HARD DRIVE

The Hard Drive is the permanent storage device for your software operating system, application programs, and data.

Some hard drives are faster than others and have a longer life than others. Performance is measured in it's ability to find information on the drive and how fast it can send it to the CPU for processing. The speed at which it find's information is rated in milliseconds (ms) and is called the average access or seek time. This is a function of how fast the hard drive is spinning, and how fast the read/write heads can move. Seek Times of 9ms or less are considered fast and 12ms or more are slow. The speed at which it can transfer data to the CPU depends upon the hard drive controller it is connected to, the CPU, and the operating system. This quantity is measured in digital Bandwidth or in millions of bytes per second (MegaBytes/second=MB/s). A digital Bandwidth of 10MB/s or more is considered fast while 7MB/s or less is slow. Rotation speeds of 7200rpm or more is fast and 5400rpm or less is slow. Some SCSI hard drives are specifically designed for Audio Visual applications.

Integrated Drive Electronics (IDE) is the most common type of hard drive and has adopted as an American National Standards Institute (ANSI) standard in 1990 as the Advanced Technology Attachment (ATA). IDE provided for hard drives up to 528MB in size.

IDE has now evolved into Enhanced IDE (EIDE). EIDE provides for 28bit Logical Block Addressing (LBA) and drives up to 8.4GB, LBA mode is typically set in today's motherboard BIOS. EIDE also introduced connectivity to CD-ROMs through the AT Attachment Packet Interface (ATAPI). EIDE introduced Direct Memory Access (DMA) and was accepted as an ANSI standard in 1994 known as Advanced Technology Attachment-2 (ATA2). Now a days we have 36bit LBA and ATA3 providing for drives in the hundreds of GBs.

EIDE hard drives employ modes known as Programmed Input Output (PIO) and DMA. PIO mode uses the processor to send information from the hard drive to memory. DMA mode sends data directly to memory freeing up the processor. A DMA drive needs a bus mastering controller.

There were PIO modes 0, 1, and 3. These modes provided for 3.3MB/s, 5.2MB/s, 8.3MB/s under ATA. Under ATA, PIO Mode 4 EIDE hard drive provides a theoretical bandwidth of 11.1MB/s and under ATA2 PIO mode 4 provides for 16.6 MB/s.

There were DMA modes 1 and 2. DMA mode 2 provided for a theoretical maximum bandwidth of 16.6MB/s. Ultra DMA, a.k.a DMA/33, drives have a maximum theoretical bandwidth of 33MB/s. DMA/66 drives have a maximum theoretical bandwidth of 66MB/s, DMA100 provides 100MB/s and DMA 133 provides 133MB/s.

Mixing these various standards and sometimes even hard drives from different manufacturers can cause problems and is not recommended. Although these standards are supposed to be backwards compatible, practical experience shows they are not. I had a PIO mode 3 Maxtor Hard Drive that is slave to a PIO mode 4 Maxtor. I also have a PIO mode 3 CD-ROM that is slave to a PIO mode 4 Seagate hard drive. Every once in a while, the PIO mode 3 Maxtor got "lost" and I would have to use a rescue disk to restore the WIN95 FAT. Not a lot of fun, in fact, the data on this drive was corrupted twice. It is interesting to note that particular hard drive worked fine by itself.

Today's standard is SATA or Serial ATA that can provide 150MB/s of throughput. And SATA 2.0 is just around the corner and promises much higher bandwidth. The main advantage of SATA is smaller cables. This is important as it helps with air flow inside of the case.

The Small Computer System Interface (SCSI) standard allows for both hard drives and other devices like CDROMs and scanners. This standard has continued to evolve from SCSI 1 to SCSI 2 to SCSI 2 WIDE, and to SCSI 3 and even SCSI 3 WIDE, ultra SCSI, ultra2 SCSI, and 160M. SCSI allows up to seven devices and ultra SCSI allows up to 15 devices. Each device has to be assigned a different ID using jumpers. The cable has to be terminated at each end. So remember to set the terminator resistors on the SCSI controller and the last device in the SCSI chain. The SCSI "chain" is the controller, cable, and all devices sequentially connected to the cable. The cable can only be so long. SCSI performance continues to evolve with IDE, one will get a leg up on the other and vice versa. I have had SCSI and have really enjoyed it, they seem to move continuous blocks of data faster than the corresponding IDE and you can get some very large hard drives with small access times. SCSI is, however, more expensive, both adapters and hard drives.

IDE drives were typically smaller than SCSI hard drives. However, this continues to change as both IDE and SCSI evolve.

The larger hard drives have larger block sizes. A block is the smallest segment of data that can be used on a hard drive. If the block size is 64,000 bytes or 64KiloBytes (KB) a small 1KB text file will be written to that block leaving 63KB in that block unused, only one file per block is allowed. Likewise, a 65KB file will take two 64KB blocks leaving 63KB unused in the second block. As the hard drives get larger, the block sizes seem to get larger which translates into more wasted space. That is why multiple smaller hard drives could be the preferred method depending on your situation. However, operating systems like WIN95 and associated applications really like to put everything on the C: drive, so the drives can't be too small. And, IDE only allows 2 devices per controller and there are usually only 2 controllers. So if you plan on using more than 4 drive devices including CDs, consider SCSI.

This section covers a typical IDE hard drive installation starting from the hardware first and the software second.

