DOS Days

OPTi Inc.

OPTi were a chipset manufacturer for PCs. Founded in 1989, they competed against SiS, ALI (Acer Labs), Intel and UMC for the desktop 386, 486 and Pentium motherboard chipset industry.

They produced chipsets for Dell, Compaq, Digital, Epson, Fujitsu, Gateway 2000, Hewlett-Packard, PC Chips, Octek, and more.

By 1996, OPTi were really struggling against Intel who had gained a large percentage of the chipset market. Red Hill has this to say about OPTi:

"So long as the 486 reigned OPTi was the world number one chipset maker. OPTi 386 products were excellent and their "495" and "895" i486 chipsets were generally regarded as the best ones on the market. As a chipset maker, Intel went from nowhere to world number one in just a couple of years. Before long Intel had more than 50% of the chipset market with the next biggest player having just 14%. Like all the independent chipset makers, OPTi found the going difficult after this. OPTi did not manage to produce a PCI 486 chipset (at least not one that we ever saw). Nor did they transition to the Pentium promptly. So when the long promised OPTi Viper chipset finally arrived, remembering their excellent 386 and 486 chipsets, we expected that it would be a humdinger. (After all, how hard could it be to improve on the unlovely FX and VX chipsets anyway?) We were to be sorely disappointed. It seems that the Viper had only one thing going for it, a low price."     
Red Hill

 

They produced a few graphics card chipsets, though these days they will be remembered more for their audio chipsets - The Audio Group, a division of the OPTi Multimedia Business Unit, designed all of their audio controllers and provided support to the companies that make adapter cards for retail sale (including BOCA Research, Diamond Multimedia, ExpertColor, EliteGroup, miro, Shuttle, and Turtle Beach), or integrate audio functionality into their system designs. This side of the business was sold in 1997 to Creative Labs.

The "OPTi Bus"

Around the time VESA Local Bus was being developed for faster 486 motherboards, many motherboard and chipset manufacturers came up with their own proprietary buses. OPTi's was called OPTi Local Bus and arrived around 1991.

NEC Technologies was one PC manufacturer to adopt this bus for their Image PC series. It combined a VESA Local Bus (VLB) IDE controller with block mode IDE multiple-sector reads and writes, significantly outstripping performance on competing 486DX/33 and 486DX2/66 systems that ran on the traditional ISA bus.

The slots themselves are typically brown and look similar to the old EISA bus slot but are the same length as an ISA 16-bit slot. Unlike VLB, the OPTi bus doesn't have an "ISA" part to the slot. The motherboard did not necessarily have an OPTi chipset to support the OPTi local bus.

Motherboards that used the OPTi Local Bus include:

  • Chaintech 433SCL
  • Leading Edge 486 boards
  • Orchid Superboard series
  • NEC Image 486es systems

 

Motherboard Chipsets

SCNB (Single chip notebook) 82C463 or 82c263

Click here for a brochure from 1992.

82C281

No information on this.

82C283

No information on this.

82C291, 82C206


A 386 and 486 chipset. BIOS can sometimes report this combo as the "OPTi 349 chipset".

Motherboards known to have used this chipset were:

82C295

No information on this.

82C381

This was a 386 chipset consisting of two chips.
Motherboards known to have used this chipset were:

82C391/82C392B

The 82C392B was used on 80286 and 80386SX motherboards. It was part of the OPTi-386WB PC/AT chipset.

Click here for the datasheet for the 82C391WB.

 

82C465MVB

32-bit 486/586 Mobile Chipset with PCMCIA. 

"The OPTi 82C465MVB chipset is a highly integrated device that supports 32-bit 486 and 5 x 86 architectures. It implements ISA-compatible core logic, with power management and CPU thermal management hardware, in a single device. Its feature set provides an array of control and status monitoring options, all accessed through a simple and straightforward interface. All major BIOS vendors provide extensive software "hooks" that allow system designers to integrate their own special features with minimal effort. The 82C465MVB requires very little board space, implemented as a single 208-pin PQFP package. When used with the 82C602A RTC/Buffer companion chip, the chipset provides necessary interfaces with a minimal amount of support logic."
OPTi website, Nov 1996

 

HiB (82C481, 82C482)

The "HiB" chipset was a 486 chipset with write-through cache. Dated around 1994.

