10/ 26/ 2013 Storage Devices:

Hard Drives are made up of a stack of Disk Platters with read/ write heads on the top & bottom of each platter. The platters are coated with magnetic film that contains the data bits. They should never be exposed to a magnate because that could erase there data. They have covers to protect their data. Unfortunately floppy disks do not.
Hard Drive size is limited to 137 GB. This is not a physical limit, but by the address the system can support. That limit was set by the BIOS, the OS and the controller to communicate. Earlier systems used 28bits to communicate. 28-bit is limited to 268,435,555 addresses or 137
GBs’. You can flash your BIOS to upgrade it to support a larger number of addresses.
Hard Drives can attach to the motherboard using a number of
Interfaces; PATA, SATA, SCSI, USB & FIREWIRE.
The most common is PATA sometimes referred to as IDE or EIDE.
IDE describes standard drive. Not the connector. It refers to hard, CD,
DVD & Tape Drives and is interchangeable with PATA.
Each PATA/ Parallel ATA; IDE cable has two connectors; a Master &
Slave.
The Motherboard supports two cables; a primary & secondary or four devices total; a primary master and a primary slave; a secondary master and a secondary slave. They may be color coded; Blue:
Primary Channel & Black secondary channel. The cables may be colr coded. Blue plugs into the Motherboard. Black plugs into the 1st device & Grey into the 2nd device.
Master & Slave positions are not determined by the position on the cable, but by jumpers on the drive itself. If you check the label on the drive; you have a choice of master, slave or cable select.

The hard drive should be the only device installed on the primary cable. IDE devices such as CD/DVD or a 2nd hard drive should be installed on the secondary cable. This will improve performance.
There are two types of PATA cables; 40 pins & 40 wires or 40 pins &
80 wires. The extra wires are grounds. Both use a 40 pin connector and have a maximum length of 18 inches.
ATA 100= 100 Mbps
ATA 133= 133 Mbps
Serial ATA connectors or SATAs’ are smaller, faster and more expensive than PATA and have only one drive per cable. If the motherboard supports SATA it can have two or more SATA and two
PATA for a total of six devices connected.
Floppy drives have been replaced by flash, CD and/ or DVD drives.
Todays’ floppy drives uses 31/2” that store 1.44 MB of data. Earlier disk were 51/2” but stored less data.
There are two types of Power Supply Connectors. The larger connector; the Molex is used to power Hard, CD & DVD drives. The smaller connector; the Berg is used to power floppy drives and can be connected upside down. The Floppy drive uses a 34 pin cable to connect to the motherboard. They can be distinguished from the IDE cable because of a twist in it. The connector furthest from the twist attaches to the motherboard. The other connectors are for one or more floppy drives. The red stripe on the cable indicates pin 1 and orients cable for correct installation.
A CD uses indented and raised areas known as pits & lands representing bits; 0 &1 and are laid out in a continuous spiral. A laser, referred to as an optical reader is used to read the bits. There are 3 types of CDs’; CD-ROM read only, CD-R Recordable one time and
CD-RW, recordable multiple times.
DVDs’ have shorter wavelengths; the data is more closely spaced allowing for more data per disk. It writes a second layer and on both sides of the disk to increase capacity.
Single sided/ one layer= 4.7 GB Single sided/ two layer= 8.5 GB
Double sided/ one layer= 9.4 GB Double sided/ two layer= 17 GB
HD-DVD= 30 GB