• ISA: a.k.a. AT bus. (found in older 486s and lower speed machines)

• MCA: IBM's own, and very proprietary, flavor of bus. (Currently not in wide use). MCA cards are bus-mastering card.

  Bus mastering cards were a somewhat successful attempt at increasing the efficiency of communications between the card's slot on the motherboard and the processor.

  Basically, read bus-mastering as proprietary hardware architecture.

• EISA (Expanded Industry Standard Architecture): High speed interface still popular but usually found only in file servers, especially Novell fileservers, due to a limited selection of cards on the market made for the EISA type motherboard slot.

  EISA cards are also bus-mastering cards. EISA offers 32-bit throughput and auto-reconfiguration.

  Both EISA and VESA incorporate principles of FLEX. FLEX was originally developed by Compaq Computer Corp. in an attempt to increase the efficiency of communications between peripheral components and the processor.

• VESA Local Bus: This short-lived technology was essentially a direct line between peripheral slot on the motherboard and the processor, very similar to Macintosh bus technology.

  Macintosh developed PDS, processor direct slot, and NuBus both of which involve a direct connection between the processor and peripheral slot.

• PCI is currently enjoying wide acceptance as the bus of choice in the PC industry. PCI slots are found in late model 486s and all Pentium systems.

In fact, it was only really in versions 6 and higher of MS DOS that we started to see memory management integrated into a PCs operating system. The NIC needs to communicate to the processor through a piece of memory.

Typical methods of this are:

• Shared memory - uses up memory that could be put to better use and often causes conflict with other hardware trying to talk to the processor.

• Direct Memory Access - a little better than the shared method, but it uses up a DMA channel that other devices might need to talk to the processor.

• Programmed I/O - you might also call this a memory-mapping card - it has its own little piece of memory to add to the computer and gives the best overall performance of the lot.

• Internal:

  By far and large the most common. 8-bit, 16-bit, 32-bit, 64-bit, 10 mbps, 100 mbps, etc… These cards are simply another circuit board that lives in a peripheral slot on a PCs motherboard.

  Peripheral slots may be filled by many items including: modems, video cards, and controller cards.

• External:

  External interface cards were big before PCMCIA slots hit the market. They are about the size of a package of two Swiss Rolls or a PC's mouse.

  External cards are very nice for technicians since you can install them temporarily without opening a computer case. It also saves time diagnosing hardware problems with internal network interface cards.

  If the network connection works with the external card but not the internal card, it really narrows down your search for the problem.

• PCMCIA:

  Personal Computer Modular Component Interface Adapter? Or how about 'People Can't Memorize Computer Industry Acronyms'. Maybe we should all call them credit card adapters since the shape and size are just about the same.

  PCMCIA slots are externally accessible peripheral slots. Available PCMCIA devices include: NICs, modems, controllers, hard drives, security access cards, etc…

  The advantage is that these devices can be added, and removed without opening the computer's case and many times without even shutting it off. However, installing certain PCMCIA cards involve a complex process of driver loading.