82C491, 82C493

A 486 chipset with write-back cache.

This chipset was used on the following motherboards:

82C495SX / SLC / XLC

A 286, 386 and 486 motherboard chipset from mid-to-late 1990.

Released in early 1991, the 82C495SLC came first - it was a 2-chip chipset along with the 82C206Q integrated peripheral controller chip. It was also given the title "Low-Cost Write-Back". It had unbuffered VESA Local Bus.

Next came the 82C495SX was released. This was a 3-chip chipset, now also coupled with the 82C392SX data buffer controller, and also sold as the LCWB (Low-Cost Write-Back) PC/AT chipset. The key difference between the 495SLC and 495SX was the SX variant had a buffered VESA Local Bus for improved compatibility but slower performance.

Finally in 1993, the 82C495XLC chip was released. Like the SLC, this was back to being a 2-chip chipset along with the 82C206Q integrated peripheral controller chip.

CPU support includes:

  • Intel 80286
  • Intel 386DX
  • Intel 486DX or DX2
  • Intel 486SX
  • AMD Am486DX
  • Cyrix Cx486DLC
  • Intel Pentium OverDrive (P24T)

On a 386 motherboard, this also supported the interesting Cyrix Cx486DLC (and TI or IBM branded variants) drop-in 386 upgrade CPU. Here's a brochure for the chipset from 1992.

Given the flexibility in CPUs, mainboards that used this chipset could run their Front Side Bus anywhere from 25 MHz up to 66 MHz. Boards also supported 80387DX, Cyrix Cx487DLC and Cyrix Cx487SLC math coprocessors.

Boards with the 82C495XLC supported either 64 KB, 128 KB or 256 KB of L2 write-back cache, and usually came with 2 or 3 VESA Local Bus slots. The 495 was known to be an excellent and stable performer. The SLC (not sure about SX or XLC) doesn't support more than 128 KB of cache at 2-2-2-2 timings unless you install 15ns or faster SRAM chips.

Some known motherboard BIOS strings that use this chipset are:
40-081L-001343-00101111-080893-OP495XLC-F - Board Image POST Image
40-0100-001123-00101111-060692-OPWBSK-F
40-040A-001107-00101111-111192-OP495SLC-8

This chipset was used on the following motherboards:

  • A-Trend 3/486 (in both SLC and XLC variants)
  • Jetway J-402B (XLC variant only)
  • Data Expert EXP-3406 (both SLC and XLC variants)
  • DataExpert OPTI-495SX-2VL (SX variant only)
  • Biostar PX486P3 (SLC variant only)
  • Auva CAM/33(50)-P8 M458(A)P80 (SX variant only)
  • See-Thru Data Systems STO 98-5VL (SX variant only)
  • J-Mark OPTI-495SX 3/486WB (SX variant only)
  • UNIC2 94V-0 9326 (SX variant only)
  • BEK-3739 (XLC variant only)
  • Edom MA013 Rev. A (XLC variant only)

I wrote a full review of one of my 386/486 hybrid motherboards which makes use of the 495XLC chipset. Click here to read that article.

82C495SLC

Award BIOS Chipset code: 214UE

Click here for the datasheet for the 82C495XLC.

82C496

No information on this.

82C498

No information on this.

82C499

No information on this.

PTM3V / Python (82C546, 82C547)

The "Python" or PTM3V chipset was released in 1994, designed for the first Pentium motherboards. It supported the P54C 3.3V Pentiums but was also able to work with some components that ran on 5V such as main memory and the ISA bus. It supported ISA, VESA Local Bus and PCI.

The chipset consisted of the 82C546 AT Bus controller and 82C547 System controller. They also work alongside the 82C206 Integrated Peripheral Controller (IPC).

It competed directly with VLSI's "SuperCore 590" chipset.

The datasheet can be downloaded here.

