Document: PCI chipsets list Maintainer: Patrick Duffy, duffy@theory.chem.ubc.ca Revision Dates: 11/5/95, 11/26/95, 12/3/95, 5/18/96, 5/26/96, 6/2/96 Archived at: ftp.netcom.com, in directory /pub/ab/abe/ CompuServe (GO BENCHMARK) Web pages: http://warp.eecs.berkeley.edu/os2/workbench/work.htm http://www.os2forum.or.at/english/info/os2hardwareinfo/ (note that the first URL may not have up-to-date versions of the lists) This document is intended for use by individuals and corporations in a non-commercial manner. It may be distributed freely within those limitations. Commercial use of this document in any manner requires prior written permission of the author. Here follows a brief summary of PCI chipsets. I've tried to keep it accurate, but if you spot any flaws please feel free to correct me, and if you have details on other chipsets, please feel free to let me know about them. I've included information at the end of this list to help people ID the chipset (assuming they have an Intel chipset on their motherboards). Where I know for sure that they do, I have indicated that a chipset will use parity RAM. PCI Vendor IDs first in HEX then in decimal appear in brackets beside the chipset names. Dates in brackets indicate the last revision date of the related entry. NEW THIS WEEK ------------- I've corrected the cache timing information for the 430HX and 430VX chipsets. I've also expanded on the PCI 2.1-compliance of these chipsets a little. The ALI chipset is now at revision A1 and appears to be O.K.. I've also updated the Neptune chipset parts list, as it seems that there is more than one possible configuration for it. New and expanded contact information for Intel has also been added. Useful numbers: (6/2/96) -------------- ALI: (408) 764-0644 (sales) Intel: (800) 628-8686 (tech. support) FAXBack: -------- (800) 525-3019 (US or Canada) +44 1793-432509 (Europe) +65 256-5350 (Singapore) +852 2 530-4116 (Hong Kong) +886 2 514-0815 (Taiwan) +822 767-2594 (Korea) +61 2 975-3922 (Australia) (503) 264-6835 (World wide) BBSes: ------ (503) 264-7999 (US or Canada/World wide) +44 1793-432955 (Europe) +65 256-4776 (Singapore) +852 2 530-4116 (Hong Kong) +886 2 718-6422 (Taiwan) +822 784-3430 (Korea) +61 2 975-3066 (Australia) ftp.intel.com (FTP site) www.intel.com (WWW site) OPTi: (408) 486-8000 (voice) http://www.opti.com (WWW site) VIA: (510) 683-3300 (voice) (510) 683-3301 (FAX) (886) 2-218-5452 (Taiwan voice) (886) 2-218-5453 (Taiwan FAX) http://www.fic.com.tw (WWW site) PART ONE: 80486 Chipsets ------------------------- 1) The Aries Chipset (Intel: 8086/32902) (10/31/95) ----------------- This is a chipset made by Intel for 80486-based machines, and used in boards (such as the Asus AVP4) where PCI and VL buses are to coexist. Unlike the Contaq chipset below, the Aries chipset implements PCI using a PCI to CPU bridge, and the VL bus is attached to this. This allows for full PCI performance, though I don't know what effect it has on VL (which likely will run no faster than the 33 MHz at which PCI 2.0 runs). The chipset has apparently been through at least two revisions, at least one of which has problems with protected-mode code and zero wait-state cache operation. (This may be worked around via the system BIOS by setting the cache so that it uses 1 wait state for its operations.) This chipset has reportedly been discontinued. 2) The Contaq Chipset (Contaq: 1080/4224) (8/27/95) ------------------ The Contaq 82C599 is paired with one of their 486VL chipsets (82C596 or 82C597) and bridges directly from the 486 CPU to the PCI bus. Paraphrased from the Contaq spec.: The 82C596 system controller provides the CPU interface, VESA bus interface, ISA bus controller, etc. The 82C599 PCI controller provides the bridge between PCI master/slave agent and the ISA/VESA standard expansion bus; it arbitrates all the bus transactions between host CPU, PCI agent, VESA device, and ISA device. (Which sounds to me like the PCI bus is attached to the VL bus, rather than to the CPU, which will cause PCI performance degredation.) 3) The FINALI-486 Chipset (Acer Labs: 10B9/4281) (6/2/96) ---------------------- This is ALI's chipset for 486 systems, consisting of the M1487 and M1489 chips. It supports EDO RAM and all the different 486 CPUs, and has IDE, a real-time clock, and a keyboard controller. The A1 revision of this chipset apparently causes no problems for OS/2. Apparently ACER 486's which use the board usually have slow cache controllers. Use CTCM to check your board's performance. 