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Plug - and - Play (PnP) From NP Technology Plug-and-Play, or PnP, is a specification built into newer systems so that you can install devices built for it with minimal hassle. All of the settings, like IRQ's and drivers, are taken care of so that, theoretically, you can have your new hardware working for you in a couple minutes. The Macintosh had PnP before the PC did. It wasn't till 1993 until it began to take part in the PC world. Four companies took part in this promotion: Microsoft promised a new OS that could take advantage of PnP, Intel promised PnP chips, Phoenix promised the BIOS, and Compaq decided to build the computer. It was realized that PnP could be a real money maker. Installation and configuration could be a real breeze. There would be fewer calls to tech support, and hopefully, people would buy more parts because they weren't daunted by the chore of putting it in. In an ideal world, when you plug in a PnP device, Windows 95 will detect the new hardware, adjust the settings, and install the drivers. Many call it "Plug and Pray", though, because it is rather moody, but the technology has improved greatly, and most installations are hassle free. The Requirements Not all systems can handle PnP. You must have a PnP operating system, such as Windows 95/98/me/2000 or xp. Previous versions of Windows can't do it. Your hardware must be rated for PnP. This means that the system bus must be capable of PnP. The PCI bus was designed with this in mind, and most boards have the ISA slots PnP capable as well by linking them to the same circuitry. You need 32-bit drivers for the device...not to worry though...they come with it. Your peripherals must be PnP compliments, meaning they must be able to accept the settings given to it by the OS as well as have the ability to identify itself to the OS when asked. And lastly, your BIOS must be compliant with PnP. All of these are easy to get, except BIOS. If your system does not already have PnP BIOS, you will need to replace your BIOS, or just upgrade to a new motherboard. All newer computers, say 1995 or later, have PnP BIOS in there already. How It Works A PnP system scans the entire system for new hardware every time the system is booted. It also determines what every device needs, and makes sure it gets it. It scans for legacy devices, or non PnP devices. These devices can't change their settings and have fixed requirements, so the system must first find these, then configure the other PnP devices around it. Although Win95/98 can't automatically adjust a legacy's settings, it can often recognize it during install. Win95/98 has many legacy device drivers built into it. Old hardware will work under 95. If it will work under Win3.x, it will work with 95. Let's walk through the boot process of a PnP computer: 1) Create a table of available resources, including IRQ's, DMA's, and I/O addresses, but not including those required by system devices. Problems! Very simply...plug-and-play doesn't always work. Whether you have all PnP hardware or a mixture of PnP and legacy devices, PnP can be rather hit and miss. One common cause for problems is that the system is attempting to assign settings taken by a legacy device to a PnP device. A PnP system has no adjusting abilities when it comes to a legacy. The more legacy devices you have, then, the more problems you will have with PnP. Another reason is due to the broad array of systems out there. Every system is different, with old drivers, old BIOS, off-brand hardware, you name it. There is no way manufacturer's can design hardware for every possibility. Installers of new devices, though, sometimes find themselves fighting the plug-n-play on their system. PnP is reasonably good at handling simple conflicts, but, is not nearly as resourceful as a human being at thinking through things. PnP simply can't sit there and figure out some clever way to get everything to work without conflicting. Moreover, PnP can be very stubborn. Sometimes, it seems the PC is bent on assigning your new modem to COM 4, IRQ 3, which will conflict with the serial port, despite your best efforts to assign it to COM 3, IRQ whatever. For this reason, some feel the need to slam their computer upside the case with a baseball bat! Trust me, it happens. =) The good news is that PnP problems are on the decline as companies iron out problems as they learn. PnP hardware is getting more and more user-friendly. The Wizard Sometimes Windows just won't detect your new hardware when you boot it up. In this case, you just have to tell it to look for it. You do this in Add New Hardware Wizard in the Control Panel of Win95/98. Again, the Wizard can try to do some strange things at times. Such is the nature of PnP. To avoid trouble, use the nifty "Have Disk" button whenever you do have the disk. Sometimes, the wizard can properly do things and install some Win95/98 stock drivers, but the manufacturer drivers are the best. Some Tips In order to avoid trouble, it is best to make sure that all PnP hardware that you buy has a manual override on it, so that it has legacy capability. The best ones have a set of jumpers. The jumpers are factory set to the PnP setting. But, if you move the jumper bridges, you take it out of PnP mode, and it turns into a legacy. Follow the jumper diagram in the manual to adjust settings manually. Sometimes, you can manually install a new device in this way in case PnP just refuses to detect it for you. Also, go into your Device Manager every once in a while and delete old, unused drivers. When you install new hardware and replace old stuff, Win95 has a habit of leaving the old drivers there, and slow the system down. Make sure you don't delete the CD-ROM drivers or mouse drivers. Also, it is best to buy PnP hardware from major manufacturers. Keep the drivers up-to-date.
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