PC mouse connector types

The last several vintage computer mice I’ve bought on Ebay were not properly described. So I figured I would write this guide because it will help people find the right mouse for a computer, and if you are trying to sell one on Ebay, properly describing the mouse connector type will help you sell it more quickly, and potentially get more money.

USB

USB needs little introduction. It is the most common connector type today, and probably the most familiar. It uses a rectangular metalized plug and in the case of USB 1.1 or 2.0, it only plugs in one direction. The newer USB 3.0 can plug in either direction, but that connector is not as common on a mouse as the older connector type. This is the same USB you use for most peripherals today.

PS/2

Another common connection type is PS/2, so named because it was introduced with the IBM PS/2 in 1987. It uses a round mini DIN connector with eight pins and a rectangular peg in the middle. The rectangular peg helps to distinguish it from a bus mouse.

This connector type was very common in the 1990s and into the early 21st century.

Here is a tip with PS/2 mice: always list the brand name on the mouse. Sometimes people will be looking for a mouse that matches a specific computer, so if you have the brand someone happens to be looking for, listing the brand will make it easier for them to find you rather than scrolling through hundreds of other listings. For example, an AST-branded PS/2 mouse that would just be a spare part to me is worth more to someone who owns a vintage AST computer. Someone restoring an AST computer will willingly pay $10-$15 for one.

Serial mouse

Yes, the “S” in USB stands for serial, but long before there was USB, there was another standard for serial called RS-232. The most common variant of this connector is a nine-pin d-sub connector commonly called DB9, although the proper name for it is DE9. If there is room in your listing, it doesn’t hurt to mention both, since people may search for either.

Crucially, a DB9 serial connector has holes in it rather than pins. It is a female connector. A male DE9 connector with pins is actually a type of bus mouse connection, and very uncommon. We’ll get to bus mice in the next section.

The DB25 RS-232 serial connector for PC mice

The other type of RS-232 mouse uses a 25-pin connection. This connector was going out of fashion when mice started to become popular, so it is not terribly common on mice. A cheap and simple adapter converts between the two sizes, so the 25 pin connector is not a showstopper. But listing it properly as a 25-pin serial mouse will cut down on confusion.

RS-232 mice were common in the 1980s and into the mid 1990s.

Non-PC mice with a 9-pin connector

The other thing to watch for with the nine pin connector is that Apple, Atari, and Commodore all used a 9-pin connector on their computers as well that looks like a serial mouse connector. And exactly none of those were compatible with PC mice.

Spotting an Apple, Atari, or Commodore mouse is straightforward enough. Their brand name will be on the underside and their logo may be on the top. The Amiga tank mouse has no logo on the top but has a Commodore label on the underside. But if you have a third-party mouse, look it over before you try to sell it as a PC mouse. A telltale sign of a third party mouse compatible with Atari or Commodore is a sliding switch on the underside. Many of those will have a sliding switch to toggle between Atari and Amiga, because the two were very similar and only needed a simple wiring change to make them compatible.

Don’t write these off. All of these computer types have a following and mice for them aren’t easy to find. Properly identified, they’ll sell.

Bus mouse

The bus mouse, sometimes also called an Inport mouse, is probably the most confusing type. Most bus or import mice used a nine-pin DIN connector. This looks a lot like the PS/2 connector, but it does not have the plastic peg in the middle. If the connector has a plastic peg, it is not a bus mouse.

The bus mouse was a different type of connector that typically used its own interface card, although some graphics cards included a bus connector. On early PCs that didn’t necessarily have two RS-232 ports, a bus mouse bundled with a card provided a convenient solution. Microsoft and Logitech were the two largest manufacturers of this type of mouse, but not the only ones. Bus mice gave way to RS-232 and PS/2 as PCs started more commonly including two 9-pin RS-232 ports, sometimes in addition to a PS/2 mouse port.

Early DE9 PC bus mice

The earliest examples of the bus mouse used a DE9 or DB9 connector with pins. It is very easy to mistake this for a 9-pin RS-232 connector, but they are not the same. This mouse is considerably more valuable if it includes the card it connects to. But it is possible to wire up an adapter so one of these mice can use the much more commonly available 9-pin DIN connector. I’m only aware of Microsoft using this 9-pin connector, but I could be mistaken.

Bus mice were convenient before PCs commonly had two RS-232 ports, but became less common as the 1980s wore on.

Apple ADB

Although Apple ADB is not PC mouse connector type, its Mini DIN-4 connector looks similar enough to other mini DIN connectors that it can be confused for them. So it is worth mentioning.

The easiest way to differentiate ADB from PS/2 is to look at the location of the peg. The peg is further down on the connector and rotated 90 degrees. It also has fewer pins.

Apple used this mouse connector for about a decade, introducing it with the Macintosh SE and Mac II in 1987 and using it through the beige G3, discontinued in the year 2000. Apple switched to USB with the translucent models. NeXT also used this connector in the early 1990s.

An ADB-type mouse will not work on a PC, and it will not fit a PS/2 or bus mouse connector, even though it looks like it might fit. I can’t just tell you to look for an Apple logo either, because third-party mice with this connector did exist.

Incidentally, this is the same connector commonly used for S-Video. So if the connector looks suspiciously like a video connector to you, you are not imagining things.

Thank you

I hope you found this guide helpful. If you see a misidentified listing on eBay or another online marketplace, feel free to send this link to the seller to help them identify their listing better. Or if you are selling something yourself, I hope this guide helps you better identify what you have. This will lead to listings selling more quickly and being less likely to be bought by someone expecting someone else and coming away disappointed and wanting to return it. That’s better for everyone.