Deciphering Computer Ad Mumbo-Jumbo

Laptop_HPI’ve always really been interested in cars: not the intricate details of how they work, mind you, but more how they look and the cool new features they offer. I understand the appeal of “fine Corinthian leather” and can envy “0 to 60 in 5.2 seconds.” However, if the ads instead focused on things like a “Continuously Variable Transmission”, “Limited Slip Differential”, or a 1.2 GW Flux Capacitor, I wouldn’t be nearly as impressed, because those are beyond my comprehension.

So why do computer sellers throw so many hard-to-understand terms at their customers? They seem to write their advertisements as if customers understand, let alone care, what a 6MB L2 cache is and why it’s a good thing. I suppose printing a litany of esoteric statistics conveys the impression that the customer can buy something NASA engineers would drool over. Honestly, though, I wonder if the lay person has any idea what even a quarter of the typical computer ad means.

Computer advertisers likely won’t be changing their strategy anytime soon. So, I’ll take a few paragraphs now to try to unravel some of the mystery.

Suppose you find an ad that lists the following specs:

  • Intel CoreTM 2 Duo (2.66GHz/1066Mhz FSB/6MB cache)
  • 15.6” High Definition (1080p) LED Backlit LCD Display (1366 x 768)
  • 512 MB ATI Mobility Radeon Graphics
  • 4GB Shared Dual Channel DDR2 at 800MHz
  • 500GB SATA Hard Drive at 5400RPM
  • 8X Slot Load DL DVD+/- RW Drive
  • 802.11 a/g/n and Bluetooth 3.0
  • 85 WHr Lithium Ion Battery
  • 2 USB 2.0
  • HDMI and 15-pin VGA
  • 10/100/1000 Ethernet

Intel CoreTM 2 Duo identifies the central processing unit, or CPU. The CPU is the “brains” of the computer, the component that calls the shots. It consists of a control unit to manage the processing of instructions and an arithmetic-logic unit to do the actual processing. The “CoreTM 2 Duo” part is a marketing name. Still, it indicates that the CPU actually consists of two processors operating in parallel. That means that the machine will be twice as fast as a single-core machine for certain tasks. The speed of the processor is 2.66GHz, which means that it can perform process signals (bits) at a rate of 2.66 billion per second. Obviously, that’s ridiculously fast, but faster processors exist.

The results of the calculations aren’t actually communicated from the processor that fast, however. The circuitry that carries the CPU’s handiwork to the memory is called the front-side bus, or FSB. The FSB is limited in speed by the uncompromising physics of the conducting material. The FSB can carry the signals at only 1066 MHz, or 1,066 million per second. While that sounds really fast, that’s more than 2,000 times slower than the CPU is churning them out. So, it’s like pouring a liquid into a funnel. Just like a funnel has a reservoir, however, so does the CPU. A CPU has a cache that stores the CPU’s output while it’s waiting to hop onto the FSB. There is 6MB worth of space in this machine’s cache, which means that it can store over 6 million bytes worth of waiting data. Without the cache, the CPU would be limited to the lethargy of the FSB, and we’d be experiencing 1995 all over again.

The data travels through the FSB to the memory unit. This machine has 4GB of memory, which means it has over 4 billion cells for holding data. The ad says that the memory is “shared”, which means that both of the CPU’s two cores can access it. “DDR2” is the name of a technology that means “Double Data Rate Version 2”, which suggests that it is twice as fast as older technology memory. The 800MHz figure means that each memory cell can change its contents at a rate of 800 million times per second.

The video capabilities of the computer are described in terms of its resolution and its graphics card. The graphics card is built by ATI as part of its Mobility Radeon line of laptop graphics cards. A graphics card is to graphics what the CPU is to data: it is the brains of the computer’s picture-drawing subsystem. The “video brain” is specially wired to handle the complex mathematics associated with scaling, rotating, and translating graphical images on the screen. The graphics card turns drawing instructions into frames of colored pixels. Each frame occupies the entirety of the video screen. The graphics card stores instructions and frames of animation in its own dedicated memory which, in this case is 512 MB in size. The larger the amount of video memory, the more frames of animation can be stored, and the greater the number of instructions in can store in advance of executing them.

