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 % 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