Revision2 Storage
- 1. Revision Session 2
- 2. Storage Devices RAM Temporary storage Stores current program Random access memory Read from or written to Volatile Power off = memory cleared Internal memory
- 3. Storage devices ROM Permanent storage Read Only Memory Contains the information to boot up the computer Not lost when power down Non-volatile Internal memory
- 4. Internal memory Small memory Faster to access
- 5. Backing storage v internal Mass storage (BS) Fast access (int) Cheaper (BS)
- 6. Hard Disc Magnetic disc Several disks on top of each other Sterile Tracks and sectors Massive memory Random access
- 7. Optical Disks Serial Access Read or written to by laser CD-ROM Read only 650Mb Created by laser and read by laser CD/R Read only WORM Laser created and laser read
- 8. continued CD/RW Magnetico-optical Read many write many Created magnetically read optically DVD Digital Versatile Disk 17Gb Use for films Blu-ray 100+Gb Used for HD
- 9. continued Flash memory Non-volatile Memory sticks, pen drives USB Small, stable and robust Transfer data Slower than RAM, faster than Hard Drive Easily lost or broken
- 10. continued Memory cards Flash Use in digital cameras, MP3, mobile phones Magnetic tape Mass storage Cheap Access slow Used in backups Floppy discs or zips 1.4 Mb Slow and unreliable Zip = large floppy, 750Mb
- 11. Backing up data Don’t mix up with backing storage A copy of the data onto a separate device used in case the original gets corrupted Archive The removal of old data from a computer onto another device so that it can be referred to at a later date