desktop memory, you can have DDR, for example, in 100, 144, and 200 pin sizes. So, I can't just sit here and tell you that all DDR3 is gonna be a particular size of SODIMM, for example. Well, actually I can in one aspect. I wanna mention a fourth size of SODIMM, which is the 204 pin SODIMM.
204 pin SODIMMs are pretty much unique to DDR3. The trick with using any type of laptop memory like this is to grab your laptop and make sure that you're buying the right type of memory for your system. Keep in mind, there's a lot of weird memory out there. I've just touched on the stuff that you're gonna be seeing on the A+ exam, but there's other things to watch out for. For example, low-latency memory, or high-density memory, things like this. You're not gonna run into these buying these at your regular stores.
It's usually that guy in the back of a white van who's trying to sell you some RAM on the cheap. And those are the things you have to avoid. And that's another big thing for me when it comes to RAM, I always buy brand-name stuff. (upbeat instrumental music)
The CompTIA A+ 220-901 exam is comprised of six key parts. The first, core processing, is covered by this course. Instructor Mike Meyers explains the fundamentals of PCs, microprocessors, RAM, and BIOS. He also shows you how to set up, connect, maintain, and troubleshoot the main components of a computer.
Note: The six courses designed for the CompTIA A+ (220-901) exam preparation include core processing, core hardware, peripherals and building a PC, displays and printers, networking, and laptops and mobile devices.
We are now a CompTIA Content Publishing Partner. As such, we are able to offer CompTIA exam vouchers at a 10% discount. For more information on how to obtain this discount, please download these PDF instructions.
- How do personal computers (PCs) work?
- What is a central processing unit (CPU)?
- When is random access memory (RAM) used?
- What is a basic input/output system (BIOS)?
- Installing a CPU
- Working with extensions and sockets
- Troubleshooting RAM
- Setting up a BIOS