palm os christine jones cs 550 section 1 fall 2005
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Palm OS
Christine Jones
CS 550 Section 1
Fall 2005
• About• Success of Palm OS• Handheld Constraints• Power• Memory Management• Chunks• Palm OS version 3.x• Palm OS 5• Palm OS Garnet• Palm OS Cobalt• Summary
About
• Palm 1000 debuted in 1996
• 70 % of handheld market
• OS– Versions 3.1, 3.2, 3.3 were developed for
specific devices– Beginning with 3.5, OS developed for use with
all Palm devices
Success of Palm OS
• Acknowledged differences between handheld device’s system needs and a desktops
• Simple
• Efficient
• Backwards compatible
Handheld Constraints
• Power
• Memory
• Screen
• Time (Speed/Efficiency)
Power
• Palm OS system is always on
• Three modes– Sleep– Doze– Running
Memory Management
• Chunks
• Dynamic Heap
• Storage Heap
• OS and built in apps stored in ROM
• User’s data and installed apps stored in RAM
Chunks
• Memory is divided into chunks and then allocated
• Have a max size of 64 kB
• Two types:– Handles– Pointers
Palm OS version 3.x
• Total Dynamic Memory Area = 96 kB
• Dynamic heap = 64 kB– System Globals = 2.5 kB– Application Stack = 3 kB– (if applicable) TCP/IP stack = 32 kB– Remaining memory <= 36 kB
Palm OS 5
• PACE
• Backwards compatibility
• Advanced RISC Machine processors
• Emulation Mode
Palm OS Garnet
• Based on Palm OS 5
• PACE environment
• Preemptive multitasking kernel
• User Interface Application Shell (UIAS)
Palm OS Cobalt
• ARM processor and PACE (similar to Garnet and OS 5)
• Difference:– Multithreaded applications
Summary
• Successful because of:– Efficiency– Attention to customer needs– Ability to evolve
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