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The IrisVision hardware is nearly identical to the graphics sub-system in the SGI Personal Iris workstation introduced in 1988. The hardware supports a 5th generation geometry processing pipeline, the GE5, an 8 or 24 bit per pixel frame buffer, and a 24-bit per pixel z-buffer for hidden surface removal. The card set implements in hardware, the entire IrisGL graphics Application Programming Interface (API).

Notable differences from the Personal Iris graphics are:

  • Uses 256K VRAM instead of 64K VRAM for reduced size
  • Has a 3 color cursor instead of 1 color for increased visibility
  • Has VGA pass-through capability for PC compatibility
  • The card has a rich set of video and rendering modes consistent with the Personal Iris.

The product came to life originally as an OEM graphics board set based upon the VME bus in the Personal Iris. Later, IBM approached SGI to develop a Micro Channel Architecture (MCA) version of the card for use in their newly introduced RS-6000 Unix workstation. IBM licensed the MCA card design as well as the IrisGL graphics library from SGI. In the process of testing the product, it was discovered that an IBM PS/2 model 70 personal computer running OS/2 could be used to run diagnostics and test programs on the card much easier than using the RS-6000. So a minimal device driver was written for the card and soon IBM was shipping product.

At some point, the light went off in someone's head; "Why don't we sell this board set for use in PCs?". IrisVision was born. Initially, the MCA card was re-designed to offer some features critical for the PC market, including standard 15-pin VGA-style video output and a 15-pin VGA passthrough input connector. The IBM genlock connector was moved to the top of the card, and stereo display signals were also brought out to the VGA passthrough connector. The card occupied 1 32-bit MCA slot and an adjacent 16/32 bit slot. One or two daughter boards provided framebuffer and z-buffer memory.

Work then began on the design of an Industry Standard Architecture (ISA or AT-bus) version of the card. It would occupy 2 16-bit ISA slots and use the identical daughter cards as the MCA (and IBM) versions of the board set.


The IrisGL API is implemented in a C-language library developed with the Metaware High-C 32-bit C compiler and the PharLap 32-bit DOS-Extender. It was designed to run in a full screen DOS environment. At the time, M/S Windows did not offer a 32-bit programming environment, so the PharLap DOS-Extender technology was the most sophisticated solution available. It features full 32-bit virtual addressing (2 GB application space), virtual memory support, and seamless integration of real and protected mode programs. The MetaWare High-C compiler is ANSI compatible and is just the ticket for compiling Unix source code to run under DOS-Extender on the IrisVision card.

Video Timing[edit]


				----- Video Resolution ---------------
Parameter			High	Stereo	Medium	NTSC	PAL
Pixel Clock (MHz):		107.3	107.3	64.00	12.27	15.00
Horizontal Freq (KHz):		 63.9	 63.9	48.78	15.73	15.63
Frame Rate (Hz):		 60.0	120.0	60.00	29.97	25.00
Field Rate (Hz):		 60.0	120.0	60.00	59.94	50.00

	Visible Pixels:		 1280	 1280	 1024	  640	  768
	Line Period (uS):	15.70		20.63	63.56	64.00
	Blanking (uS):		 3.73	 	 4.69	11.00	12.00
	Front Porch (uS):	 0.28	 	 1.10	 1.63	 1.67
	Sync Width (uS):	 1.12		 1.25	 4.89	 4.67
	Back Porch (uS):	 2.34		 2.34	 4.48	 5.67

	Visible Lines:		 1024	  492	768	  480	  576
	Front Porch (mS):	0.047		0.062	0.191	0.160
	Sync Width (mS):	0.047		0.062	0.191	0.160
	Back Porch (mS):	0.450		0.804	0.890	1.280

Graphics Modes[edit]


Number of color indexes in ColorIndex mode
Number of bits per component (R:G:B) in RGBmode (intensities = 2^bits)

		----------------------------	----------------------------
MODE		SingleBuffer	DoubleBuffer	SingleBuffer	DoubleBuffer

ColorIndex	256		16		4096		4096

- AntiAlias	 16		 1		 256		 256

- DepthCue	 16		 1		 256		 256

RGBmode		3:3:2		n/a		8:8:8		4:4:4
(TrueColor)	(16.7M - dithered)			(16.7M - dithered)

Auxiliary Bitplanes (Colorindex):

Underlay	 4		 4		 16		 16

Overlay		 3		 3		 15		 15

Popup		 3		 3		 15		 15

Cursor		 3		 3		  3		 3

IrisVision History[edit]

  • 1988: Personal Iris workstation introduced by SGI.
  • 1989: OEM MicroChannel version designed and produced for IBM RS-6000 workstations.
  • 1990: Product announced at the California Palace of the Legion of Honor
    • Product introduced at Fall Comdex in Las Vegas.
  • 1991: Shipments begin, version 2.0 software and SDK released.
  • 1992: Product line acquired by Pellucid, Inc. in turn acquired by Media Vision Technology.
    • Who developed a Windows 3.x display driver for the product.
  • 1996: IrisVision web site deployed on server.
  • 2001: IrisVision web site re-deployed on server after the end of reality

See Also[edit]