SGI Indy

Indy's motherboard has a socket for the Processor Module (PM). Early Indys use a 100 MHz MIPS R4000PC microprocessor. The Indy, at the bottom of SGI's price list, was then upgraded with the MIPS R4400 and the low-cost, low-power-consumption Quantum Effect Devices (QED) R4600. The R4600 has higher integer performance, but lesser floating-point capability. The R4600 appears outside the Indy line just once, and only briefly, in the SGI Indigo². This series of microprocessor issues, along with the relatively low-powered graphics boards, lower maximum RAM amount, and relative lack of internal expansion ability compared to the SGI Indigo led to the Indy being pejoratively described amongst industry insiders as "An Indigo without the 'go'."

As the R4600 chip itself has no L2 cache controller, an external controller is used to add 512K of L2 cache. R4600s processor modules, both with an L2 cache (SC) and without (PC), have been produced for the Indy. At the same clock rate, the SC version of the processor module is generally 20 to 40 percent faster than the PC version, due to the memory cache.

The Indy is also the first SGI machine to utilize the QED R5000 microprocessor, which offers significant advantages over the R4400 and R4600 it replaced.

Three graphics subsystems have been produced for the Indy: 8-bit XL, 24-bit XL, and 24-bit XZ. Each support a maximum resolution of 1280 × 1024 pixels at a refresh rate of 76 Hz, and have a 13W3 monitor connection. Graphics options are connected to the system using a GIO32bis bus.

Also known as "Newport" graphics and based on the REX3 chipset, these were designed for general 2D X11 applications; no hardware 3D acceleration is included. This is the first accelerator to demonstrate object-based antialiasing and sub-pixel exact Bresenham lines.

Using a circuit board identical to that of the 8-bit XL, the 24-bit XL includes three times as much framebuffer memory to accommodate 24-bit color.

In an Indy with an R5000 CPU, these graphics options are called XGE, because an R5000 CPU can perform 3D geometry calculations faster than the XZ subsystems's four Geometry Engines. As a result, all 3D is done in software. The situation is, however, reversed when the calculations are done for full-screen rendering and involve z-buffer operations (which XL does not possess). XZ graphics are rarely paired with the R5000 for this reason.

These graphics are a port of the Indigo²'s XZ (Elan) graphics into Indy. They offer very good non-textured 3D performance at the time, sacrificing a bit of 2D performance in return. The XZ graphics option has not been popular in Indy models that used the R5000 microprocessor. This is mostly due to the R5000's MIPS IV architecture, which enhanced MIPS' floating-point arithmetic capabilities, allowing coordinate transformations to be performed faster than the XZ graphics board. However, using XZ to perform coordinate transforms does free the CPU to perform other rendering-related calculations. If the application is not transform-limited (i.e. limited by the speed of coordinate transformation), then the XZ option can provide significant rasterization performance advantages over the XL boards. These graphics take the form of two boards, one on top of the other, and block both GIO option slots, making them less favorable since options such as 10/100 Ethernet and JPEG compression boards cannot be installed.

The Indy is the first SGI to have video inputs by default. Each Indy has an amateur quality composite, S-Video, and digital video input built into the motherboard, which collectively are known as "Vino" (video input, no output) video. The digital input is a SGI Digital Video Interface (proprietary D-sub connector) with a rectangular high density array of 60 pins, and is used by the SGI IndyCam. The connector incorporates two digital video ports, but only uses the first one for input on the Indy. The protocol is similar to the CCIR 601 Parallel Video interface.

The maximum supported input resolution is 640×480 (NTSC) or 768×576 (PAL). A fast machine is required to capture at either of these resolutions, though; an Indy with slower R4600PC CPU, for example, may require the input resolution to be reduced before storage or processing. However, the Vino hardware is capable of DMAing video fields directly into the framebuffer with minimal CPU overhead.

None of the Indys support a video output by default; that would require the Indy Video GIO32 card. Additionally, there is an optional module called CosmoCompress, which offers on-the-fly JPEG video compression and decompression and uses up another GIO32 slot.

The Indy has two drive bays for 1-inch tall 3.5" drives. The upper drive bay is externally accessible and may hold a SCSI floptical drive. All external and internal drives share a single Fast SCSI bus (unless a GIO32 SCSI card has been installed).

External CD-ROM drives connect via SCSI connector at the rear side of the box. The typical drive supports boot, OS install, audio. A special ROM is required to boot from for certain device types.[2] A small number of CD-ROM drives have the firmware needed to do audio over SCSI.

All Indys shipped with AUI/10BASE-T Ethernet and ISDN as standard equipment. The Ethernet ports are half-duplex only. The 10BaseT port takes precedence over the AUI port; if the system detects a carrier on both ports, it will use the 10Base-T.

Two different manufacturers produced 100BASE-TX Ethernet cards compatible with the Indy, both of which attached to the system using the GIO32 bus. Set Engineering produced one such fast Ethernet card, based on the Texas Instruments ThunderLAN chipset, under contract with SGI. Phobos also produced models of fast Ethernet cards for the Indy (the G100 and G130).

The ISDN port provided on the Indy has no NT1. An external NT1 is required to use the ISDN port in North America.