24.1 Hardware and Architecture

24.1.1 Objective 1: Configure Fundamental System Hardware

24.1.1.1 PC BIOS

• The BIOS is the PC's firmware.

• The BIOS sets date and time for onboard clock, storage device configuration, and so on via menus.

24.1.1.2 Resource assignments

• Interrupts (IRQs) allow peripherals to interrupt the CPU.

• I/O addresses are locations in the microprocessor's memory map for hardware devices.

• DMA allows certain devices to work directly with memory, freeing the microprocessor (see Table 24-1).

Table 24-1. Some Common Device Settings

Device	I/O Address	IRQ	DMA
ttyS0 (COM1)	3f8	4	NA
ttyS1 (COM2)	2f8	3	NA
ttyS2 (COM3)	3e8	4	NA
ttyS3 (COM4)	2e8	3	NA
lp0 (LPT1)	378-37f	7	NA
lp1 (LPT2)	278-27f	5	NA
fd0, fd1 (floppies 1 and 2)	3f0-3f7	6	2
fd2, fd3 (floppies 3 and 4)	370-377	10	3

24.1.1.3 1024-cylinder limit

• LILO and the kernel image should be kept within the first 1024 cylinders on hard disks.

24.1.2 Objective 2: Set Up SCSI and NIC Devices

24.1.2.1 NICs

• NICs have been configured using hardware jumpers, nonvolatile memory, and automated means.

• The proc filesystem includes information on interrupts, I/O ports, and DMA in /proc/interrupts, /proc/ioports, and /proc/dma.

24.1.2.2 SCSI

• The Small Computer System Interface (SCSI) defines a bus for multiple storage devices.

• SCSI capabilities range from 5 MBps to 80 MBps and higher for the newest types.

• 8-bit SCSI offers up to seven devices plus the controller on a single bus.

• 16-bit SCSI offers up to 15 devices plus the controller on a single bus.

• Each device on the bus has a unique SCSI ID, 0-7 or 0-15. Controllers often default to address 7.

• Linux device files for SCSI disks are typically /dev/sda, /dev/sdb, and so forth.

• Linux device files for SCSI tape drives are typically /dev/st0, /dev/st1, and so on.

• SCSI buses must be terminated on both ends. Many SCSI devices include internal terminators to eliminate the need for external terminators.

• PC SCSI adapters have their own BIOS, where the default boot device, bus speed, and onboard termination settings can be made.

24.1.3 Objective 3: Configure Modems and Sound Cards

24.1.3.1 Modems

• Modems are serial devices. Some are external and are attached to a serial port. Others are installed in a computer and include serial port electronics onboard.

• Some modems are cost-reduced by implementing portions of their functionality in Windows software libraries. These so-called "WinModems" often aren't compatible with Linux without add-on drivers.

24.1.3.2 Sound devices

• Sound is well-supported under Linux.

• pnpdump output is stored for use at boot time by isapnp, which does plug-n-play configuration.