Symbian OS 9.0 was used for internal Symbian purposes only. It was de-productised in 2004. 9.0 marked the end of the road for EKA1. 8.1a is the final EKA1 version of Symbian OS.
Symbian OS has generally maintained reasonable binary code compatibility. In theory the OS was BC from ER1-ER5, then from 6.0 to 8.1b. Substantial changes were needed for 9.0, related to tools and security, but this should be a one-off event. The move from requiring ARMv4 to requiring ARMv5 did not break backwards compatibility.
A Symbian developer proclaims that porting from Symbian 8.x to Symbian 9.x is a more daunting process than Symbian says.
EPOC is a family of graphical operating systems developed by Psion for portable devices, primarily PDAs. EPOC came from epoch, the beginning of an era, but was backfitted by the engineers to "Electronic Piece Of Cheese"
We need Active Objects to perform multi-tasking in a single thread. It is also needed when you deal with client-server architecture inside Symbian. RunL() needs to be kept short as it is an non-preemptive multi-tasking process, it would hang the system otherwise.
According to the two phase constructor idiom all initialisation code that might leave , as well as any call to the fuction that might leave are put together into a constructor call ie; ConstructL() known as the two phase constructor. This is used for proper cleanup if any leave occurs.
Multiple Active Objects in 1 thread and No data synchronisation and context switching overheads
To handle the exceptions in symbian we used the cleanup stack mechanism.The Symbian exception mechanism is based on leaving.The most important issue here is the Cleanup Stack.
One advantage of a Symbian device over J2ME and Brew devices is with hardware access. Symbain has the best hardware access to the phone.
Your registration key can only be used on one device at a time. Should you upgrade or change devices, you can enter your registration info when prompted by the device. The key transfer between your old device and your new one will happen automatically.
technical reasons to do with:
► Functionality and platform integration
► Performance, both in terms of speed and memory footprint
The PersonalJava and JavaPhone APIs on Symbian OS provides perhaps the richest Java environment for mobile phones. As an example we might use this capability to create an application for coordinating a meeting: it would use calendar APIs, contacts APIs, and messaging APIs to negotiate a suitable time and venue amongst the delegates.