All versions prior to Palm OS 5 are based on top of the AMX 68000[12] kernel licensed from KADAK Products Ltd.

While this kernel is technically capable of multitasking, the "terms and conditions of that license specifically state that Palm may not expose the API for creating/manipulating tasks within the OS.

Version 1.0 features the classic PIM applications Address, Date Book, Memo Pad, and To Do List.

User input is generated through the Graffiti handwriting recognition system or optionally through a virtual keyboard.

Palm OS 3.2 adds Web Clipping support, which is an early Palm-specific solution to bring web-content to a small PDA screen.

It also adds major convenience features that simplify operation, like a context-sensitive icon-bar or simpler menu activation.

[19] This version adds a standard interface for external file system access (such as SD cards).

Now, application code and data need to be loaded into the device's RAM, similar to desktop operating system behavior.

Even with the additional overhead of PACE, Palm applications usually run faster on ARM devices than on previous generation hardware.

With a more powerful hardware basis, Palm OS 5 adds substantial enhancements for multimedia capabilities.

High density 320x320 screens are supported together with a full digital sound playback and record API.

Palm OS 5.3 Simplified Chinese Edition released in September 2003, added full Simplified Chinese support,[24] further support for QVGA resolutions, and a standard API for virtual Graffiti called Dynamic Input Area.

[25] Palm OS Garnet (5.4) added updated Bluetooth libraries and support for multiple screen resolutions ranging from 160x160 up to 480x320.

Garnet OS 5.5 dropped the Palm moniker[26] and, as of 2007[update], is the current version developed by ACCESS.

Palm OS Cobalt introduced modern operating system features to an embedded operating system based on a new kernel with multitasking and memory protection, a modern multimedia and graphic framework (derived from Palm's acquired BeOS), new security features, and adjustments of the PIM file formats to better cooperate with Microsoft Outlook.

Palm OS Cobalt 6.1[30] presented standard communication libraries for telecommunication, Wi-Fi, and Bluetooth connectivity.

For several years, PalmSource had been attempting to create a modern successor for Palm OS 5 and have licensees implement it.

Although PalmSource shipped Palm OS Cobalt 6.0 to licensees in January 2004, none adopted it for release devices.

PalmSource announced it was halting all development efforts on any product not directly related to its future Linux based platform.

[35] As of January 2011, the Access Linux Platform had then yet to ship on any devices, however development kits then existed and public demonstrations had been showcased.

There are five slots for phone or e-mail, each of which may be designated Work, Home, Fax, Other, E-mail, Main, Pager or Mobile (the slot designations cannot be changed) The newer Contacts app adds the following features: several addresses, 9 new fields: Website, Birthday, More phone numbers, Instant Messaging with quick connect.

Empty lines are crowded out by actual events, whose start and stop times are shown by default bracketed in the left margin.

The user must sync with a host computer and view the expense data in a worksheet (templates for Microsoft Excel are supplied).

Usually activated by a press of the physical HotSync button on the Palm's cradle (a dock station), this application communicates with various conduits on the desktop PC to install software, backup databases, or merge changes made on the PC or the handheld to both devices.

For example, a time tracking package could provide a conduit to communicate information between Palm OS and Windows executables.

A Backup conduit included with the HotSync software backs up (and restores, if necessary) most of the data on a Palm OS device.

These include the password needed to display hidden records and unlock the device when locked, as well as set up an automatic lockdown time or inactivity threshold.

Some new features have been added, e.g. support for Address categories, Ringtone associations to users, longer memo texts, etc..

The versions 1.0 and 2.0 run on Palm OS 3.1 or higher handhelds, but they needed a proxy server which has been shut down, so they can no longer be used.

Two officially supported compilers exist: a commercial product, CodeWarrior Development Studio for Palm OS, and an open source tool chain called prc-tools, based on an old version of gcc.