Alasir Enterprises
Main Page >  Motley >  MicroHouse PC Hardware Library Volume I: Hard Drives  

Previous Table of Contents Next

Chapter 3
Hard Disk Drive Installation

This chapter thoroughly describes hard disk installation. In particular, the chapter examines the configuration, physical installation, and formatting of a hard disk drive. This chapter also covers the basic procedures necessary to install a hard disk drive into a PC system.

Hard Disk Installation Procedures

To install a hard drive in an IBM-compatible system, you must perform several procedures:

  Configure the drive
  Configure the controller or interface
  Physically install the drive
  Configure the system
  Low-level format the drive (not required with IDE and SCSI)
  Partition the drive
  High-level format the drive

Drive configuration was discussed in Chapter 2, "Hard Disk Interfaces". For complete configuration information, consult the section that covers the type of drive that you are installing.

To begin the setup procedure, you need to know several details about the hard disk drive, controller or host adapter, and system ROM BIOS, as well as most of the other devices in the system.

Controller Configuration

All hard disk controllers and SCSI host adapters require one or more of the following system resources:

  ROM addresses
  Interrupt Request Channel (IRQ)
  DMA channel (DRQ)
  I/O port addresses

Not all adapters use every one of these resources, but some will use them all. In most cases, these resources must be configured so that they are unique and cannot be shared among several adapters.

For most systems, you need the documentation for every adapter in the system to ensure that no conflicts exist and to find out how to reconfigure a card to eliminate a conflict. Software included with your system, such as MSD (Microsoft Diagnostics, which comes with Windows 3.x and DOS 6.x) or the Device Manager in Windows 95 and 98, can help when documentation is not available or is limited. Unless your system conforms to the Plug and Play (PnP) specification, software will normally not be able to identify direct conflicts, but if you install one board at a time, they can identify the addresses or resources that a given board is using.

ROM Addresses

Many disk controllers and SCSI host adapters require an on-board BIOS to function. An on-board BIOS can provide many functions, including

  Low-level formatting
  Drive-type (parameter) control
  Adapter configuration
  Support for nonstandard I/O port addresses and interrupts

If the motherboard BIOS supports a hard disk controller, an on-board BIOS is not needed and, in fact, is undesirable because it uses memory in the Upper Memory Area (UMA). Fortunately, the on-board BIOS usually can be disabled if it is not required.

Only controllers that meet certain standards can run off the motherboard BIOS, including ST-506/412 controllers, ESDI controllers, and IDE bus adapters. These standards include the use of I/O port addresses 170-17Fh and interrupt 14. If you are installing a controller that uses other I/O port addresses or interrupt settings (such as when adding a second controller to a system), the motherboard BIOS will not be able to support it, and an on-board BIOS will be required. XT controllers universally need an on-board BIOS because the motherboard BIOS has no hard disk support whatsoever.

SCSI adapters normally do not emulate the WD1003-type disk interface and almost always require an on-board BIOS to provide disk driver functions. This on-board BIOS supports any of the adapter's settings. In most cases, multiple SCSI host adapters can use the BIOS of the first adapter, in which case the BIOSes on all but the first adapter can be disabled.

If an on-board BIOS is required and enabled, it will use specific memory address space in the UMA. The UMA is the top 384KB in the first megabyte of system memory. The UMA is divided into three areas of two 64KB segments each, with the first and last areas being used by the video-adapter circuits and the motherboard BIOS, respectively. Segments C000h and D000h are reserved for use by adapter ROMs such as those found on disk controllers or SCSI host adapters.

You need to ensure that any adapters using space in these segments do not overlap with another adapter that uses this space. No two adapters can share this memory space. Most adapters have jumpers, switches, or even software that can adjust the configuration of the board and change the addresses that are used to prevent conflict.

Interrupt Request Channel (IRQ)

All disk controllers and SCSI host adapters require an interrupt line to gain the system's attention. These devices invoke a hardware interrupt to gain timely access to the system for data transfers and control. The original 8-bit ISA systems have only eight interrupt levels, with interrupts 2 – 7 available to any adapter. AT bus (16-bit ISA), EISA, and MCA systems have 16 interrupt levels, with interrupts 3 – 7, 9 – 12, and 14 and 15 available to any adapter cards. IRQs 10 – 12 and 14 and 15 are 16-bit interrupts available only to 16- or 32-bit adapters.

Tables 3.1 and 3.2 show the normally used and normally available interrupts in ISA, EISA, and MCA systems and in 8-bit ISA systems. The tables list the default use for each interrupt and indicate whether the interrupt is available in a bus slot.

Table 3.1  ISA, EISA, and MCA Default Interrupt Assignments.

IRQ Function Bus Slot

0 System Timer No
1 Keyboard Controller No
2 Second IRQ Controller No
   8 Real-Time Clock No
   9 Network/Available (Redirected IRQ 2) Yes (8-bit)
  10 Available Yes (16-bit)
  11 SCSI/Available Yes (16-bit)
  12 Motherboard Mouse Port Yes (16-bit)
  13 Math Coprocessor No
  14 Hard Disk Controller Yes (16-bit)
  15 Secondary IDE Yes (16-bit)
3 Serial Port 2 (COM2) Yes (8-bit)
4 Serial Port 1 (COM1) Yes (8-bit)
5 Sound/Parallel Port 2 (LPT2) Yes (8-bit)
6 Floppy Disk Controller Yes (8-bit)
7 Parallel Port 1 (LPT1) Yes (8-bit)

Previous Table of Contents Next