4) The Opti Chipset (Opti: 1045/4165) (8/27/95) ---------------- Components: 82C822 (PCI functions) 82C895 (all other functions) This is Opti's chipset for 486-based machines. It's reported to work well with OS/2, although it implements PCI using a VL-to-PCI bridge instead of the other way around. Apparently this chipset will only allow 1 32-bit burst transfer per bus arbitration cycle, which limits throughput to 8 MB/s instead of (the maximum ideal transfer rate of) 132 MB/s. Boards which use this chipset are, therefore, to be avoided. 5) The Saturn Family of Chipsets (Intel: 8086/32902) (8/27/95) ----------------------------- The Saturn family of chipsets is designed for use exclusively with 80486 and compatible processors, up to DX4s. They will, as of the latest revision, work with the P24T Pentium Overdrive processor. Boards which use them typically are of the combination ISA/PCI type, as I do not believe the Saturn chipsets were designed to handle VL extensions. The Saturn chipset has been through three revisions, numbered (oddly enough) 1, 2, and 4. Some brief comments on each: Rev. 1: Is now long-since discontinued. This chipset will only appear on older motherboards (perhaps pre Jan. '94?), and should not be on any motherboards of recent vintage. This chipset had problems (unknown to me), and so was put through its first revision and re-released. Rev. 2: Is still in wide use. This chipset has problems with cache integrity during PCI to CPU burst mode operations, as well as certain SCSI operations. Any board which uses this chipset today will still have these problems. There are BIOS "fixes" provided by various manufacturers, but what these usually do is disable the high-performance options on the chipset. Rev. 2 was never 'fixed', and there is no such thing as a newer release called rev. 2. Because of the bugs, however, a new version of the Saturn chipset was released. Rev. 4: With this release of the Saturn chipset, Intel seems to have finally fixed the problems with the earlier revisions. This chipset (also called Saturn II) also supports all the green features when used in combination with the right BIOS. It is distinguished externally from its older cousins by the last two letters on one of the three chips. Check for a 'ZX' to positively identify the Saturn II chipset. This chipset, when presented with a device which transfers 100 Mb/s, doesn't seem to let the CPU run at all. 6) The SIS chipset (Silicon Integrated Systems: 1039/4153) (9/20/95) --------------- Components: 85C496 and 85C497 SIS makes a separate chipset for 486-based boards which is commonly used in systems which also have VL slots. Unfortunately, it sounds as though the chipset implements PCI by bridging it to VL (instead of the other way around), so PCI-based systems which have VL slots will suffer a degredation of PCI performance. Still, however, boards manufactured by AMI and Asus have been reported to work well with OS/2. There have been five revisions of this chipset. A4 (the earliest one) supports IDE up to mode 2 but apparently was not stable with caches on. B2 had on-board IDE support but did not support mode 3 well. Revisions B3 and later apparently work better. The varisous chipset revisions can be identified by their labels: A4 Version chipset: SIS 496 MU, SIS 497 MW B2 Version chipset: SIS 496 NU, SIS 497 NS B3 Version chipset: SIS 496 NV, SIS 497 NS B4 Version chipset: SIS 496 NV, SIS 497 NU B5 Version chipset: SIS 496 OR, SIS 497 OT 7) The UMC chipset (United Microelectronics: 1060/4192) (9/13/95) This chispet consists of the 8881 and 8886 chips, currently seeming to be at revision F. I've no other specifics on this chipset, though boards designed with it appear to be relatively stable. 