ARM Holdings has taken out a licence for the J2ME technology from Sun Microsystems in a move that will see the companies look at adapting Java further for "the segments that ARM serves", according to Reynette Au, ARM's vice-president of corporate marketing.
As part of the deal, ARM has joined the Java Community Process (JCP), the formal method by which Java is developed and ratified. ARM has some Java licences already, but has previously remained outside the JCP.
ARM intends to apply J2ME support to processor cores that have the Jazelle Java accelerator. ARM will have rights to sub-license the software to customers. ARM staff and Rich Green, Sun's general manager for Java, have confirmed plans to optimise the J2ME implementation.
But Zucotto Wireless, a Java processor designer, warns that, if the two companies set up a special relationship outside the JCP, they risk fragmenting the Java standard.
"Any new Java platforms have to go through the JCP. They are not done individually," said a Zucotto spokeswoman.
Pete Magowan, ARM's executive vice-president of sales and marketing, said: "As part of the Java deal we become participants in the Java community process. As with all partners, there will be an interchange [with Sun] of technology vision, but it will also be conducted within the context of the JCP."
Green denies that the deal gives ARM preferential status over other J2ME licensees: "It's not preferential at all. It gives [ARM] full access, the same as other licensees. In the case of ARM, it's a case of emphasising the partners."
Magowan said that the decision to license J2ME was driven by an anticipated rise in telephone handset designs running Java.
Motorola has had access to the Java technology for some time as the result of its co-development of the core KVM virtual machine. Texas Instruments obtained a J2ME licence last autumn.
Magowan denies the wireless business is vital to ARM's future.
"The 926 [which supports Jazelle] is key to upgrading the existing generation of mobile phones based on the ARM7 core," he said.
"We see Java as very significant in the market but, last quarter, 50% of our royalties came from non-handset business and royalties are 25% of the business."
Tuning for Jazelle
ARM Holdings may find that closer contact with the KVM virtual machine within the J2ME environment will lead to possible optimisations for the software that drives its Jazelle accelerator, assuming that it aims to go deeper than a straight J2ME licence.
Until now, the company has mostly concentrated on providing porting kits for OEMs to develop Java implementations. But it may now start sub-licensinga fully certified virtual machine.
A Jazelle-based ARM does not run bytecode instructions in the same way as a conventional processor. Instead, a conventional virtual machine software loop performs basic checks such as array bounds and illegal actions. The ARM then passes valid byte codes to the Jazelle engine for translation into native ARM instructions.
When running Java, a set of registers in the ARM processor holds the virtual machine's stack.
The current version of the Jazelle support code is designed for the Sun JVM.
By Chris Edwards
Peter Clarke is European correspondent for US sister newspaper EETimes.