Indigo2 and POWER Indigo2 Technical Report

As a full-featured UNIX workstation, Indigo2 offers network file access, virtual memory, multitasking, and all the UNIX standards that technical users demand. As a next-generation workstation, Indigo2 adds features such as DAT-quality audio processing, a modular design allowing an easy upgrade of CPU board, graphics hoard, or memory configuration, and an option for live video I/O that make it ideal for professional multimedia authoring.

Figure 1 illustrates the Indigo2 central unit with an attached monitor, keyboard and three button mouse. The Indigo2 central unit measures 5.0 inches high by 18.5 inches wide by 18.5 inches deep. Its shape and sturdy construction allow it to be placed beneath a 19" monitor or stand upright on its side.

Indigo2 has four expansion slots; all four slots have EISA bus connectors, two of the slots have GIO64 pipelined bus connectors as well. The EISA bus fully conforms to version 3.12 of the EISA standard allowing the use of a large variety of EISA and ISA expansion cards.

1.1 Indigo2 CPUs

The Indigo2 workstation comes in three, easy-to-upgrade CPU module configurations:

• R4600 version, based on the MIPS R4600SC CPU

• R4400SC version, based on the MIPS R4400SC CPU

• the new, more powerful R8000 POWER Indigo2, based on the MIPS R8000 CPU

The MIPS R8000 represents an entirely new generation of MIPS RISC architecture. The MIPS R8000 processor provides peak floating-point performance of 300 MFLOPS - nearly equivalent to a CRAY Y-MP.

Indigo2 system architecture is designed to take full advantage of the these CPUs. The Indigo2 system buses and main memory buses are 64 bits wide to take advantage of the 64-bit wide processor bus of the R4400SC and R8000 CPUs. The 64-bit wide system bus in Indigo2 has a peak transfer rate of 266 MB per second.

1.1.1 R4400SC Key Features

The R4400SC key features include:

• Highly-integrated single chip

• 8-stage superpipelined architecture

• True 64-bit microprocessor with 64-bit integer and floating-point operations, registers, and virtual addresses

• 5-volt or 3.3-volt technology

• On-chip 16 KB instruction cache (I-cache), 16 KB data cache (D-cache), and secondary cache controller with a 128-bit secondary cache interface that can support a secondary cache size of 1 MB

• On-chip Memory Management Unit (MMU) containing a fully associative Translation Lookaside Buffer (TLB) whose entries have a variable page size ranging from 128 KB to 4 MB

• On-chip ANSI/IEEE-754 standard floating-point unit with precise interrupts

• 32 doubleword (64-bit) general-purpose registers and 32 doubleword (64-bit) floating-point registers

• 36-bit physical address that can access up to 64 GB of physical memory

• Full compatibility with earlier 32-bit MIPS microprocessors

  
  

1.1.2 R8000 POWER Indigo2 Key Features

The MIPS R8000 processor is designed to deliver extremely high floating point performance. The R8000 key features include:

• Multi-component chip set consisting of an integer unit (IU), floating-point unit (FPU), tag RAMS, and 2 MB of data streaming cache

• Four-way superscalar architecture, six operations per clock cycle

• True 64-bit microprocessor with 64-bit integer and floating-point operations, registers, and virtual addresses

• 3.3-volt technology

• 16 KB of instruction cache (I-cache) in IU, 16 KB of dual-ported data cache (D-cache) in IU, 1K entries of branch prediction cache

• Memory Management Unit (MMU) in IU contains a 384-entry, dual-ported, three-way set associative Translation Lookaside Buffer (TLB)

• ANSI/IEEE-754 standard floating-point coprocessor with imprecise interrupts

• 32 doubleword (64-bit) general-purpose registers in IU and 32 floating-point registers in FPU

• 128-bit data bus and a separate 40-bit address bus that can access up to 1TB of physical memory

• Upward compatibility with earlier 32-bit and 64-bit MIPS microprocessors

  
  

The R4400 version of the Indigo2 can be configured with XL Graphics, XZ Graphics, or Extreme Graphics. XL Graphics is the Indigo2 entry graphics subsystem. It makes extensive use of the power of the R4400 CPU by implementing the IRIS Graphics Library application programming interface as a set of highly efficient software algorithms.

The R8000 version of the Indigo2 can be configured with either XZ or Extreme Graphics.

XZ Graphics provides four Geometry Engine processors, a raster engine, high resolution full 24-bit color, and a built-in 24-bit Z-buffer. Extreme Graphics provides eight geometry engine processors, two raster engines, high resolution 24-bit color, and a 24-bit Z-buffer. Extreme Graphics is the most powerful graphics hardware currently offered by Silicon Graphics for a desktop workstation.

To accelerate data transfer between the CPU and the graphics and I/O subsystems, Indigo2 workstations use custom ASICs (Application-Specific Integrated Circuits) designed by Silicon Graphics. These chips manage memory and processor interrupts, handle I/O, control the bus, fill pixels and draw lines, control graphics output, and access color tables, often without CPU intervention. The result is a sustained data-transfer rate of up to 266 MB/second for CPU-to-RAM transfers.

To help speed the transfer of large blocks of data such as frames of bitmapped images used in animation, Indigo2 workstations include a custom chip that supports Virtual DMA (Direct Memory Access). The chip knows the exact physical memory address of each page of virtual memory. A user can request DMA access to a data block using virtual memory addresses, the DMA engine provides direct access to the physical memory where the data is stored, even if the bloc is stored in discontinuous memory. Virtual DMA reduces interrupts and CPU overhead, and runs at maximum speed no matter how busy the operating system is.

Indigo2 supports Fast SCSI-2 for maximum data transfer speed to SCSI devices via a SCSI-2 bus. The SCSI-2 bus operates at up to 10 MB per second on both SCSI-2 channels simultaneously. This bus can support internal hard drives of over one gigabyte of formatted capacity.

Indigo2 workstations provides sound accompaniment to their graphics images with an audio system that supports 24-bit digital stereo and 16-bit analog stereo sounds. It includes line-level and mic-level analog inputs, line-level analog outputs and, for working directly with digital audio, a stereo serial digital input/output jack.

Because many users want to mix incoming video with graphics and to record their work on videotape, Indigo2 graphics boards include a bus to accept an add-on Silicon Graphics video board that handles composite or SVideo signals in NTSC or PAL formats.

1.4.1 Galileo Video

Galileo Video is a video option from Silicon Graphics that transforms an Indigo2 into a professional grade video production console. Some of the many features of Galileo Video include:

• NTSC and PAL standards
• professional quality Y/R-Y/B-Y and RGB formats
• industrial quality S-video and composite formats
• real-time and frame-by-frame video output and video-in-a-window display
• capture of video clips and frames to RAM or disk
• real-time video capture with the Cosmo Compression option
• Genlock to video input or external blackburst
• output of video sync
• SMPTE Vertical Interval Time Code support
• 8-bit per component 4:2:2 YUV color space with no conversions

Real-time processing is designed into the Galileo Video architecture. The alpha blending and key generator features enable on-line editing of many fundamental video effects:

• overlays
• dissolves
• fades
• wipes
• chroma keying
• luma keying