8) The VIA GMC chipset (VIA: 1106/4358) (5/18/96) -------------------- This chipset includes the VIA VT82C486A-F with a built-in 8042 keyboard controller and a VIA VT82C505-D chipset for the VESA to PCI bridge. Specifically, the chips are as follows: 82C486A - cache/memory controller + VLB to ISA bridge 82C482 - VLB to ISA bridga (why there are two I'm not sure) 82C483 - DRAM controller VT82C505 PCI to VLB bridge A board using this chipset has been unstable (even under DOS/Win), and did not work with an Adaptec 2940 SCSI controller under OS/2 at all. Boards based on this chipset are therefore to be avoided. I have, however, had one report of success from someone using revision G of this chipset, so it could be that the new revision fixes problems with older rev's. Designers with whom I've corresponded indicate that improperly designed boards which use this chipset may have unstable caches. In addition, the cache controller reads the data into the cache SRAMs first, then into the CPU, increasing latency and reducing throughput. PART TWO: Pentium Chipsets --------------------------- 1) The Aladdin Chipset (Acer Labs: 10B9/4281) (8/27/95) ------------------- This is a chipset (M1511/12/13) which supports Intel, AMD, and Cyrix CPUs. It has an advanced programmable interrupt controller, supports dual processors, all the different RAM and cache options, and includes an IDE controller which busmasters. I've no reports of success or failure with OS/2 and this chipset, and apparently early versions of this chipset had a cachable DRAM size of only 32 MB. 2) The Ariel Chipset (Intel: 8086/32902) (8/27/95) ----------------- This is Intel's chipset for notebooks. It has most of the same features as Triton (below) and supports all the advanced power management features common to notebooks. 3) The Genie Chipset (Acer Labs: 10B9/4281) (8/27/95) ----------------- This is a chipset by Acer Laboratories Inc. (ALI) which is intended for use in multiprocessing systems. Specifically, the chipset will support up to four P54C, P55C, Cyrix M1 or AMD K5 processors, though I don't know if you can "mix and match" the CPUs (though I doubt it). I've had no reports of success or failure with boards which use this chipset. 4) The Mercury Chipset (Intel: 8086/32902) (5/18/96) ------------------- The Mercury chipset is designed for use primarily with 60 and 66 MHz Pentium processors (so you won't see 486 motherboards with it, and you usually won't see 90/100 MHz boards with it either, though there are always exceptions). It has, apparently, been through two revisions as well. The first revision is reported to have the same problems with posted buffered writes as Neptune I. This problem was fixed in Mercury II. This chipset will use parity RAM. This chipset also has the problem that if you use a busmastering PCI SCSI controller and an EISA busmaster networking card, the system will lock up. The only solution to this problem is to have both your networking card and your SCSI controller use the same bus (whether EISA or PCI). 5) The Neptune Chipset (Intel: 8086/32902) (6/2/96) ------------------- Components: 83434NX (PCI/cache/memory controller) 83433NX (local bus extension devices) 82378IB-G or 823783B (system I/O bridge chip) The Neptune chipset is designed for use with 75, 90 and 99 MHz Pentium processors (so you won't see 486 motherboards with it, or 60/66 MHz boards with it either). It has support for SMP as well, and so is used in all SMP systems to date. The Neptune chipset has been through two revisions, both of which will use parity RAM. Rev. 1: This chipset was in boards shipped by Intel to vendors up until about the end of July 1994. It has/had problems with posted buffered writes, which would manifest themselves most prominently with SCSI devices (which used this feature extensively). Recent releases of the AMI flash BIOS which Intel ships with their Premiere II (90/99 MHz) boards (the latest is 1.00.13.AX1) switch posted buffered writes off on the chipset when rev. 1 of the chipset is detected. Rev. 2: This chipset is in boards shipped by Intel to vendors as of about mid August 1994. It has no reported problems (and works well in my system). Both revisions of this chipset, like the Mercury chipset above, also have the problem that if you use a busmastering PCI SCSI controller and an EISA busmaster networking card, the system will lock up. The only solution to this problem is to have both your networking card and your SCSI controller use the same bus (whether EISA or PCI). 