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IBM’s OS/2

IBM’s OS/2. by Chris Axford Chris Evans Elizabeth McGinnis Erik Swensson. HISTORY. IBM and Microsoft partner to make DOS replacement 1987 OS/2 version 1.0 1989 OS/2 version 1.2 1994 OS/2 Warp. Hardware Platforms and Devices. Earliest version used Intel’s 80286 and 80386

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IBM’s OS/2

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  1. IBM’s OS/2 by Chris Axford Chris Evans Elizabeth McGinnis Erik Swensson

  2. HISTORY • IBM and Microsoft partner to make DOS replacement • 1987 OS/2 version 1.0 • 1989 OS/2 version 1.2 • 1994 OS/2 Warp

  3. Hardware Platforms and Devices • Earliest version used Intel’s 80286 and 80386 • OS/2 Warp has expanded hardware compatibility • Communication Devices • 2 MB RAM

  4. User Interface • OS/2 version 1.0 used command line interface • OS/2 version 1.1 provided Presentation Manager

  5. Process Control Block • Standard Format • Traditional Aspects • Pointer • Process ID • Process State • List of Open Files • Program Counters and Registers

  6. Multitasking • Multiple threads per process (user and kernel) • Standard information • Thread ID • Stack • Processor registers • Dispatch state • Priority

  7. Process Communication and Synchronization • Shared Memory • Pipes • Queues • Semaphores • System Semaphores • RAM Semaphores

  8. Scheduling • Multilevel Queue Scheduling Algorithm • 4 Priority groups • Time Critical, Server, Regular, Idle • 32 Queues for each group: total • Each Queue uses Round Robin • Priority Boasts Possible

  9. Memory Management • Memory Protection • Virtual Memory and LRU Algorithm • Memory Segment Sharing • Memory Size Changes

  10. FAT File System • Singly-linked cluster implementation of disk blocks • Fixed size root directory • Advantages • Disadvantages Layout of the 32 bytes in a directory entry in a FAT system. Source: http://www.edm2.com/0411/hpfs1.html

  11. HPFS – High Performance File System • Why the need for HPFS? • Balanced Tree Structure to store files • Advantages to FAT • Disadvatages to FAT

  12. In Conclusion…

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