
\noindent
{\bf
Silicon Graphics IRIS 4D/70
}

\noindent
{\bf
High Performance Graphics Workstation
}

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\noindent
{\bf Architecture:}
The 4D/70 CPU is based on a RISC architecture MIPS R2000 chip
running at 12.5 MHz.  The CPU has a 64 Kbyte instruction cache, a
32 Kbyte write-through data cache, a write buffer, and a MIPS
R2010 floating-point coprocessor.  Up to 16 Mbytes of memory are
accessed through a high-speed bus. The CPU can optionally have a
floating-point accelerator based on Weitek parts. Communication
with the graphics processors is through a VME bus.

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\noindent
The Graphics Subsystem operates independently from the CPU. It
includes a number of proprietary VLSI processors and resides on
three to five
triple-high by quad-wide VME boards. Conceptually, graphics
processing is performed by three sections of the Graphics
Subsystem: the Geometry Subsystem, the Rendering Subsystem, and
the Display Subsystem.

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\noindent
The Geometry Subsystem, implemented in 2.0 $ \mu $ NMOS VLSI
technology operating at 10 MHz, includes a 16 MHz 68020 Graphics
Manager with 1 Mbyte local memory for the distributed processing
of graphics tasks.  A pipeline of seventeen 10 Mhz Geometry
Engines handles object rotation, translation and scaling,
six-plane clipping, perspective or orthographic viewing, and
scaling to screen coordinates at over 400,000 3D coordinates/sec.
The IRIS 4D/70 renders 60,000 Z-buffered, Gouraud-shaded four-sided
100-pixel
polygons per second.

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\noindent
The Rendering processor generates pixel addresses, and
performs hardware parallel interpolation of color intensities and
depth values.  

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\noindent
The Display Subsystem includes a three-domain
frame buffer with image planes of 1280 x 1024 24-bit pixels, 8-bit
deep window planes, optional depth planes for rapid hidden surface
removal, and proprietary multi-mode graphics processors which can
read the contents of the frame buffer in five parallel streams.

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\noindent
{\bf Configuration:}
The system is housed in twin towers. One contains a 12-slot
card cage for the CPU, the graphics subsystem, and peripheral
controllers; the other houses the power supply and up to four
stacking storage peripheral modules such as 170 Mbyte hard disks
or streamer tape drives.

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\noindent
Power requirement is 1 KW, and the system is air cooled. The
monitor used is a 19" Hitachi 1280 x 1024 monitor running at 60
Hz.  The 19" monitor weighs 84 lb and has dimensions  18.5"h x
20"w x 21.5"d. The dimensions of the 185 lb twin-tower chasses
are 26"h x 24"w x 27"d.

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\noindent
{\bf Software:}
The operating system is an enhanced version of UNIX V.3
incorporating many features of BSD 4.3 and local enhancements to
support real-time graphics.

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\noindent
{\bf Languages:}
Fortran 77 and C optimizing compilers are available.  Tools
include the IRIS Edge, a window-based graphical interface to DBX,
enabling concurrent viewing of source code execution and results.

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\noindent
{\bf Applications:}
The major application areas are MCAE, animation, industrial
design, visual simulation, and various scientific applications such
as molecular modelling and computational fluid dynamics.

\noindent
{\bf Performance:}
Peak rate is 100 Mflops; sustained rate is 40 Mflops.

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\noindent
{\bf Contact:}
\begin{flushleft}
Forest Baskett\\
Silicon Graphics\\
2011 Stierlin Rd.\\
Mountain View, CA 94043\\
415-960-1980\\
\vspace {.1in}
Gareth Jones\\
Windrush Court\\
Blacklands Way\\
Abingdon Business Park\\
Abingdon\\
Oxon OX14 1SY\\
England\\
0235-554444     FAX 0235-554440\\

\end{flushleft}

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