Disk Control Electronics
When selecting a disk controller you need to be aware of the following things:
1. What type of drive interface does it use?
The two most popular types are EIDE and SCSI. 99% of the new mother boards come with
EIDE controller and a multi-I/O built-in. This means that you may not have to worry about
any of the rest of this information, for any reason other than your own knowledge and
reference to the older motherboards and systems.
EIDE is the best value when comparing size to cost but requires special
equipment, the controller, motherboard bios, and drive itself must all be enhanced to
really gain the benefits. Drives range in size from 720 MB to 100+ Gigabytes. There are a
couple things you might want to consider with the hard drive, but that will be covered in
the appropriate section.
SCSI drives tend to be a little more expensive but are available in sizes
ranging from 345 MB up to 9 GB, and disk arrays are available to create a drive of any
capacity you desire. SCSI controllers also support Scanners, CD-ROM drives, and high speed
tape backup devices. SCSI controllers sometimes have a built-in floppy controller but
seldom take care of the I/O ports.
2. Does the controller support floppy drives?
Not all controllers have floppy support built in, this is more common on motherboards
and SCSI controllers.
3. Does the controller have any built in I/O ports?
Most IDE and EIDE controllers have 2 serial and 1 parallel port built into the
controller, where most SCSI controllers do not have any port built in. If your
Mother-Board already has these ports built in you must beware not to set those ports to
the same addresses as the ports on the controller. You should disable one set or the other
- pick the slowest set to disable (if you can).
4. What speed and type of bus does the controller use?
You must be sure that your Mother-Board supports the bus that your controller is
using. (i.e. ISA, VLB, EISA, PCI).
The current "standards" are 64 bit, 66, 100, or 133 MHz PCI, which nearly 90% of the
motherboards today seem to readily integrate these high-end controllers on the
Bottom line, make sure
that what you get will run in Windows 95/98 and NT in 32 bit mode. And
will give you some future upgradability (even if you never intend to use it - it
adds resale value).
5. Does the controller support cache memory? How much?
Cache memory here is completely different that the cache on the mother board, in
the CPU, or on the drives. This type of cache allows the CPU to concentrate on processing programs while the
controller does the actual searching and retrieving of information from the Hard Disk
An "index" of the files and their locations are saved in this "cache
memory" which can greatly speed up the drive access. Your fastest hard drives and
CD-ROM drives have all of this built right in to the drive itself. Only a handful of
controllers of cache on them, and these are generally expensive. The amount of cache
memory used is entirely user dependent, the more the merrier - generally, there
reaches a point where moving to the next level
becomes too expensive compared to the performance increase.
Copyright 1998 T.E. Mercer, all rights reserved. This page was last updated 16 April 2000