Award BIOS Chipset code: 215UM

Viper (82C556, 82C557, 82C558)

The OPTi Viper chipset arrived in 1995, and comprised the following ICs:

82C556: Data Buffer
82C557: System Controller
82C558: Peripheral Controller

The OPTi Viper Desktop Chipset provides optimum performance and flexibility for 586-class desktop systems. Viper supports all compatible 64-bit processors, including Pentium 60/66/75/90/100, AMD K5 and Cyrix M1, at all frequencies - with a single chipset. The "green" three chip set also features an integrated PCI interface, robust power management and integrated support for dual processor configurations.

Viper offers the highest DRAM and cache performance levels, enabling PC manufacturers to meet all 586-class system price/performance points with a single chipset design. Viper supports a wide variety of existing and emerging DRAM/cache technologies, including synchronous and asynchronous cache. A high-performance no-cache solution is also offered, thus laying the foundation for a cost-effective platform without compromising performance.

  • Supports CPU address pipelining
  • Interfaces the Processor to both PCI and VESA local bus operating in synchronous or asynchronous modes
  • Supports four PCI masters, one VESA slave, and six ISA slots
  • Burst mode PCI accesses to local memory support
  • Adaptive write-back, direct-mapped cache with size selections: 64KB, 128KB, 256KB, 1MB and 2MB
  • Support for both synchronous, pipelined burst synchronous, asynchronous SRAMs, and third-party single-chip cache modules
  • Programmable cache write policy:
    • Adaptive write-back
    • Write-back
    • Write-through
  • Built-in TAG auto-invalidation circuitry
  • Fully programmable cache burst read/write cycles
  • Synchronous SRAM: 3-1-1-1 burst read/write cycles; 1-1-1-1 pipelined cycles
  • Asynchronous SRAM: 3-2-2-2 burst read/write cycles; 2-2-2-2 pipelined cycles
  • Support for two programmable non-cacheable memory regions
  • Options for cacheable, write protected, system and video BIOS
  • Supports six banks of 64-bit wide 256KB, 512KB, 1MB, 2MB, 4MB, 8MB or 16MB DRAMs
  • Supports DRAM configurations up to 512MB
  • Support for EDO and fast-page-mode DRAMs with mix/match capability
  • Supports 3-3-3-3 pipeline DRAM burst cycles: page hit burst read 8-3-3-3; burst write 4-3-3-3 cycles at 66MHz
  • 64-bit DRAM post write buffer with sustained burst capability
  • Hidden refresh with CAS-before-RAS refresh supported
  • Self-refresh supported during Suspend Mode
  • Supports for flash ROM
  • Shadow RAM option
  • Gate A20 and fast reset support for 8042 emulation and port 92h

Viper-N

"In October 1994, OPTi released the Viper-N, the leading solution for Pentium processor PCI-based mobile applications. Viper-N features advanced power management capability and flexibility for Pentium processor-based notebooks. The chipset incorporates desktop-like performance features such as L1 and L2 cache support, a full 64-bit DRAM controller and an integrated PCI controller, in an integrated chipset comprised of three chips."
OPTI website, Nov 1996

 

Viper-N+ (82C557M, 82C558E)

The "Viper N+" chipset was designed for notebooks. Released in 1995, it consisted of the 82C557M System controller and 82C558E Peripheral Controller, plus supporting chips. It supports ISA, VLB and PCI buses, and 64-bit CPUs like the Pentium 75/90/100/120 on 66 MHz bus frequency. It also supports the Cyrix 6x86 CPU. A brochure can be found here.

"The Viper-N+, the leading solution for Pentium processor PCI-based mobile applications. Viper-N+ features leading edge power management capability and flexibility for Intel Pentium, and Cyrix 6x86O processor-based notebooks. The chipset incorporates desktop-like performance features such as L1 and L2 cache support, a full 64-bit DRAM controller and an integrated PCI controller, in a highly integrated three chip set."
OPTi website, Nov 1996

 

VIPER NK/N+

A mobile (laptop) motherboard chipset from 1996 that consisted of the following:

82C557M
82C558E

Viper DP

A dual processor chipset from 1994 made up of:

82C556
82C557
82C558

Viper-M / Viper Max (82C566, 82C567, 82C568)

In October 1995, OPTi released the Viper Max, their fifth generation Pentium chipset. The ViperMax provides enhanced CPU/memory performance, increased PCI transfer bandwidth, fully concurrent buses and add-on optional Unified Memory Architecture (UMA), synchronous DRAM and Universal Serial Bus (USB) support are also included.

