1. Hardware

The Octane's system board is designated as IP30, based on SGI's Xtalk architecture. Xtalk does not use a system bus, but a Crossbow application-specific integrated circuit (ASIC), referred to as Xbow, a dynamic crossbar switch that connects the XIO ports to the hub. One of the ports is used for the processor and memory subsystem, one is available for PCI-X expansion, and four are XIO slots (packet-based high-bandwidth bus, somewhat similar to HyperTransport). This makes it very similar to a single node of the Origin 200 system.

The XIO can be bridged to PCI-X, using a chip named BRIDGE. This bridging includes the system board (for the IOC3 multi-I/O chip, two ISP1040B SCSI controllers and RAD1 audio), MENET cards (four IOC3s) and the PCI cage (used for PCI cards in Octane). The Octane uses ARCS boot firmware, like all contemporary SGI computer systems.

1.1. CPUs

Processors for Octane series computers:

The Octane series has single and dual CPU modules. A second CPU cannot be added; the only option is to replace the whole CPU module.

1.2. Memory

The Octane supports 64 MB to 8 GB of system memory, using up to eight proprietary 200-pin DIMMs. There are two system board revisions. The first revision (part number 030-0887-003) supports 2 GB of RAM, while the second (part number 030-1467-001) allows up to 8 GB. The memory subsystem has vast reserves of bandwidth that can be directly served by the Xbow router to any XIO card.

The Octane's memory controller was named HEART. It acts as a bridge between the processor, the memory (SDRAM) and the XIO bus.

1.3. Graphics

Graphics on the Octane are provided by a series of cards: SI, SI+T, SSI, MXI. These are updated XIO versions of Solid Impact (SI), High Impact (SI+T) and Maximum Impact (MXI) from the SGI Indigo2 that were internally designated by SGI as MARDIGRAS. The boards were accelerated and reengineered with faster geometry engine and texture modules to create their new versions: SE, SE+T, SSE, MXE. The SI/SE provides 13.5 MB of framebuffer memory and the SSE and MXE have a 27 MB framebuffer.

The '+T' indicates an additional high speed Rambus RDRAM-based texture board which gives 4 MB of texture memory, which is practically indispensable, though quite expensive and fragile. The SI/SE+T has one texture board while the MXI/MXE has 2 texture boards, however, the 2 boards in the MXI/MXE do not double the available texture memory to the system. It just doubles the texture performance.

Later Octanes and Octane2's support the SGI VPro graphics board series, designated 'ODYSSEY'. The first VPro series cards were the V6 and V8. The main differentiator being that the V6 has 32 MB of RAM (unlike the MARDIGRAS option, framebuffer memory and texture memory come from the same pool) and V8 having 128 MB. Later, the V10 (32 MB) and V12 (128 MB) were introduced. The main difference with the new VPro V10/V12 series is that they had double the geometry performance of the older V6/V8. V6 and V10 can have up to 8 MB RAM allocated to textures (2X more than the textured-enabled MARDIGRAS options), while V8 and V12 can have up to 108 MB RAM used for textures.

The VPro graphics subsystem consists of an SGI proprietary chip set and associated software. The chip set consists of the buzz ASIC, pixel blaster and jammer (PB&J) ASIC, and associated SDRAM.

The buzz ASIC is a single-chip graphics pipeline. It operates at 251 MHz and contains on-chip SRAM. The buzz ASIC has three interfaces:

• Host (16-bit, 400-MHz peer-to-peer XIO link)
• SDRAM (The SDRAM is 32 MB (V6 or V10) or 128 MB (V8 or V12); the memory bus operates at half the speed of the buzz ASIC.)
• PB&J ASIC

As with the MARDIGRAS boards, all VPro boards support the OpenGL (MARDIGRAS is OpenGL 1.1 + SGI Extensions, and VPro upgraded support to OpenGL 1.2) and OpenGL ARB imaging extensions, allowing for hardware acceleration of numerous imaging operations at real-time rates.

1.4. IMPACT Series

1.5. VPro Series

1.6. Audio

Audio hardware is standard; even without extensions they can support low-latency (3 ms input-to-output) audio streams. Alesis ADAT 8-channel, 24-bit optical ports are built-in, along with S/PDIF or AES/EBU optical and coaxial ports.

1.7. Case and Expandability

The Octane cases are large (30x40x35 cm) and heavy (25 kg), yet there are no internal 5.25" drive bays, so external CD-ROM drives must be connected if desired. Extensions include video I/O, audio I/O, networking, real-time video compression boards, and external storage options (through SCSI, Fibre Channel or FireWire). Octanes can use standard PCI cards with the optional PCI cardcage (which provides one half-length and two full-length 5V 64-bit PCI slots), or a PCI to XIO adapter (known as a 'shoehorn' which provides a single 3.3/5V 64-bit PCI slot). Older Octanes can be upgraded with VPro graphics however V10 and V12 graphics board require Xbow revision 1.4 and a Cherokee power supply. VPro V6 and V8 require Xbow revision 1.3 and a Cherokee power supply. There's distinct difference between the Cherokee (747 watt) and older Lucent (623 watt) power supplies. The mounting handle is silver in the Cherokee International manufactured power supplies while the original Lucent manufactured ones have black handles.

Octane skins come in three types. The original Octane has green skins with the original SGI 'cube' logo. The later model Octanes have skins of the same colour as the original, but with Octane2-style lettering and logos. Octane2 systems have blue skins with the modern lowercase letter-only SGI logo.

1.8. I/O Subsystem

Octane series has two SCSI controllers that supports Ultra Wide SCSI devices. Systems can have a maximum of three internal 3.5" SCSI SCA devices, using proprietary mounting sleds that are also compatible with the Origin 2000, Origin 200 and Onyx2. An external Ultra Wide SCSI port is used for connecting external devices.

1.9. Operating systems

The SGI Octane with IMPACT-class graphics was first supported by IRIX version 6.4. VPro-class graphics have been supported since IRIX version 6.5.10 for V6 and V8, with V10 and V12 graphics supported as of 6.5.11 (or 6.5.10 with a special driver patch).

Linux and OpenBSD have had support.

The content is sourced from: https://handwiki.org/wiki/Engineering:SGI_Octane