STG chip history

Introduction

STMicroelectronics (formerly SGS Thomson Electronics) has a long history of creating components used for displays and rendering graphics, for example in this Graphics Processors Data Book from 1989.

But relatively few components have carried the STG prefix in their part numbers (STGnnnn). The following four parts of this series details those chips with the STG prefix, both those that made it to market and those that didn't.

STG1000 series

The 1000 series is made up of 5 components, however none were recognisably graphics chips and were in fact components that would be used alongside other graphics chips. The 1000 series were all palette DAC's (Digital-to-Analogue Converter) that are designed to convert digital values to analogue for output via the VGA display connector, with reference to a user defined palette for the 8-bit display modes.

STG1700

The STG1700 was a 44-pin Super-VGA compatible true color (24-bit) Palette-DAC with a 16-bit pixel port. It could run at up to 135MHz and had three 8-bit DACs. This allowed the chip 3 modes of operation:

STG1700 Datasheet

STG1702

STG1702 chip
STG1702 chip

The STG1702 was an evolution of the STG1700 with added support for 2 24-bit pixels every 3 clocks, allowing for 16.7M colors at 1024x768 @ 55Hz.

STG1702 Datasheet

STG1703

STG1703 chip
STG1703 chip

A larger 68-pin chip which was essentially an STG1702 with an on-board clock generator.

STG1732X & STG1764X

These are larger 100 and 128-pin chips containing 32-bit and 64-bit pixel ports (respectively) with three 10-bit DAC's and capable of operation up to 170MHz (135Mhz for the STG1732). The chip featured integrated clock synthesizers, hardware cursor and also support for a gameport for connection of gamepads and joysticks, digital and analogue.

The STG1764X would be found alongside the STG2000, in the upper left part of the card in the image below.

STG1732 & STG1734 Datasheet

STG2000 series

STG2000X chip
STG2000X chip
Source: By Trio3D - Own work, CC BY-SA 3.0
Diamond Multimedia Edge 3D 2120 card showing STG2000X and STG1764X chips
Diamond Multimedia Edge 3D 2120 card showing STG2000X and STG1764X chips
Source: Swaaye at the English-language Wikipedia

Specification:

The story of the STG2000X is really the story of the Nvidia NV1 - the first graphics chip designed by the company that would come to dominate the graphics market in later years. But even they had to start somewhere in January 1993, and their first chip design was a highly ambitious but ultimately unsuccessful product. Intended to be more of a multimedia accelerator rather than pure graphics chip, it included audio hardware for 32-channel sound output, and inputs for Sega Saturn controllers alongside a PC joystick connector.

It also differed in its approach to rendering through the use of Quadratic Texture Mapping (QTM), also used in the 3DO and Sega Saturn, where quads are used to render rather than triangles as used in the majority of rendering hardware.

Virtua Fighter Remix wireframe
Virtua Fighter Remix wireframe showing the quad primitives

Nvidia is, and always has been, a fabless company meaning that it has no facilities to manufacture its own chips. In 1994 capacity at such fabricators was at a premium, however Nvidia was able to find a manufacturer with spare capacity and entered into its first strategic partnership with SGS-Thomson in June of 1994. Releasing its NV1 into the marketplace on the 22nd May 1995.

As part of the agreement, Nvidia would market the NV1 with faster VRAM for the high-end PC market, whilst SGS-T would badge the chip as the STG2000X with slower DRAM and market to the high-volume consumer market.

Unfortunately the product was too expensive in a competitive marketplace due to the additional audio and input functionality and did not sell well. Certainly its audio capabilties didn't offer enough over existing sound card setups to warrant replacing them. The use of QTM also made it an outlier technology with developers who were far more comfortable with using traditinal triangle primitives, and thus didn't support it.