Its chipset comprised the following ICs:

82C566
82C567
82C568

Viper Max - UMA Pentium Processor Solution: The optional Unified Memory Architecture enables system manufacturers to save one to two megabytes of DRAM per system, thus reducing total system cost. This is accomplished through the UMA approach of sharing main memory DRAM signals between the system memory controller and the graphics controller. This product can also be configured as a non-UMA product and can be scaled to meet various system level design requirements.

Viper-M - Multimedia-Enhanced Core Logic Chipset: The Viper-M, the second generation of the Viper family, is a multimedia-enhanced core logic chipset for Pentium-class PCI desktop systems. Viper-M provides a high performance, flexible, cost effective system level solution in a highly integrated three-chip set. The Viper-M is the leading chipset solution for corporate users as well as the fast growing consumer PC, small office/home office market. Like the Viper-N, the Viper-M chipset provides complete software compatibility for systems based on any Intel Pentium Processor, AMD 5k 86 or Cyrix 6x86.

AwardBIOS CMOS Setup Utility User's Guide for OPTi Viper-M (82C556M, 82C557M, 82C558M) (EliteBIOS v4.51PG) - for BIOS Part #2A5UNxxx.

The Viper-M chipset was used on the following motherboards:

82C571, 82C572

A 486 and Pentium motherboard chipset with support for VESA Local Bus and write-back cache. Click here for a brochure.

Known for its poor performance. Used in Compaq PCs.

Superceded by the "Viper M". It had no level 2 cache onboard but typical motherboards (Compaq included) got a COAST slot so you could install a 256 KB level 2 cache module.

PTMAWB (82C596, 82C597)

A motherboard chipset for the Pentium CPU family.
The 82C596 uses a VLB-to-PCI bridge chip, the 82C822 to implement PCI functionality. Click here for a brochure from 1992.
Motherboards that use this chipset are: TMC PCI54PV

 

Discovery (82C650, 82C651)

The OPTi Discovery chipset provides a highly integrated solution for a fully compatible, high performance PC/AT platform based on the Intel Pentium Pro processor. The features of the chipset can be scaled to address entry level PCs or high-end desktop or workstation based on Intel's Pentium Pro Processor.

82C682

A 386 and 486 motherboard chipset with support for the EISA bus. 486 supports write-back cache.

82C683

A 386 and 486 motherboard chipset with support for the EISA bus. 486 supports write-back cache.

82C691, 82C696

A motherboard chipset with support for the EISA bus.

EISA pentium (82C693, 82C697)

Here's a brochure on the EISA Pentium chipset, dated 1993.

FireStar (82C700)

OPTi's FireStar single chip combines high performance features with space saving design capabilities for mobile applications. This solution is based on the Intel 3.3V Pentium processor, Cyrix 6x86 processor, and AMD K86 processor. The scaleable features of FireStar allow design of a high performance multimedia solution, or, by implementing the UMA features, a highly-integrated low-cost solution.

VENDETTA (82C750)

In June 1996, OPTi announced the Vendetta (82C750) single chip BGA. This product provides an extremely integrated solution for fully compatible, high performance PC/AT platforms. It supports the Intel 3.3V Pentium processor, Cyrix 6x86 processor, and AMD 5k 86 processors. As the latest member of OPTI's Desktop Chipset family, it has been designed to be the highest performance Pentium processor-based chipset on the market.

scwb2 (82C801)

A 486 motherboard chipset with support for VESA Local Bus and write-back cache. Click here for a brochure from 1992.

82C802 / GREEN (82C802G) / 822

Here's a brochure for this 486 chipset, dated 1993. Supports level 1 write-back cache.

Award BIOS Chipset code: 2A4UK (Phoenix Technologies website claims this is 2C4UK).

AwardBIOS CMOS Setup Utility User's Guide for OPTi 802G (EliteBIOS v4.51PG) - for BIOS Part #2C4UKxxx.

