Hack 11 Step Away from the Legacy Device

As the Borg proclaim in many Star Trek episodes, "Resistance is futile. You will be assimilated." So will you find emphasis on moving PC I/O capabilities and devices as far away as possible from legacy technology. ISA technology is bigger, bulkier, and fraught with more configuration complexities and conflicts than the vendors and their support people ever imagined, and it's been more than a bit frustrating for millions of PC users as well. The best way to avoid the rest of this chapter and a lot of frustration and to gain a lot of performance and reliability is to disconnect, remove, disable, and replace all of your legacy devices with PCI, PCI-X, AGP, USB, or IEEE-1394 products.

With systems that provide enough 8- or 16-bit ISA slots (typically the black-colored edge connectors on your system board) to allow you to fill the system up with a lot of ISA devices, it is not unusual to run out of IRQs (Interrupt Request lines), limited resources that the CPU uses to address devices. Over the past few years the number of ISA slots on any given system board has decreased (often to zero) while the number of PCI slots (typically white edge connectors) has increased, and even the number of PCI slots is decreasing as more common functions (network, video, sound) have been built onto the system board. PCI devices do not have the same problems with IRQs that ISA cards have: PCI devices can share IRQs, and modern motherboards can assign IRQs dynamically (with ISA, you usually have to set a jumper on the card).

Finding any new 8- or 16-bit ISA I/O device to expand your system for more external peripherals at a computer store may be next to impossible, and you may be challenged to find documentation on how to configure any of the older boards you come across. Vendors have switched to PCI, and most peripherals have moved from using serial or parallel I/O to USB or IEEE-1394, which are beginning to make the PCI bus for external devices obsolete as well.

Expanding the I/O capabilities of a laptop computer almost certainly forces you into using products based on PC Card (formerly known as PCMCIA), or external USB or IEEE-1394 devices. Many newer laptop computers lack serial or parallel ports, forcing you to purchase USB-to-serial or USB-to-parallel adapters in order to use your older peripherals or connect to the console or terminal ports on routers, switches, and other devices.

Eventually new PCs will lack serial and parallel ports, and PCI slots will be replaced with PCI X and AGP. Many systems are being shipped without diskette drives, preferring rewritable CD-ROM and DVD drives. Even the old style 40-pin IDE drives and IDE interface is giving way to serial ATA interfaces. All this to reduce system complexity, size, cabling mazes, power requirements, cooling requirements, and hardware support burdens. Save yourself a few headaches and gain the advantages of performance and reliability with new PCI- or USB-based hardware.