The Four Steps Needed to Make a Hard Disk Usable

SUMMARY

To use a hard disk after it has been installed in a computer, the following four requirements must be met:

1. Identify the drive type in the computer's setup program.



2. The drive must be or must have been low-level formatted.



3. Run FDISK or an equivalent utility to define partitions.



4. At the DOS prompt, type format c: /s to write logical formatting to the disk.

MORE INFORMATION

Each of the above steps is outlined below. Do the following:

1. Identify the drive type in the computer's setup program.
   
   XT Computers

   XT computers usually don't require this step of identifying the drive TYPE. It is included by the drive-specific low-level formatting program described in step 2. For XTs that have CMOS, and therefore have a setup program that may expect the drive TYPE definition, the following information in the AT Computers section applies.

   AT Computers

   On AT (286 or higher) computers, the drive TYPE needs to be identified in the computer's setup program. The setup program may be called Setup, Diagnostics, or Diags, depending on the manufacturer. To run the setup program, boot from the setup disk (for example, IBM PS/2 Reference disk, Wyse 386 Setup disk), or if the ROM BIOS has a built-in setup program, consult the computer's manual on how to invoke setup. Upon reboot, many computers prompt you to press a certain key (for example, F1 or DEL) to start the setup program.

   You have to enter the drive TYPE and issue the save command. This causes the setup program to write the drive TYPE (and other) information into the computer's CMOS, which is a battery-backed memory that the computer reads and then compares to what it actually detects in the system each time it is turned on. If there is a discrepancy, an error is issued and you are prompted to run the setup program to update the CMOS information.
   
   The drive TYPE is an arbitrary number assigned by the computer manufacturer (not the drive manufacturer) to identify a drive with a certain number of cylinders, heads, and sectors. For example, an 80 MB Seagate hard drive may be TYPE 42 on a COMPAQ and TYPE 17 on a Wyse computer.
   
   A computer may not have a drive TYPE available to match the characteristics of a particular drive. In this case, a TYPE needs to be selected that has the same number of heads or less. This is also true for the number of cylinders and sectors. The following is an example of a setup menu:

   SELECT AN OPTION
   
   0 - SYSTEM CHECKOUT
   1 - FORMAT DISKETTE
   2 - COPY DISKETTE
   3 - PREPARE SYSTEM F. MOVING(PARK HEADS)
   4 - SETUP
   5 - PREPARE/LOW-LEVEL FORMAT HARD DISK
   6 - END DIAGNOSTICS
   
   SELECT THE ACTION DESIRED
   

   This example is very similar to the IBM AT Diagnostics (setup) program. Other manufacturers' setup menus may look completely different.



2. The drive must be or must have been low-level formatted.
   
   SCSI and IDE drives are usually already low-level formatted at the factory. In this case, you may continue with step 3.
   
   MFM (17 sectors/track), RLL drives (26 sectors/track), and ESDI drives (over 30 sectors/track) usually need to be low-level formatted.
   
   AT Computers

   On AT computers, low-level formatting programs are usually a choice on the setup program's menu, or these formatting programs come with the computer on a separate disk.

   XT Computers

   On XT computers, you usually have to invoke the DOS DEBUG utility to access a hard-drive-specific program on the controller's ROM to low-level format the drive. Information about DEBUG commands is usually provided in the hard-disk-controller-manufacturer's guide.

   To invoke DEBUG, boot from drive A, insert the disk with the file DEBUG.COM, and press the ENTER key after you type the following:

   DEBUG

   A minus sign (-) prompt will appear. Follow the instructions provided by the hard-disk-controller manufacturer on how to invoke the low-level format program.



3. Run FDISK or an equivalent utility to define partitions.
   
   To invoke this program, boot from drive A, insert the disk with the file FDISK.COM, and press the ENTER key after you type the following:

   FDISK

   The DOS FDISK (Fixed DISK) utility allows you to specify partition sizes and to define which partition will be the active (boot) partition. FDISK then writes the partition table into the first sector of track zero of the partitionable disk. This partition table also contains the master boot block. When the machine is turned on, the ROM BIOS will read this master boot block and transfer control to it. The master boot block then finds out which partition is active, reads the boot code from that partition, and then transfers control to that boot code.
   
   Some versions of DOS (for example, Zenith DOS) have different names for this utility, and some third-party utilities replace FDISK (for example, Diskmanager from ONTRACK Systems) and include many more diagnostic and other features.



4. At the DOS prompt, type "format c: /s" (without the quotation marks) to write logical formatting to the disk.
   
   To invoke this program, boot from drive A, insert the disk with the file FORMAT.COM, and press the ENTER key after you type the following:

   FORMAT C: /S

   The formatting process creates a system of tables, directories, and sector numbers that allows DOS to quickly find certain bytes in a vast sea of 20, 40, or 200 megabytes. This system consists of the following:
   
   
   1. The boot record
   
   
   
   2. The file allocation table
   
   
   
   3. The root directory
   
   
   
   4. The data area
   
   
   The "/S" parameter forces FORMAT.COM to transfer the two hidden system files IO.SYS and MSDOS.SYS (for IBM-DOS: IBMBIO.COM and IBMDOS.COM), and the command processor COMMAND.COM from the boot floppy disk to the hard drive. This allows you to boot with the hard drive.

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