Motherboards that use this chipset are:

  • Soyo SY-030E2
  • Octek Hippo DCA2-486VLB

TRUE GREEN (82C895)

OPTi's final 486-generation motherboard chipset. It supports 486SLe, 486SX, 486DX, DX/2, DX/4 CPUs and write-back CPUs like the OverDrive (P24T). Motherboards with this chipset had ISA and VESA Local Bus expansion slots. Here's a brochure from 1994.

Supports level 1 write-back cache.

Some motherboards that use the 82C895 chipset are:-

419R1 Socket 3, Atrend OPTI895 Green, Dataexpert EXP4044VL, Shuttle HOT-419

 

Graphics Card Chipsets

OPTi 92C178 (1998)

"The OPTi 92C178 provides an unmatched price/ performance LCD VGA solution for portable IBM compatible personal computers. The 92C178 offers high performance, full integration, low power consumption, complete panel support, and simultaneous LCD/CRT display as part of a highly integrated graphics subsystem."
OPTi website, 1996

 

High performance is made possible by a built-in fixed function graphics accelerator. The accelerator supports BitBlt, polygon fill, line draw, color expansion, and clipping. Acceleration is supported for pixel depths of 8, 15, 16, and 24 bits/pixel. Hardware cursor support and linear addressing support further enhance performance in GUI environments by removing software cursor overhead and eliminating bank switching.

Features:

  • 100% hardware/BIOS compatible with IBM VGA standard.
  • Integrated true color RAMDAC and clock.
  • Built-in graphics accelerator. Supports BitBlt, polygon fill, line draw, color expansion and clipping.
  • 32-bit direct interface with VESA local bus and PCI bus, and 16-bit direct interface with ISA bus.
  • Flexible DRAM configurations:
    • One/two/four 256Kx16 DRAMs.
    • Four/eight/sixteen 256Kx4 DRAMs.
  • Direct interface to dual scan color/mono STN, single scan color/mono STN, and TFT panels.
  • Supports panel resolutions of 640x480, 800x600 and 1024x768.
  • Supports CRT display resolutions up to 1280x1024-256 colors.
  • Provides simultaneous LCD/CRT display at resolutions up to 1024x768 non-interlaced.
  • Support simultaneous display for dual scan STN panel with one 256Kx16 DRAM.
  • Supports up to 16.8 million colors on both CRT and color LCD displays.
  • Supports up to 256 gray shades for monochrome LCD displays.
  • Hardware cursor (32x32x2 and 64x64x2).
  • Hardware pop-up icon (64x64x2 and 128x128x2).
  • Programmable linear addressing.
  • Supports the following LCD display adjustment features:
    • Text mode contrast enhancement.
    • Reverse video for graphics and text modes.
    • Vertical expansion and auto-centering.
  • Advanced power management to minimize power consumption:
    • Remove backlight power.
    • Hardware/Software activated Standby Mode.
    • Hardware/Software activated Suspend Mode.
    • Deep Sleep Mode.
  • Power sequenced control outputs to regulate the power supplies for panel and backlight.
  • 3.3V/5V mixed voltage operation.
  • Supplied with a fully compatible VGA/VESA BIOS, drivers for operating systems, such as Windows, OS/2, and UNIX, and OEM and end-user level utility software.
  • Low-power, high-speed CMOS technology.
  • 208 pin QFP package.

Architecture:

The OPTi 92C178 contains the following major functional modules:
  • Bus Interface Unit
  • Write Buffer Control Unit
  • Graphic Controller
  • Memory Sequencer
  • Video FIFO
  • CRT Controller
  • Attribute Controller
  • GUI Engine
  • Hardware Cursor
  • Pop-up Icon
  • Frame Buffer Controller
  • RAMDAC
  • Dithering Engine
  • Flat Panel Interface Controller
  • Power Management Unit
  • Power Distribution Module
  • Clock Synthesizer
  • Multi-media Module

Drivers: Windows 95, NT 4.0

OPTi 82C264 (1998)

"OPTi's 82C264 True-Color GUI Accelerator is a one-chip solution which provides an unmatched price/performance VGA solution for personal computers. The 82C264 offers high performance and full integration as part of a PCI graphics system. Its high performance is made possible by a built-in fixed function graphics accelerator. The accelerator supports BitBlt, polygon fill, line draw, color expansion, and clipping. Acceleration is supported for pixel depths of 8, 15, 16, and 24 bits per pixel. Hardware cursor support further enhances performance in GUI environments by removing software cursor overhead. The 82C264 is 100% register level compatible withthe IBM VGA standard."
OPTi website, 1996

 

The OPTi 82C264 True-Color GUI Accelerator provides an unmatched price/performance VGA solution for personal computers. The 82C264 offers high performance and full integration as part of a PCI graphics subsystem.

