النظام الرقمي والنظام التناظري

Digital vs Analog Systems

• Digital systems process data in binary form (0s and 1s).
• Analog systems process data continuously, like sound waves.

Memory vs Storage

• Memory (RAM): A temporary workspace used during program execution. Example: RAM.
• Storage: Media used to save data for long-term use. Example: Hard drives.

Primary Storage (ROM)

• Permanent memory containing essential computer instructions.

Secondary Storage (RAM)

• Temporary memory used during data processing.

Secondary Storage (Hard Disk)

• High-capacity, fast storage.
• Performance depends on:
  • Seek Time: Time to position the read/write head.
  • Spindle Speed: Data transfer speed in RPM.
  • Latency: Time for data to reach the head.

Secondary Storage (CD-ROM and DVD)

• CD-ROM: Stores up to 650 MB.
• DVD: Stores up to 17 GB.

Secondary Storage (USB Flash & Memory Cards)

• Portable and fast storage media.

Types of Storage Technologies

• Sequential Storage: Reads and writes data in order.
• Random Access: Direct data access without sequence.
• Magnetic Storage: Uses magnetic disks or tapes.
• Optical Storage: Reads data using laser beams.
• Solid State Storage: Uses non-volatile memory chips.

Machine Cycle

• Time required to execute a single instruction.
• Steps:
  • Fetch instruction.
  • Decode instruction.
  • Execute instruction.
  • Store results.
• Personal computers execute instructions in less than a millionth of a second.

Summary

• Memory is for temporary use during operation.
• Storage preserves data for the long term.
• Various storage technologies balance performance, capacity, and portability to meet diverse needs.