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Sun Microsystems' UltraSPARC T2 microprocessor, is a multithreading, multi-core CPU. It is the planned successor to the UltraSPARC T1. The chip is sometimes referred to by the codename Niagara II. It is expected to be included in new systems from Sun in the second half of 2007.^[1]

Contents 1 New Features [2] 2 Core Pipeline 3 Tape-Out 4 Performance Improvement: T2 vs. T1 5 References 6 See also 7 External link

The T2 is a derivative of the UltraSPARC series of microprocessors. The processor, manufactured in 65 nm, is available with eight CPU cores, and each core is able to handle eight threads concurrently. Thus the processor is capable of processing up to 64 concurrent threads. Other new features include:

• Speed bump for each thread, increased to 1.4 GHz from 1.2 GHz
• one PCI Express port (x8 1.0)
• two 10 Gigabit Ethernet ports with packet classification and filtering
• the L2 cache size increased to 4 MB (8-banks, 16-way associative)
• improved thread scheduling and instruction prefetching to achieve higher single-threaded performance
• two integer ALUs per core instead of one, each one being shared by a group of four threads
• one floating point unit per core, up from just one FPU per CPU
• eight encryption engines (instead of just one in T1)
• four dual-channel FBDIMM memory controllers

There are 8 stages for integer operations, instead of 6 in the T1.

Processor	Stages
T1's pipeline	Fetch		Thread Selection	Decode	Execute	Memory Access		Writeback
T2's pipeline	Fetch	Cache	Thread Selection	Decode	Execute	Memory Access	Bypass	Writeback

On April 12, 2006, Sun announced the tape-out completion of the T2. It also disclosed that under the same power envelope, the T2 will deliver twice the performance of the T1 when running transactional workload.^[1]

• Integer throughput and throughput/watt (>2x improvement)
• Integer single-thread performance (>1.4x improvement)
• Better floating-point throughput (>10x improvement)
• Better floating-point single-thread performance (>5x improvement)

1. ^ ^{a b} Sun Microsystems Completes Design Tape-Out for Next-Generation, Breakthrough UltraSPARC T2 CoolThreads Processor
2. ^ Niagara2: A Highly Threaded Server-on-a-Chip

• Rock processor

• Niagara II: The Hydra Returns
• Niagara 2 technical features summary with all known details as of 10/2006
• An 8-core, 64-thread, 64-bit, power efficient SPARC SoC presentation that was made on Niagara2 at ISSCC 2007