The motherboard is mounted directly on the base of the chassis. Figure 2-3 points out motherboard features.

Table 2-1 summarizes the motherboard components. most of which are shown in Figure 2-3.

For expandability, the motherboard includes one AGP (Accelerated Graphics Port) Pro bus, five PCI bus slots, and three DIMM sockets that allow memory installation to a maximum of 1 GB, using synchronous DRAM (SDRAM) DIMMs.

For connectivity, the motherboard supports a speaker-out/line-out, and microphone-in port. Other standard connectivity features are two NS16C550 UART serial ports, one enhanced parallel port with Enhanced Parallel Port/Extended Capabilities Port (EPP/ECP) support, a diskette drive interface, and two embedded hard disk interfaces.

Other features include the following:

This section introduces motherboard features, as follows:

Each node in an SGI Graphics Cluster includes SCSI, IDE, and diskette drive interfaces. A drive cage in each node holds three 5.25-inch drive bays, all externally accessible from the front of the node. Figure 2-5 shows drives in a node.

The SCSI controller chipset supports two Ultra 160 SCSI channels (channels A and B); the interface for each of these is a 68-pin connector on the motherboard. Channel A is cabled to the system drive in the existing drive cage; Channel B accommodates additional SCSI drives, such as a DAT tape drive.

An additional drive cage and one or two drives can be added (see “Options” in Chapter 1); these can be ordered from SGI. This guide contains instructions for installing the drive cage and drives, and for replacing drives.

Figure 2-6 shows the ports on the node rear panel.

For pinouts, see Appendix A, “Technical Specifications”. For information on system PCI cards, see “Expansion Slots”.

For use with the audio card ports on the master node of an SGI Graphics Cluster Series 12, SGI supports audio cables no longer than 3 meters. For uses requiring cables longer than 3 m, you can perform an active conversion to AES digital audio, or convert to balanced audio using an unbalanced-to-balanced converter such as Balance Buddy from Rane Corporation or FP-UBC2 from Radio Design Labs.

Each master and channel node includes a commercial graphics card. In the SGI Graphics Cluster Series 12 system, this AGP card works with SGI ImageSync technology. Upgrades for the graphics cards in the systems will be available; check with your SGI service representative

Each node in an SGI Graphics Cluster Series 12 system includes an SGI ImageSync card. The SGI ImageSync card in the master node provides master synchronization signals to the SGI ImageSync card in each node in the SGI Graphics Cluster Series 12 system.

SGI ImageSync daisy-chain cabling is:

See Figure 2-7.