High performance is made possible by a built-in fixed function graphics accelerator. The accelerator supports BitBlt, polygon fill, line draw, color expansion, and clipping. Acceleration is supported for pixel depths of 8, 15, 16, and 24 bits per pixel. Hardware cursor support further enhances performance in GUI environments by removing software cursor overhead.

The RAMDAC and clock synthesizer are built into the 82C264. No external logic is required to connect to the PCI bus. A complete VGA video subsystem can be implemented with two 256Kx16 DRAM chips. CRT display resolutions up to 1280x1024 with 256 colors are supported.

The OPTi 82C264 is 100% register level compatible with the IBM VGA standard. OPTi supplies a fully compatible VGA/VESA BIOS, drivers for common applications and operating systems, such as Windows, Windows 95 and OS/2, as well as OEM and end-user level utility software.

Features and Benefits:

Features Benefits
Integrated true color RAMDAC and clock. Full integration. One chip solution.
Built-in graphics accelerator. Supports:
  • BitBlt
  • Polygon fill
  • Line draw
  • Color expansion
  • Clipping
  • 24-bit/pixel acceleration
 Superior performance.
32-bit direct interface with PCI bus. No external glue logic. Reduced footprint design. Cost savings.
Flexible DRAM configurations:
  • Two or four 256Kx16 DRAMs
  • Eight or sixteen 256Kx4 DRAMs
 Design flexibility for 1MB or 2MB implementations. Facilitates cost-effective graphics frame buffer solutions.
Hardware cursor (32x32x2 and 64x64x2 cursor sizes supported). No distracting cursor flicker. Improved performance.
Supports up to 16.8 million colors. Superior color display quality.
Programmable linear addressing. Eliminates bank switching.
100% hardware/BIOS compatible with IBM VGA standard. Allows use of any VGA compatible software with the video subsystem.
Multimedia Features
  • VAFC compatible feature connector
  • Overlay
  • Genlock
 Multimedia ready.
VESA Display Data Channel support. Plug and play ready.
DPMS support. Green PC compatible.

Drivers: Windows 95, NT 4.0

 

Sound Card Chipsets

***The following has been taken from Vogons and is not my own work***

The 82C928 is known to have poor Sound Blaster compatibility - cards with this audio chipset are best avoided.

Any sound card with the 82C929A chip on it is really meant for use in pure DOS or alongside another sound card in Windows. I've had greater success just running the DOS drivers (ONLY the DOS drivers) for my 82C929A-based OPTi card before completely screwing up the audio amp while trying to reverse the Stereo sound from the YMF262 (the left and right audio channels are backwards on a lot of OPTi cards with discrete OPL3).

Now, as for the distorted FM, it could be one of two things:

1) If the card uses an 82C929A or 82C930 chipset along with a real YMF262 and the op-amp right after the YAC512 is an LF347, the distortion is caused by the op-amp
2) If the card uses an 82C931 chipset, it replaced true OPL3 by what's known as OPTiFM, OPTi's piece of crap OPL3 clone

The former can be fixed by replacing the LF347 by a TL074, but the latter can't be fixed as the OPTiFM is integrated within the 82C931.

If your 82C929A has an LF347 op-amp, the sound will come out distorted unless you use the DOS drivers and don't set the mixer settings too high. The YMF262 will not distort at all if your card has a TL074 op-amp.

OPTi's earlier chips are a lot better than their later ones, mainly when it comes to OPL3. Earlier OPTi chips can have either authentic OPL3 or discrete YMF262 clones which are almost exact copies of the YMF262. Later chips like the 82C931 and the later PCI-based 82C935 (more commonly known as the MachOne EV1935) use OPTiFM, OPTi's OPL3 clone, and sound like crap as a result, though not as bad as any Analog Devices SoundPort sound card(those have the worst hardware clone of the YMF262 I've ever come across). They seem less compatible, too.

