the Altix 330 is not "brick" based, but is instead based on 1U-high compute modules mounted in a rack and connected with NUMAlink. A single system may contain 1 to 16 Itanium 2 processors and 2 to 128 GB of memory. The Altix 1330 is a cluster of Altix 330 systems. The systems are networked with Gigabit Ethernet or 4X InfiniBand. The Altix 350 is a mid-range model that supports up to 32 Itanium 2 processors. Introduced in 2005, it runs Linux, rather than SGI's own Unix variant, IRIX. The Altix 350 is scalable from one to thirty-two 64-bit Intel Itanium processors. It features DDR SDRAM and PCI-X expansion ports, and can support SCSI or SATA internal hard drives. Designed as a rack-mount server, the Altix 350 is 2U, meaning it occupies two slots vertically in a standard server rack. The Altix 1350 is a cluster of Altix 350 systems. , the Altix 350 was superseded by the Altix 450 (based on the Itanium 2) and the Altix XE (based on the Xeon). The Altix 3300 is a mid-range model supporting 4 to 12 processors and 2 to 48 GB of memory. It is packaged in a short (17U) rack. The Altix 3700 is a high-end model supporting 16 to 512 processors and 8 GB to 2 TB of memory. It requires one or multiple tall (39U) rack(s). A variant of the Altix 3000 with graphics capability is known as the Prism. The 3700 is based on the third generation NUMAflex distributed shared memory architecture and it uses the NUMAlink 4 interconnection fabric. The Altix 3000 supports a single system image of 64 processors. If there are more than 64 processors in a system, then the system must be partitioned. The basic building block is called a C-brick, which contains two nodes in a 4U high rackmount unit. Each node contains two Intel Itanium 2 processors that connect to the Super-Bedrock application-specific integrated circuit through a single front-side bus. The Super-Bedrock is a crossbar switch for the processors, the local RAM, the network interface and the I/O interface. The two Super-Bedrock ASICs in each brick are connected internally by a single 6.4 GB/s NUMAlink 4 channel. A processor node also contains 16 DIMM slots that accept standard DDR DIMMs with capacities of 4 to 16 GB. The Altix 3700 Bx2 is a high-end model supporting 16 to 2,048 Itanium 2