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 An HPFS file entry Length of file File attributes Pointer to HPFS structure Date/ Time stamp Usage count Length of file (up to 254 characters) Pointer to next level in structure Why the need for HPFS? Balanced Tree Structure to store files Advantages to FAT Disadvatages to FAT

12. In Conclusion…