http://pinouts.ru/connector/index_conn_2_6.shtml Ports & Connectors The various connectors and ports on the computer allow it to communicate with the many different devices and peripherals attached. Because there are so many cables and cords attached to the back of the computer, and so many different types of connectors, it often seems a little intimidating to the newer user. Although there are some devices which may use the same connector or port, the individual devices and their cords can only physically attach to one certain type of connector; so don't feel nervous about hooking your system together. There's really no way you can do any harm to your computer just by hooking it up, as long as you follow a few common sense rules: The first thing to know is the difference between a male and female connector. The male connector fits inside the female connector. If the connector has pins protruding from it, its a male connector. If the connector has holes for the pins to fit into, then its a female connector. When you hook something up to your computer, the male and female connectors are hooked together. The connectors on the back of your computer are called input/output ports (i/o ports) or communication ports. The second thing you should remember is that when you join a connector to a port, they must have the same shape and the same number of pins or holes. In other words, a square peg won't fit into a round hole, and its not wise to try to jam fifteen pins into nine holes (part of the 'common sense' thing I was talking about).Which brings us to another very important point, never force anything. Here's one that's hard to do. Always make sure the computer is off before attaching connectors or cables to any of the ports. This can cause little power gliches (another technical word) that could corrupt an open file or cause a program to freeze. It can even cause a small short that could damage or ruin components inside your computer. I know, you've done it a hundred times and never had a problem. Well, that's good. If you want to continue to practice risk management, that's your perogitive, but be aware of the possibilities and don't be surprised when you finally get burned. USB ports are the only ports that should be considered hot-swappable (this means they can be plugged in or unplugged while the machine is on). Only one more thing to remember. There are small hexagonal nuts on either side of many of the ports on your computer. These allow you to screw the connectors in so they don't accidentally fall out or loosen. They just have to be screwed down, they do not have to be tightened. These nuts are actually the heads of small bolts that pass through the back plate on your computer and are attached with a small nut on the other side. If you tighten the screws too much, then when they're undone, they may take the bolt with them and the small nut may fall off inside the computer (onto the motherboard or an expansion card). Not a good thing. Ports & Connectors (continued...) Now that we know the basic rules, let's take a look at some of the connectors or ports you might find on your computer. DB Connector The most common connector is the DB connector. It's sort of a 'D' shape and is sometimes called a D-shell connector (go figure). It's designated as DB-x, with 'x' being the number of pins or holes on the individual connector. So a DB-9 female connector would be a 'D' shaped connector with 9 holes. This would receive a cord with a DB-9 male connector (with 9 pins). If you find a DB male connector port on the back of your computer, (either a DB-9 male or a DB-25 male) it's going to be a serial port. Serial ports are also called COM ports or RS-232 ports (Reference Standard #232 as referenced by IEEE*). Serial ports transmit data one bit at a time and are relatively slow compared to other ports. However, they are plenty fast enough for some external devices such as a mouse, or an external modem. Because only one bit at a time is passed along a serial cable, it can travel a fair distance before data integrity is challenged (or errors start to occur). A serial cable shouldn't be more than 50 feet in length. Incidentally, in case you were wondering, if you have a device with only nine holes on its connector, and only a DB-25 male serial port to connect to, all you need is a 9 to 25 pin adapter. There's no difference between a 25-pin serial port and a 9-pin serial port other than the fact that the DB-25 male has sixteen extra pins that it doesn't use. If you have an older computer, and see a DB-9 female connector on the back, it's probably a video connector for an older EGA or CGA monitor. My guess is that you won't see one on your computer. However, if the question should ever come up, it could also be a Token Ring network adapter port. Look on the back of your computer, you may be able to find two different DB-15 female connectors. If you see three rows of five holes, then it's your VGA or SVGA video monitor adapter. If you see only two rows (one of eight holes and one of seven), then it's probably a joystick adapter. A DB-25 female connector on the back of your computer is going to be a parallel port. Parallel ports can transmit data eight bits at a time which creates a noticeable speed increase over serial ports. Most commonly used as printer connections, several other devices now use the parallel port such as tape backup systems, Zip drives and scanners to name a few. These devices are generally fitted with what is referred to as a pass-through port. This means that you can hook up your scanner to the parallel port (DB-25 female) and then connect your printer to the DB-25 connector on the back of the scanner and have access to both devices. This usually works well but does pose some problems. First off, the device has to be turned on for the pass-through port to work. To take this one step further, the device often has to be turned on before the computer is booted, to be recognized properly and for the right drivers to be loaded at startup. Also, users tend to think that they can daisy-chain these devices. In other words, connect their scanner to the computer, attach their Zip drive to the back of the scanner, their tape drive to the back of the Zip drive, and then their printer to the pass-through port on the back of the tape drive. Believe it or not, I've seen this done and I've seen it work (more or less). I've also seen it work one day and not the next. It's a hit and miss sort of thing (more miss than hit) and I wouldn't trust the integrity of the data past the second device. Another thing to keep in mind, is that the cable on a parallel device shouldn't be more than 10 feet long. Data errors can occur beyond this distance. DIN Connector The DIN connector is a small round connector, usually with a keyed slot for proper orientation. Again, it's designated as DIN-x, with 'x' representing the number of holes or pins on the connector. It comes in a couple of different sizes and it's been used on computers about as long as the DB connector has. It's a fairly popular connector because of its small size and solid connection. The most common DIN connector would have to be the DIN-5 keyboard connector. Its the largest of the DIN connectors that you're going to find on your computer and its been around for a long time. If you own a newer computer, then the DIN-5 has probably been replaced with a DIN-6 (mini-DIN or PS/2) connector. The PS/2, or DIN-6 connector, was mainly used by Macintosh computers for the longest time (Macintosh also used a DIN-8 connector for their printer). You may hear them referred to as a mini DIN-6 connector. They're smaller and more compact than the typical DIN-5 connector and have become the standard for both the keyboard and the mouse on newer PCs. If this is the case on your computer, then the two DIN-6 female ports on the back of your computer are going to look an awful lot alike, and you need to distinguish between the mouse port and the keyboard port before hooking them up. They may be color coded or they may have a little icon beside them representing their use. Whatever the case, you're not going to do any harm if you accidentally get these two devices switched. Your mouse won't work, or you'll get a keyboard error at boot up. Your first course of action for troubleshooting this type of problem should be to check the connection anyway.