1 Hard Disk القرص الصلب

2 Construction of the Hard Disk

3 Tracks and Sectors

4 The Difference Between Tracks and Cylinders

5 Platter Size A platter from a 5.25" hard disk, with a platter from a 3.5" hard disk placed on top of it for comparison. The quarter is included for scale (and strangely, fits right in the spindle hole for both platters... isn't that a strange coincidence ?

6 Hard Disk Operational Overview

7 ApplicationTypical Form Factor Platter Diameter Oldest PCs, used in servers through the mid-1990s and some retail drives in the mid-to-late 1990s; now obsolete 5.25"5.12 Standard platter size for the most common hard disk drives used in PCs 3.5"3.74 High-end 10,000 RPM drives3.5"3.0 Laptop drives (2.5" form factor); 15,000 RPM drives (3.5" form factor) 2.5", 3.5"2.5 PC Card (PCMCIA) drives for laptopsPC Card (PCMCIA)1.8 Originally used on hand-held PCs (no longer made)PC Card (PCMCIA)1.3 Digital cameras, hand-held PCs and other consumer electronic devices CompactFlash1.0

8 Read/Write Heads A pair of mated head sliders with their platter removed. You can see that the tension of the head arms has caused them to press against each other.

9 Hard Disk Read/Write Head Technologies

10 سطح القرص This illustration gives you some idea of just how small the flying height of a modern hard disk is (and today's hard disks have flying heights significantly lower than 3-7 millionths of an inch!hard disk

11 Hard Disk Head Sliders, Arms and Actuator

12 Hard Disk Connectors and Jumpers Some of the connectors and jumper pins on a 3.5", 36 GB, 10,000 RPM SCSI Cheetah drive.SCSI

13 Connectors Types IDE Connectors SCSI Connectors SATA Connectors

14 IDE Connectors

15 SATA Connectors

16 SCSI Connectors

17 Data Interface Connector A standard hard disk IDE/ATA data interface connector. If you look closely you can see markings for pins #1, #2, #39 and #40. A 50-pin SCSI interface connector looks identical except that it has 25 columns of pins instead of 20 (they look so much alike that getting the two mixed up is common). A 68-pin SCSI interface connector is pictured on the parent page of this pagethe parent page of this page

18 IDE/ATA Configuration Jumpers Jumper block for an IDE hard disk. The jumpers are labeled "MA" (master), "SL" (slave) and "CS" (cable select). Other IDE drives will have slightly different jumper configuration or placement.

19 Jumpers

20 Hard Disk Logic Board

21 Hard Disk Cache and Cache CircuitryDisk Cache

22 Cache Size The cache chip from a Seagate Barracuda hard disk logic board. This chip is the entire cache: it's a 4 Mib chip, which is 512 kiB, the size of the cache on this drive. Some caches use more than one chip, especially the larger ones.

23 Removable Hard Disk Trays