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Rehearsals on Operating systems RAM and traditional memory in a computer

Rehearsals on Operating systems RAM and traditional memory in a computer. Source: Partly from Per S. Laursen. Internal memory. What is internal memory anyway? Just some chips that hold a certain amount of data In a modern computers the internal memory typically consist of 2-16 Gigabyte

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Rehearsals on Operating systems RAM and traditional memory in a computer

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  1. Rehearsals on Operating systems RAM and traditional memory in a computer Source: Partly from Per S. Laursen

  2. Internalmemory • What is internal memory anyway? • Just some chips that hold a certain amount of data • In a modern computers the internal memory typically consist of 2-16 Gigabyte • What kind of data is stored? E.g. music on a mp3 file, that the CPU has to compute to turn it into music. EASJ - Partly from Per's slides

  3. Internal vs. external • RAM as a kind of Internal storage has one big advantage: transfer of data between the CPU and RAM is pretty fast (several Gigabytes per. Seconds) • Fast yes, - but compared to what? • But there are some major drawbacks: • RAM is pretty expensive (compared to what?) • When power is turned off, all data disappear from the internal storage • We therefore also need an external storage EASJ - Partly from Per's slides

  4. The externalmemory/storage • Where does the data in the internal memory comes from? The data comes from the external storage • What is the external storage? Overall, the same as the internal storage, ie a passive storage of data, BUT • Is usually much cheaper than RAM • Retains data when power is turned off • Most common form of external storage in a modern PC is a hard drive EASJ - Partly from Per's slides

  5. A hard item… • Moderne harddiske rummer typisk 200-1000 Gigabyte • A hard disk drive includes a number of magnetic plates, where bits are stored, by magnetising a certain region of the plate • Modern hard drives typically houses 300-4000 Gigabyte EASJ - Partly from Per's slides

  6. Harddrive vs. RAM EASJ - Partly from Per's slides

  7. Harddrive vs. RAM • In otherwords: • RAM: • Very fast and stable, but • Veryexpensive, and does not save data without power/electricity. • Harddrive: • Verycheap and has a bigcapacity, and saves data without power/electricity, but • Veryslowly, and is based on technic EASJ - Partly from Per's slides

  8. Hard drive vs Solid State drive • New: SSD (Solid State Drive). • Faster than Hard drive. • But more expensive than Hard drive.

  9. Harddrive vs. SSD EASJ - Partly from Per's slides

  10. Is a computer ”born” with an Operating system (OS)? • BIOS handles very basic actions as a keystroke, and the drawing of letters on the screen • When a computer starts, the BIOS is set to start • The main task of the BIOS is starting the right operating system • BIOS is a chip in your PC EASJ - Partly from Per's slides

  11. Administration of programs • Last time we discussed what it means, when the virtual memory is larger than the RAM. • When we start a program, it will be copied from the external memory/storage to the internal storage(RAM), and set in motion Operating system The internalstorage(RAM) Program Program Program EASJ - Partly from Per's slides

  12. Administration of programs • The operating system must "find room" for the program in the internal storage - what if there is no more space? Internalstorage Program Program Program Program Program Program Program Program Program Program Whatnow? EASJ - Partly from Per's slides

  13. Administration of programs • The operating system can use some of the external storage (hard drive), as an "emergency extension" to the internal storage Internalstorage Additional(temporarily)internalstorage Program Program Program Program Program Program Program Program Program Program EASJ - Partly from Per's slides

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