1 / 15

Palm OS

Palm OS. Frederick Penrose, Kevin Wong, and Hoan Do. Overview. Memory Management File System Demonstration. Memory Management. ROM vs. RAM. ROM nonvolatile memory stores key applications RAM dynamic & storage stand-by mode (power off) no hard drive

nevaeh
Télécharger la présentation

Palm OS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Palm OS Frederick Penrose, Kevin Wong, and Hoan Do

  2. Overview • Memory Management • File System • Demonstration

  3. Memory Management

  4. ROM vs. RAM • ROM • nonvolatile memory • stores key applications • RAM • dynamic & storage • stand-by mode (power off) • no hard drive • What are the advantages of only using RAM?

  5. Dynamic RAM • size - depends on OS version, available RAM, software, stacks, etc. • dynamic heap • temporary storage for application • global variables, font tables, stacks & structures, library data, buffers (pen & key strokes), etc. • no write protection

  6. Storage RAM • stores application data & databases • persistent • contains one or more storage heaps

  7. Heaps • header • heap ID, status flags, heap size • master pointer table • dynamically built with persistent handles • maps location of each chunk

  8. Memory chunks • size: 1byte – ~64KB • movable • referenced by handles • location: beginning of heap • defragmentation • fixed • referenced by pointers • location: end of heap

  9. Heap Structure

  10. File Systems

  11. Original File System • records & memory chunks • database • no hierarchy • simplicity vs. organization • Why did Palm take this approach and what problems could they run into?

  12. Expansion Card • VFS (Virtual File System) • interfaces with other file systems

  13. New File System • NVFS (Non-volatile File System) • Tungsten T5 and Treo 650 • advantages • non-volatile • hierarchal file system • disadvantage • slower • fixed number of bytes

  14. Average File Size

  15. Demonstration

More Related