Neon-komputadór

SCSI and IDE Interface

This topic is relevant to CD Drives, Hard Disk Drives, Motherboards and Input/Output devices. So rather than have the information scattered across the four descriptions, it seems sensible to put it all here in one package. IDE (Integrated Drive Electronics) is the most common means of installing a hard disk drive to a computer, where the interface electronics or controller is built into the drive itself. Contemporary IDE is used not just for hard disk drives, but also for CD drives, DVD drives and high capacity tape drives.

The IDE interface is more officially known as the ATA (AT Attachment) and is an ANSI standard. The name evolves from the fact that it could plug into a 16bit IBM AT bus - long redundant of course. The standard attachment is a 40-pin connector to an ISA bus. ATAPI (AT Attachment Packet Interface) is an IDE standard interface for CD Drives. Usually, a separate IDE connector is required from the one used by the Hard Disk Drive(s), as IDE doesn't handle sharing a single channel of information between different devices that well and often the CD Drive would have to wait for the Hard Disk Drive to complete commands and vice-versa. SCSI does not have this problem.

SCSI (pronounced 'Skuzzy'), although Apple Computers did attempt at one stage to popularize the pronunciation as 'Sexy'), is an acronym for 'Small Computer System Interface'. Since 1986 it has been endorsed by ANSI (American National Standards Institute). A SCSI interface uses a controller card and a 50-pin connector that can connect up to 8 or 16 devices, which avoids the problem of having additional adaptor cards for each new peripheral. Thus, a SCSI card can connect CD Drives, Hard Disk Drives, Tape Drives, Scanners and so forth. Regrettably however, most SCSI host adapters will not include all the features needed to support multiple SCSI devices or bootable hard drives - this is simply due to cost. To put simply, despite its excellent performance, SCSI can be troublesome at times due to the lack of single adapter standard, software interface standard and standard ROM BIOS.

When it comes to CD Drives however, SCSI is pretty much required for writable CD Drive. Writing to a CD usually requires a constant data flow, and IDE simply can't guarantee that. However, for CD ROM Drives, the IDE/APATI interface is undeniably cheaper. Indeed, in comparison to all the other alternatives, IDE has the great advantage of price.