Kernel Expanded version of Kodak’s AMX kernel Features –Uses Preemptive Priority Scheduling –Multithreading –Multitasking

Final Report: Palm OS Thad Cox Gerald Irish Duo Lei Chip Seymour

Typical architecture layers of a PDA

Palm OS Specs CPU speed ranges from 16MHz to 33MHz Random Access Memory (RAM) ranges from 128k to 8MB Dynamic heap ranges from 32K to 256K

Devices Handspring HandEra Sony Palm Inc. Kyocera/QUALCOMM Symbol Technologies

Palm OS Multimedia support for high-resolution 320x320 pixel screens -four times the resolution of most current generation products high-fidelity sound recording and playback

Palm OS Wireless Connectivity support for Bluetooth and b wireless networking standards capable of connecting and communicating with networks and other devices like never before

Palm OS Security & Compatibility 128-bit data encryption based on the RC4 algorithm and Secure Socket Layer (SSL) support for Internet , web browsing, and commercial transactions. backwardly compatible with most existing Palm OS applications

Palm Handheld and Issues concerning Software Applications Screen Size Quick Turnaround expected PC Connectivity Input Method Power Memory Backward Compatibility

Continue… Programming Concepts 1.PilotMain 2.Event Loop 3.Predefined UI and Custom define UI 4.Managers

Memory Broken into three Heaps –Dynamic –Storage –ROM Each heap (except ROM) –Header –Master Pointer Table –Chunks –Terminator

Memory Cont. Dynamic Heap is Palm’s RAM –global variables and data objects, user interface components, buffers, application data, and an application stack –variable size chunks are allocated –two types, movable, and unmovable Movable memory is referenced by ‘handles’ handles reference master pointers which point to the beginning of each memory chunk handles must be locked before memory access a lock counter keeps track of how many locks are on a particular chunk. Chunks can only move when locks = 0

Memory Compaction –compaction is automatically performed whenever there is not enough memory for an allocation the OS does not keep track of when it performed last compaction if after compaction the memory allocation fails again, the system will continue to try which may lead to a system crash

Memory Cont. Storage Heap –where user data and applications reside –data is divided into records in either a resource or record database, logical constructs –multiple databases within memory –records can be accessed by index or searched by one of its attribute fields –each record must be <64K, thus applications should be <64K, however Palm OS supports segmenting

Conclusion Palm’s success comes from its minimalism solutions to design constraints are sometimes suboptimal from a logical standpoint but work well given the application future releases will gain some of the capabilities of desktop machines as PDA hardware advances