Each frame of video consists of a matrix of tiny square dots called pixels. The frames this computer shows can consist of a maximum of 1366 pixels horizontally and 768 pixels vertically. The larger these dimensions, the smaller the individual pixels are, and so the smoother and less blocky images on the screen will appear. At 1366×768, this machine has a rather good-looking display. That also happens to be the minimum resolution for supporting all features of Windows 8. In fact, if you’re buying a machine with Windows 8, you should not buy a system that has less than this resolution. The laptop also allows you to connect an external monitor, through either VGA (an older video technology) or HDMI, which can pump HD video and sound to an external display.

The ad does have a misleading claim about its high-definition (HD) capabilities. It claims that it shows 1080p HD. The statistic 1080p means that it can show 1080 rows of pixels. This machine’s screen, however, has a maximum resolution of 768 rows of pixels, since it is rated at 1366×768. So, it actually has to compress the 1080 rows of pixels in an HD signal down to 768, which means that it’s not truly HD. Sometimes advertisers are more interested in packing lots of impressive-sounding features into their adds instead of being completely faithful to what the claims actually mean.

The hard drive, which stores data when you turn the machine off, has a capacity of 500GB. That means it can hold about 160,000 high quality digital photos. That is more than enough space for most people. SATA is just the name of the type of connection that links the hard drive to the rest of the system. Almost all computers today use SATA, so this isn’t a distinguishing feature of the machine. A hard drive is an electromechanical device that stores data on a magnetic rotating platter. The drive has to rotate very fast to keep pace with the rate at which data can be deposited on it. It can’t possibly keep up because it is mechanical, and mechanical processes are always much slower than electrical ones. So, the faster the rotational speed, the better. This particular machine has a drive that rotates at 5,400 RPM, which is actually a bit on the slow side but is typical of today’s laptops. A 7,200 RPM drive would be a lot better. Better yet would be a solid-state drive (SSD), which replaces the mechanical processes with electronic ones and would provide amazing improvements in performance. SSD drives are comparatively small, however, and they’re also very expensive compared with conventional hard drives. Still, I have an SSD in my laptop, and I’m never going to go back to a conventional drive unless someone promises to cure my baldness for me.

The optical drive in this computer is a rewritable DVD drive. The “8X” part of its description indicates that it can write data at 8 times the rate at which it can play it back. The “DL” designation means “double layer”. In other words, this drive writes twice as much data per unit area than a single-layer DVD would, which means that it can pack 8.5GB onto a disk rather than the standard 4.7GB. The confusing “+/-RW” descriptor confounds just about everybody who tries to make sense of it. It simply means that it can record and re-record data on a DVD that is likewise marked “+/-“.

The wireless card of this laptop is compatible with the standard Wi-Fi signals currently broadcast by wireless network routers. The Wi-Fi standard is called 802.11, and there are three variants: a, g, and n. The only one that matters is variant n, which is the newest, fastest, and longest-range version. This laptop can also connect using the previous generation of Bluetooth, a short-range radio communication technology that can link the laptop to speakers, microphones, cell phones, and other compatible devices. (The newest Bluetooth is version 4.0, but version 3.0 is certainly adequate.) For wired connections, the laptop can communicate at a rate of 1 gigabit per second, or about 1 billion signals (bits) per second, which is the limit of what wired local networks can support today.  Finally, the laptop also has 2 USB 2.0 ports. USB stands for “Universal Serial Bus”, and version 2.0 pumps out data at a rate of over 480 million bits per second. Newer and more expensive laptops have at least one USB 3.0 port, which can communicate at an astounding 5 billion bits per second.

The laptop provides all these features either plugged in or running off its battery. The battery is made of Lithium Ion, the common type found in laptops and other rechargeable appliances today. It can provide 85 watts of power for an hour before running out. This system might consume 85 watts of power for short periods of time, particularly if you are watching a movie, playing a game, doing a lot of calculations, and writing a bunch of data to disk simultaneously. Most of the time, though, the laptop will be consuming far less than this, perhaps a quarter of its peak. So, the battery should be able to power the device for a about three or four hours, depending on what it is being asked to do.

All in all, this is a moderately capable laptop that would probably fetch about $400 at Best Buy. Now, hopefully, you can hand over that amount of cash knowing a little bit more about what it is you’re actually buying. Perhaps you’ll even be able to save a few bucks so you can buy a fine Corinthian leather case to put it in.

 

About Ray Klump

Professor and chair of Mathematics and Computer Science Director, Master of Science in Information Security Lewis University http://online.lewisu.edu/ms-information-security.asp, http://online.lewisu.edu/resource/engineering-technology/articles.asp, http://cs.lewisu.edu. You can find him on Google+.

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