The SB1 (SiByte-1) core is a highperformance implementation of the MIPS64 architecture. It features 32kB instruction cache, 32kB data cache, 2 integer pipelines, 2 load/store pipelines and 2 fp pipelines. An SB1 core can issue upto 4 instructions per cycle.
The SB1 core is beig used in Broadcom's BCM1250 system on a chip. The BCM1125 is similar but only contains a single SB1 core. The BCM1450 core contain four SB1 cores making it the highest performance SOC using the SB1 core.
BCM1250 is a chip that integrates two 64-bit MIPS CPU cores, each scalable to 600 MHz - 1 GHz, a large cache memory, and integrated I/O. The BCM1250 includes an on-chip 512K L2 Cache and a DDR memory controller that supports up to 2 GB of memory. Overall, the processor can support up to 50 Gbps of peak memory bandwidth. Integrated I/O includes three 10/100/1000 Ethernet MACs configurable to two 16-bit or three 8-bit FIFO interfaces, a 32-bit 33/66 MHz PCI bridge, support for HyperTransport, a high-speed I/O bus for chip-to-chip interconnect, two serial interfaces, a generic bus for direct connection to boot flash, PCMCIA support and on-chip debug features. An evaluation board platform, called the BCM91250A, uses of all the interfaces on the BCM1250, and can be used with any ATX 2.0 compliant case and power supply. Off-the-shelf peripherals including PCI graphics adapters, USB keyboards and mice, and ATA hard disks can be added. The board supports VxWorks 5.4, Linux 2.4 running in 32-bit mode with SMP support, and NetBSD 1.5 running in 32-bit mode.