Oracle has changed its unique formula for determining the cost of running its software on new multicore processors.

Oracle is still pricing its products per processor core rather than per socket, as software companies such as Microsoft have done. But now instead of multiplying each processor core by 0.75, then rounding up to the nearest whole number to determine how many licenses are required for a server, different multipliers will be used for different types of chips, the company said in a press release.

Pricing for software run on servers based on Intel or Advanced Micro Devices's (AMD's) chips will be determined by multiplying the number of processor cores in a server by 0.5, Oracle said. Therefore, an Oracle database running on HP's DL585 with four dual-core AMD Opteron processors would require four licenses, or eight total processing cores multiplied by 0.5.

Sun Microsystems's new T1 processor, formerly known as Niagara, was assigned a 0.25 multiplier. Niagara processors have up to eight separate processor cores, with each core capable of processing four threads. New servers with the chip have only one processor, but the eight-core version of the processor will only require two licenses, Oracle said.

All other multicore chips, such as Sun's UltraSparc IV+ or IBM's Power, will keep the 0.75 multiplier first announced by Oracle in July. Single-core processors will be assigned a multiplier of 1.0.

Software companies have rethought their per-processor licensing models this year as multicore processors have become much more common. Customers had been worried their licensing costs would double if software companies charged them per processing core, rather than per socket, to run the same software on new servers with dual-core chips.

But Microsoft and IBM decided earlier this year to treat dual-core x86 processors such as AMD's Opteron or Intel's Xeon as one processor. IBM considers its own dual-core Power processors to be two chips for licensing purposes.

Oracle noted that customers also have the choice of licensing their software by user, employee, or on a yearly basis.