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Have you seen this marketing summary?

INTRODUCTION

This specification describes the RISC-based, high performance, IRIS 4D/70 workstation integrated and manufactured by Silicon Graphics Inc.

For the purposes of this specification the term "workstation" is defined as comprising any and all integrated and configured devices that form a user operable system environment.

REFERENCE DOCUMENTATION
U.S./Domestic Standards

UL-478 - Standard for Safety-EDP Units and Systems
FCC - Regulatory Docket #20780, Part 15, Subchapter J-Class A
CSA - Standard C22.2, No. 154- Safety of Data Processing Systems
ESDI - Preliminary ANSI Working Document Number X3T9.3/86 Revision 1.0 10/20/86
VMEbus Specification, Revision C.1, dated October 1985

European Standards

IEC - Standard 380 - Safety of Office Machines
VDE - Standard 0806 - Safety of Office Machines
VDE - Standard 0871 - Suppression of REI. (Level A compliance required.)
ZH-1 - Standard 618 - Safety Regulations for Display Work Places in the Office Sector

CONFIGURATION SUMMARY

Base Configuration

12-slot twin tower enclosure with power supply, cabling, I/O panel, status panel, 115 VAC power module and cooling

IP4 PCA with 12.5 MHz RISC CPU and Floating Point Coprocessor, and 8 MB of parity memory

170 MB SCSI or 380 MByte ESDI disk with controller

Ethernet PCA

GF3 PCA with 17 Geometry Engines and 4 Geometry Accelerators (all at 10 MHz)

DE2 PCA with 12 user-accessible bit planes

TB2 PCA with twelve-bit-color pixel mapping resource

19" Color Monitor

101 Key full function keyboard

3-Button serial Mouse

Shipping containers

8.3.4 CROSSBAR Custom Chip

There are five (5) pairs of CROSSBAR and PIXELMAP chips in the Workstation graphics subsystem. The CROSSBAR chip allows the graphics subsystem to switch between 3 color models of pixel value representation on a pixel by pixel basis. A graphic cursor is supported by the CROSSBAR via an on-chip SRAM memory. The memory allows a maximum cursor size of 32x32x3, 32x64x1 or 64x32x1 to be displayed with size and positioning determined by software selectable, on-chip registers. The CROSSBAR also supports a ful-screen crosshair style cursor.

8.3.5 PIXELMAP Custom Chip

The PIXELMAP accomplishes the pixel representation mapping by providing a 64x28 bit auxiliary color look-up table for overlays and underlays with flexible auxiliary color selection logic.

The CROSSBAR and PIXELMAP are loaded from the graphics manager (68020) of the GF3 host interface.

8.4 Twelve-Bit Color Map (TB2)

The TB2 board offers a 12-bit color map scheme. The TB2 has no separate hue and intensity mapping. The TB2 communicates with the DE3 color maps loaded from the GF3. The PMAP outputs on the DE3 are carried to the TB2 via an on-board 200-pin connector.

The TB2 provides for a 12-bit in/24-bit out color resource capable of displaying up to 4096 colors from a palette of 16.7 million in one map mode. The TB2 presents fifteen independent maps each with a maximum of 238 RGB entries in a multi-map mode. One of these 238 entry maps is an identity map, allowing RGB. Another map can be configured to do gamma-corrected RGB.

8.4.2 FDAC

The FDAC comprises three custom high speed 8-bit digital-to-analog converters with video controls and 3:1 multiplexer. The FDAC data
conversion dates are capable of maintaining a 123 Mhz video rate required to support the display of 1280 x 1024 bits of information in a 60 Hz non-interlaced manner.
The FDAC output is capable of driving doubly-terminated 75-ohm coaxial cable a distance of 15 feet minimum without external buffering.

8.5 Graphics Options

8.5.1 Z-Buffer (ZB2) Board

The ZB2 provides hardware assistance for hidden surface removal in 3D.
The ZB2 board interfaces to the GF3 and DE3 board via the graphics bus of P2 and P3 connectors.

8.5.2 Genlock (CG2)

The Genlock board option has interfaces to the applications processors, TB2, DE3, and the I/O panel. It gets its power from the system backplane.

When CG2 is installed, workstation internal video/image generation can be synchronized (CG2 supplies master video clock to TB2) with an external video signal via a "remote source in" input connector mounted on the I/O panel of the workstation. The feature will allow for video image blending and overlay of workstation generated images with composite NTSC images from other workstations or video generators such as TV cameras and VCRs.

A second function of the CG2 provides NTSC compatible video output for recording via a VCR or other device. The NTSC output of the CG2 deviates from "broadcast" NTSC.

In general, R, G, and B color triplet information from the workstation display engine (DE) is converted to Y (luminance), R - Y, and B - Y color information and then modulated on a 3.58 Mhz color subcarrier to produce NTSC (RS-170A) color video output.

The NTSC produced by the CG2 differs from broadcast NTSC in two ways; 1) color reference angles are R-Y and B-Y instead of I and Q; and 2) spectral (color range) information.

The CG2 combines R-Y and B-Y components and then bandwidth limits the sum to 0.3 Mhz in order to minimize the delay circuitry (Y component only) required to meet broadcast spec's; i.e. bandwidth limit I to 1.3 Mhz, Q to 0.3 Mhz, delay Y and Q to maintain their relation to I, and then add them together. This means that there will be 1.0 Mhz less spectral color information in the CG2 video than that of true NTSC video.

True broadcast NTSC video may be achieved through the use of an external NTSC encoder in conjunction with the CG2 board option. (No external Genlock (clock generator) device is required since the function is contained on the CG2 board.)

8.6 Ethernet

The Ethernet controller board is standard with the base configuration and conforms to Ethernet 1.0/3.0 (IEEE 802.3).

8.7 Disk Subsystem

The workstation configuration includes one 5 1/4-inch SCSI 170 MByte or ESDI 380 MByte Winchester disk drive. The disk module includes a cooling fan and is designed to allow for simple installation/removal of the disk.

The ESDI disk subsystem includes one Interphase model #V/ESDI-3201 controller in the VME chassis. This controller can support up to two 5 1/4" form factor ESDI disk drives, and 32-bit data transfers and 32-bit addresses on the VME-bus. Additional disk drives require the addition of another ESDI controller.

The Turbo Option processor subsystem also supports an interface to SCSI peripheral devices. An optional 170 MB SCSI Winchester disk drive is available for the system.

8.8 Tape Subsystem

This option includes one 5 1/4" form factor tape drive which supports a 45 or 60 MByte cartridge, has a SCSI interface and an attached cooling fan.

8.9 Monitor

The monitor is a 19" diagonal, high resolution, color CRT display. Monitor resolution is 1280 pixels horizontal by 1024 lines vertical. Horizontal scan rate is 64 Khz. Package includes a tilt/swivel mechanism and anti-reflective coated faceplate.

8.10 Keyboard

101 Key Keyboard with 7 LEDs.

8.11 Mouse

The mouse input device has three buttons, and employs optical technology, operating over a 9.00" x 7.75" grid plate with 200 lpi resolution and RS-423 serial communication interface.

Interestingly, it keeps the "Turbo Option" descriptor, even though as far as I'm aware, all 4D/50 and 4D/70 came with the IP4 which has an on-board SCSI channel.
An unusual amount of hardware is simply for colormapping: both the PMAP chips and the TB2 have independent color maps.