Consult the Installation manual or look on the hard drive case or hard drive label for this information. Possible configurations include Single, Dual Master, Dual Slave, or Cable Select (Single Neutral). IDE can support two devices per cable and one cable per IDE channel (connector on the motherboard or adapter card). It is possible to have up to four IDE channels (for a total of 8 IDE devices). Most motherboards today have two IDE channels built into them, the primary channel and the secondary channel. The drive that you want to be your boot drive, the drive that the computer will search to find the boot information will be assigned the letter C (referred to as C:), must be configured as the master drive on the primary IDE channel (if you have two IDE devices on the primary channel) or as single (the only device on the primary IDE channel). If you are installing two hard drives on any IDE channel, one has to be configured as the master and the other as the slave. If you are installing only one hard drive, it should be configured as Single. The Cable Select setting requires the adapter and the hard drive(s) to all support a special cable, but, I have never used this. Assuming you will not create extended drive partitions (see FDISK below), hard drive letters will be assigned to the hard drives as shown below, so keep this in mind if you want specific hard drives to be certain drive letters:

IDE CHANNEL	HARD DRIVE	LETTER ASSIGNMENT*
Primary	Master	C:
	Slave	D:
Secondary	Master	E:
	Slave	F:
Tertiary	Master	G:
	Slave	H:
Quaternary	Master	I:
	Slave	J:

The Primary and Secondary IDE channels are commonly available on motherboards and IDE controller cards. The Tertiary and Quaternary IDE channels are sometimes available on IDE adapter cards and sound cards with built in IDE controllers. These devices must be built to allow the customer to configure these additional channels to tertiary and quaternary, not all do.

The next step is to mount the hard drive in a drive bay, connect the power cable, and connect the IDE cable. More on this is found in the motherboard section and more will be added here later.

Windows 2000 and XP does a marvelous job with configuring and formatting and installing itself if you boot from a Windows installation CD. Be sure to select the New Technology File system or NTFS. This wasn't true with older versions of Windows software. The following applies to those older versions that have legacy support back to DOS.

There are two approaches that are determined by your system configuration. If you are installing an IDE hard drive into a computer that has a recent BIOS and operating system that supports the size of the hard drive you are installing as well as the mode of operation, you must boot from a floppy disk and FDISK the hard drive first then FORMAT it. If you are installing a hard drive into a system that does not support these things, then you must use the software that came with the hard drive. Some hard drive manufacturers do not include a separate disk for this software but have installed the software on the hard drive, so don't FDISK and FORMAT the installed hard drive until you know that you either have a separate software disk or have created one by following the instruction manual.

Read the motherboard or adapter manual or peruse the BIOS and look for Logical Block Addressing (LBA) support. And if you are using WIN95 or WIN NT, you don't need the hard drive software. However, if your BIOS doesn't support LBA or if your operating system is DOS or WIN3.X, then you will need the software. I have used the hard drive software before upgrading my motherboard and upgrading to WIN95, but I strongly recommend you upgrade both to support the new larger hard drives and don't fool around with the hard drive software, it is inefficient and difficult to remove. IF you have previously installed this software to a hard drive and wish to remove it, FDISK and FORMAT will not get the job done, you have to use the original software and use a special (often not even found in the software help files) command line switch to remove it. Call tech support for the particular hard drive you have. Be aware that all information on the hard drive will be lost if you remove this software so be sure to backup any data files that you do not want to lose.

The Fixed DISK (FDISK) utility is a DOS command line utility found on the startup disk you created when you installed WIN95 (if you didn't do this, do it now by going to control panel, add/remove software, startup disk tab, and create startup disk). So put the WIN95 startup disk in the A: drive and boot from it, this will take you to the DOS command line prompt A:. FDISK allows you to create a primary DOS partition on any drive. It also allows you to create extended DOS partitions. WIN95 supports primary DOS partitions up to 2.1GB in size, win NT supports larger. If you have an older BIOS that does not support LBA or an older operating system, FDISK will allow a maximum partition size of 512MB. If your hard drive is larger than the maximum primary partition size, you can create an extended DOS partition and then assign the partition a logical drive letter. For example, a 3.5GB drive can have a 2.1GB primary partition that will be labeled C: and can have a 1.4GB extended DOS partition that will be assigned D: so the physical hard drive itself can have more than one letter assigned to it. It is important to note that the drive letter actually refers to the partition.

Note: FDISK is kind of tricky to use and it's menu's and use will be added to this section at a latter date.

After the drive has been FDISK'd, now it needs to be formatted. FORMAT is a DOS command line utility found on the WIN95 startup disk. You use it by specifying the drive you want to format like FORMAT C: then press enter. If the hard drive you are formatting is indeed C:, the boot drive, you will want to make it bootable, so use FORMAT C: /S. The /S tells the FORMAT command to transfer the boot system files after format is complete. If you forgot the /S command, use the DOS command line utility SYS and type in SYS C:. SYS will transfer the boot system files to the C: drive after FORMAT is complete.

To continue to install WIN95, you must first install the CD-ROM drivers if you have the CD-ROM version of WIN95. If you are using the WIN95 upgrade CD-ROM, it will try to locate a previous version of WINDOWS. When it can't find it, simply put the first disk of WINDOWS 3.x in the floppy drive and tell WIN95 where to find it.