External devices
| Lecture #4: Hardware architecture |
External devices  | External versus internal storage although the line is not always clear, generally RAM is considered internal, since it is volatile |
| Lecture #4: Hardware architecture |
External devices  | External versus internal storage |
| | Examples of external storage devices punch cards, paper tape, (floppy) disks, hard disks, CD-ROMs, DVDs |
| Lecture #4: Hardware architecture |
External devices | | External versus internal storage |
| | Examples of external storage devices |
| | Important characteristics of storage devices • size (e.g., 2Mbyte) and density(e.g., 1MByte per square inch)
• access speed (e.g., 12ms.) and transfer speed (e.g., 2Mb/sec.)
• access type (sequential or random)
• volatility and lifetime (i.e., average time before data loss) |
| Lecture #4: Hardware architecture |
External devices | | External versus internal storage |
| | Examples of external storage devices |
| | Important characteristics of storage devices |
| | A hierarchy of storage media • closer to the CPU: fewer, faster, more expensive
• farther from the CPU: more, slower, cheaper |
| Lecture #4: Hardware architecture |
External devices | | External versus internal storage |
| | Examples of external storage devices |
| | Important characteristics of storage devices |
| | A hierarchy of storage media |
| | Other external devices (also called "peripherals") examples: mouse, keyboard, speakers, headphones, scanners, printers |