However Sega of America did establish an exclusive licensing deal with Nvidia and ported a number of Sega Saturn and arcade titles to the NV1, including:

Battle Arena Toshinden menu showing NV1 detected
Battle Arena Toshinden menu showing NV1 detected

STG2000 Datasheet

STG2000 Rev C Datasheet (April 1996)

STG2000 Datasheet (Sept 1996)

Nvidia NV1 Windows 95 Software Development Kit 1.50

Nvidia NV1 Customer Evaluation Toolkit v1.22

STG3000 series

Following on from the failure of the NV1, and the cancellation of the successor NV2 chip that was developed for the Sega Dreamcast but not selected, Nvidia was in a poor state financially come 1996. They opted to significantly scale back their workforce by roughly 50% and refocused development efforts for the NV3.

This included dropping the audio and joystick interfaces of the NV1 and switching rendering to use triangle primitives due to it being the defacto standard; whilst also supported by the OpenGL and DirectX API's that were becoming increasingly used for hardware accelerated rendering over proprietary libraries such as 3dfx's Glide, PowerVR's SGL, S3's Metal and nVidia's own NVLIB.

STG3000X

STG3000X chip
STG3000X chip
STB Systems RIVA128 card
STB Systems RIVA128 card
ASUS V3000 with the STG3000X/RIVA 128
ASUS V3000 with the STG3000X/RIVA 128

Specification:

The NV3 was announced on the 8th April 1997, and would be released on the 25th August 1997 as the RIVA 128, where RIVA stood for Real-time Interactive Video and Animation, and the 128 referencing the 128-bit graphics engine. The 128-bit bus to the SGRAM memory offered a very significant 1.6Gbps bandwidth at the time.

As with the NV1, the NV3 would continue to be manufactured by SGS-T and another marketing deal was agreed, although this time Nvidia would market to the US market, whilst SGS-T would market it as the STG3000X to the European, Japanese, and Asian-Pacific markets.

In January 1998 the partners would celebrate the shipping of the one millionth RIVA 128 chip. In 1998 alone SGS-T produced over 5 million Riva 128 and 128ZX chips1.

STG3000 Datasheet

STG3005X

STG3005X/RIVA 128ZX chip
STG3005X/RIVA 128ZX chip

Specification:

STG3005X in an unidentified card
STG3005X in an unidentified card

An updated variant of the NV3, the RIVA 128ZX (NV3T) would be released on the 23rd February 1998 and increased memory support from 4MB to 8MB, including the possibility of using cheaper SDRAM over SGRAM. It also increased the RAMDAC from 230MHz to 250MHz allowing it to support higher resolutions and/or refresh rates. Finally the AGP interface was upgraded from 1X to become one of the first AGP 2X supporting chips.

This variant would be marketed by SGS-T as the STG3005X.

In March 1998 Nvidia formed a strategic partnership with Taiwan Semiconductor Manufacturing Company (TSMC), initially as a second production source for the RIVA 128ZX. However TSMC was to become the main fabricator for the NV3's successor, the RIVA TNT (NV4), and that partnership endures to this day.

It is not exactly clear when SGS-T/STM ceased production of the STG300n chips. It was certainly suggested that they were still in production when STM entered into its partnership with VideoLogic (PowerVR) in April 1999, and would continue to be produced as long as there was demand for the popular chip.

The success of the NV3 architecture undoubtedly saved Nvidia and gave it a solid foundation to develop subsequent successful chips, allowing it to establish itself as a leader in computer graphics and ultimately turning it into the giant it is today.

STG3005 Datasheet

Nvidia SDK Beta v0.81 for Riva 128, 128ZX and TNT (1/9/1998)

Targets DirectX 6.0 (with a custom NVidia bump mapping library), OpenGL 1.2, RIVA 128 [NV3], Riva 128 ZX [NV3T] and RIVA TNT [NV4]. Also contains pre-release RIVA TNT drivers - versions 0.30, August 22, 1998, and 0.32, August 29, 1998.

Nvidia SDK Beta v0.83 for Riva 128, 128ZX and TNT (2/10/1998)