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Palm OS CS 450 Section 3. Jason Kelske Matthew Jennings Stephen Jou Allan Topp Graham Kerster. Palm OS. Most Popular OS for PDA’s Produced by Palm, Handspring, IBM, Sony, Samsung, some cell phones User Interface offers: Ease of Use Convenience

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Palm os cs 450 section 3

Palm OSCS 450 Section 3

Jason Kelske

Matthew Jennings

Stephen Jou

Allan Topp

Graham Kerster

Palm os
Palm OS

  • Most Popular OS for PDA’s

  • Produced by Palm, Handspring, IBM, Sony, Samsung, some cell phones

  • User Interface offers:

    • Ease of Use

    • Convenience

  • Set the building blocks for the next era of mobile computing

Os objectives
OS Objectives

  • Flexibility

    • Backward Compatibility

      • 16 bit

      • 32 bit

    • Platform

  • Ease of Use

    • User Interface

    • I/O

  • Mobility

Power management

Power Management

Portability and Battery life

Small and light weight

Easily accessible

Easy to carry around


Uses minimal charge

Does not require huge batteries

Does not require a lot of batteries


Power management1

Power Management

System Manager

Controls transitions between different power modes

Three Modes

Sleep Mode

Doze Mode

Running Mode

Provides an API for controlling some aspects

Power management2

Power Management

Three Modes

Sleep Mode

Power is off or after a time period with no user inputs

Display and main clock shuts down

Real time clock and interrupt generator continues to run

Wake up upon an I/O interrupt

Minimal battery usage

Doze Mode

LCD remains on

Displays the main clock

Return to running mode upon I/O interrupt

Some battery usage

Power management3

Power Management

Running Mode

CPU runs as long as it takes to process the users input

Max battery usage

Data and file management
Data and File Management

  • No Traditional File System

    • Data Stored in Chunks or Records in a Database

  • Databases

    • Record

    • Resource

Memory management
Memory Management

  • Memory for Palm OS is on a removable card

    • Card contains both ROM and RAM

      • Volatile vs. Non-Volatile

    • Memory is divided up into “Heaps”

Memory management1
Memory Management

Memory Partitioning

(Image from

Memory management2
Memory Management

  • Each heap includes:

  • a header

  • a master pointer table

  • chunks

  • a terminator

(Image from

Memory management3
Memory Management

  • Movable Chunks vs. Fixed Chunks

    • Lock count

    • Position on the Drive

    • Heap Compaction

Process management
Process Management

Single Process, event driven

  • Process must be single threaded

    • Kernel can have multiple threads

  • Process runs until completion

    • Kernel alerts can take control away from the process

  • When completed, OS switches to new process or to basic OS

  • Synchronization and deadlock not an issue among processes

Event manager
Event Manager

  • Translates I/O events from display to meaningful events for applications

    • Event Manager fires events to current application

    • Application runs in Event Loop until stopping event received

    • Application receives event and uses the appropriate handler


  • Palm OS set the trend for most mobile communication

  • 2 out of 3 PDA’s use Palm OS

  • 85% of business’s include Palm OS in their handheld standards list

  • Windows CE

Thank you
Thank You !

Questions, Comments?