OPTi Technologies sold its audio chipset business in 1997. Please keep in mind that even prior to 1997, OPTi Technologies never made sound cards. They previously sold chips for these cards to other companies, who are responsible for providing and updating drivers. OPTi Technologies does not offer any audio drivers. If you need technical support or drivers, you will need to contact the company that made your sound card.

82C924          

Introduced: 1995
FM synthesizer: Embedded Yamaha OPL3
Plug & Play: Yes (ISA PnP)

The 82C924 audio chipset provides compatibility for Ad Lib, Sound Blaster, Sound Blaster Pro, Windows Sound System and MPU-401. It doesn't have any internal FM synthesizer or codec, instead relying on an external OPL3 such as a Yamaha YMF262 for FM synthesis, and typically a Crystal CS4231 or Analog Device AD1846 or AD1848 for Windows Sound System functionality.

Some sound cards with the OPTi 82C924 also came with an onboard wavetable in the form of OPTI's 92C941 chip.

The 82C924 was superceded by the 82C925.

Found on:

Manuals

OPTi 82C924 Product Brief
Datasheet
Application Note on Enabling Full Duplex Audio in Windows 95

 

Drivers

It is usually recommended that you use the installation software from your sound card's manufacturer, but in the absence of those, try one of these:
DOS, Windows 3.1 (1.0 MB)
Windows 95 version 4.00.10 (1.1 MB)
Windows 95 vC4.00.23 (75 KB, with DirectX support)

82C925         

Introduced: 1995
FM synthesizer: Embedded Yamaha OPL3
Plug & Play: Yes (ISA PnP)

The 82C925 audio chipset was the successor to the 82C924 and was identical in every way but now incorporated it's own FM synthesizer - an OPL3 clone called "OPTi FM". OPTi wrote at the time: "OPTiFM is the latest FM synthesis technology from OPTi that is included in the 82C925. OPTiFM (US patent pending) is not only backward compatible to the OPL3 standard, but is also enhanced to provide superior sound quality. Its unique modulation technique produces richer instrument sound, especially in percussion instruments. OPTiFM provides a more robust, crisp bass than that found in existing FM synthesis technology. In addition, OPTiFM also provides a very flexible way to assign operators and voices. This ensures complete backward compatibility and reserves plenty of room for handling future application requirements.". It had the ability to use up to 22 voices using 52 operators. For Windows Sound System compatibility cards based on the 82C925 still required a supporting codec such as the Crystal CS4231 or Analog Device AD1846 or AD1848.

The 82C925 chipset can be found on the following sound cards:

MANUALS

OPTi 82C925 Product Brief
Datasheet
Application Note on Enabling Full Duplex Audio in Windows 95

 

Drivers

It is usually recommended that you use the installation software from your sound card's manufacturer, but in the absence of those, try one of these:
DOS, Windows 3.1 (903 KB)
Windows 95 vC4.00.25 (76 KB, with DirectX support)

MAD16 / 82C928 / 82C930A 

Year: 1993
FM synthesizer: External (either true OPL3 or clone LS-212)
Chipset: OPTi 82C928 or 82C930A
IDE, Sony, Panasonic and Mitsumi CD-ROM headers
Sound Blaster Pro-compatible

MAD16 is related to the OAK OTI-601 / OTI-605 'Mozart'. The Mozart chip was co-developed by Oak Technology and Media Chip, the latter now owned by OPTi.

Reports of poor Sound Blaster compatibility on the 82C928. Also problems reported with Windows drivers on cards with this chipset. Click here for the OPTi chipset brochure from 1993.

This chipset was used on the following sound cards:

Drivers

It is usually recommended that you use the installation software from your sound card's manufacturer, but in the absence of those, try one of these:
DOS, Windows 3.1 (569 KB)
OS/2 (311 KB)
Windows NT 3.51 (89 KB)

Brochures

MAD16 Brochure from 1993

MAD16 Pro / 82C929A      

Year: 1994
FM synthesizer: External (either true OPL3 or clone LS-212)
Chipset: OPTi 82C929A
IDE, Sony, Panasonic and Mitsumi CD-ROM headers.

The MAD16 Pro is compatible with Sound Blaster Pro and WSS, has an MPU-401 compatible game port (UART mode) and supports M-CD (Media CD). It was essentially the same as the earlier 82C928 (MAD 16), but added an MPU-401-compatible UART MIDI interface and an IDE CD-ROM interface.

Click here for the OPTi chipset brochure from 1994.

Drivers

It is usually recommended that you use the installation software from your sound card's manufacturer, but in the absence of those, try one of these:
DOS, Windows 3.1 (641 KB)
Windows 95 (630 KB)

Brochures

MAD16 Pro Brochure from 1994

Datasheets

OPTi 82C929 datasheet

MAD16 Pro chipsets were found on numerous 3rd-party cards, including:

82C930       

Year: 1995
FM synthesizer: External (either true OPL3 or clone LS-212)
Chipset: OPTi 82C929A
Plug & Play: No
CD-ROM interfaces: IDE, Sony, Panasonic and Mitsumi
3D audio: No

The 82C930 is compatible with Sound Blaster Pro and WSS, and has an MPU-401 compatible game port (UART mode).

Drivers

It is usually recommended that you use the installation software from your sound card's manufacturer, but in the absence of those, try one of these:
DOS, Windows 3.1 (806 KB)
Windows 95 (628 KB)

Datasheets

OPTi 82C930 Product Brief
OPTi 82C930 datasheet

OPTi 82C931      

Year: 1996
FM synthesizer: Internal (OPTiFM)
Chipset: OPTi 82C931
Plug & Play: Yes
CD-ROM interfaces: IDE, Sony, Panasonic and Mitsumi
3D audio: No

"The OPTiSound 931 is an integrated single chip solution for multimedia PC's with full duplex stereo audio and Windows 95-compliant 16-bit Plug & Play. The 931 provides a powerful 16-bit DMA interface, 6 stereo channels, and a fully proven Soundblaster Pro and Windows sound system controller. The OPTiSound 931 offers compatibility with industrial PC audio standards, and delivers the most advanced PC audio solution for business, education, entertainment, and other multimedia applications."
OPTi website, 1996

 

The 82C931 is the successor to the 82C930, now featuring an internal FM synthesizer called OPTiFM. It is compatible with Sound Blaster Pro, WSS, has MPU-401 compatible game port (UART mode) and supports M-CD.

This chipset was used on the following sound cards:

Datasheets

OPTi 82C931 Product Brief
OPTi 82C931 Datasheet
Application Note: Enabling Full Duplex Audio in Windows 95

Drivers: DOS driver v2.03

OPTi 82C933    

Year: 1996
FM synthesizer: Internal (OPTiFM)
Chipset: OPTi 82C933
Plug & Play: Yes
CD-ROM interfaces: IDE, Sony, Panasonic and Mitsumi
3D audio: Yes

The 82C933 is compatible with Sound Blaster Pro, WSS, has MPU-401 compatible game port (UART mode) and supports M-CD.

It supports 22 voice channels, 52 operators and employs OPTi's own OPTiFM(TM) music synthesizer with enhanced bass. It also has an MPU-401 interface common for this era. It is Plug & Play so expect cards that use this to all be PnP.

It also gets a built-in third-generation 16-bit Sigma-Delta codec by ECTIVA, which is further integrated with a low distortion complex mixer featuring 3D audio expansion. The OPTiSound 82C933 produces a spatial or widened stereo image from ordinary left and right channel inputs, without any initial encoding of input signals.

As was typical for OPTi, these fully integrated chips found their way onto a number of nondescript sound cards such as this one.

82C933 Datasheet

OPTi 82C941      

The 82C941 is a wavetable synthesizer, and is simply a rebranded AdMos QDSP QS700. It is General MIDI-compatible and has 32 voice polyphony with playback at 44.1 kHz.

Support 16Mx8 memory for instrument samples which are Fat Man(TM)-certified.

Datasheets

OPTi 82C941 Product Brief

MAD32    

FM synthesizer:
Chipset: OPTi 82C950.
IDE, Sony, Panasonic and Mitsumi CD-ROM headers.

Click here for the OPTi chipset brochure from 1994.