6) The OPTi chipsets (OPTi: 1045/4165) (11/26/95) ----------------- There are three OPTI chipsets in use: One is used in Pentium boards which also have a VL bus. This from the OPTI spec. sheet (paraphrased): One of the other OPTi chips provides CPU interface, VESA bus interface, ISA bus controller, etc. The 82C822 PCI Bridge bridges between the ISA/VESA and the PCI; it arbitrates the bus requests between host CPU, PCI masters, DMA/ISA masters, and Refresh. (The other chips in the chipset are the 82C596 and 82C597.) This chipset is reported to yield very poor VL/PCI performance, as an asynchronous clock is used for the local bus, resulting in synchronization delays. Apparently CPU/cache performance is acceptable. (Which again sounds to me like the CPU is hooked up to the VL bus and the PCI is bridged to that.) There is apparently a problem with this chipset which causes the BusLogic and Adaptec SCSI adapters to not work properly, as the PCI controller is not being properly programmed. The other OPTI chipset is apparently new and nicknamed "Viper". It consists of the 82C556 (data buffer controller), 557 (system controller), and 558 (peripheral controller) chips. It supports busmastering IDE and type F DMA, and Intel's Native Signal Processing (NSP), which means that it will allow the Pentium to perform DSP functions. It also supports all the latest power management features, and has the ability to run the PCI bus at 33 MHz irrespective of processor speed. It supports all the Pentium and Pentium-like processors (up to 100 MHz), as well as EDO and normal DRAM (up to 512 MB), and all everything up to pipelined burst cache (up to 2 MB). I've no reports of success with this chipset and OS/2. There is a notebook variant of this chipset (an "N" is suffixed to the chip model numbers above) which supports all of the same features. Opti also has a third chipset in the Viper series, the Viper-UMA. This chipset apparently supports all the features of the Viper above, with the addition of one or two special features: 1) Support for Burst EDO (BEDO) RAM and synchronous DRAM. 2) Unified Memory Architecture (UMA in the name). This apparently combines memory on video adapters with main memory, and allows peripherals direct access to it. 3) Support for real 132 MB/s PCI data transfers. Apparently the BusLogic SCSI controller has difficulty with the earlier the OPTI chipsets, in that the chipset can generate spurious interrupts, causing the card to not claim interrupts that it should. There is apparently a workaround for this in the latest BusLogic driver. 7) The Samsung chipset (Samsung Electronic Co., Ltd.: 1099/4240) (8/27/95) ------------------- Samsung makes a three-piece Pentium chipset. The KS82C531 is the cache (it will support synchronous caches) and RAM controller (EDO or DRAM). I've no more details on the chipset, nor reports of any success with it and OS/2. 8) The SIS chipset (Silicon Integrated Systems: 1039/4153) (11/26/95) --------------- SIS makes a chipset for Pentium-based PCI motherboards which will apparently support (with the right BIOS) some non-spec. PCI operations. There are settings, apparently, which will allow the PCI bus to run at CPUCLK/1.5, which means that for a 90 MHz CPU (60 MHz external clock), you could run your PCI bus at 40 MHz. What affect this has on everything else remains to be seen, but the chipset is reported to work well with the Asus motherboard which uses it. There are in fact two versions of the SIS chipset. The earlier one, 550X, did not support EDO RAM, pipelined burst cache, or on-board IDE. The newer chipset, 551X, apparently does. It is reported to work well. 9) The Symphony "Rossini" Chipset (Symphony Labs: 10AD/4269) (9/13/95) ------------------------------ This is apparently a low-cost alternative to the Triton chipset, as it operates with up to 66 MHz external clock rates, up to two CPUs, piplined or non-piplined, synchronous or [conventional] asynchronous SRAM cache, EDO RAM, and does dual-port busmastering IDE. It will, apparently, adjust the voltages to its various (CPU, PCI, cache, RAM) buses to suit their requirements, and will control up to six PCI masters. It consists of the SL82C551 cache/memory controller, the SL82C522 data path controller, and the SL82C555 system I/O controller. 10) The Triton Chipset (Intel: 8086/32902) (12/3/95) ------------------ Components: 82437FX System Controller 82438FX Data Path 82371FB PCI ISA IDE accelerator This is the latest PCI chipset to come out from Intel, and is PCI 2.1-compliant. It will also increase PCI-to-memory bandwith from 40 MB/sec (in Neptune) to 100 MB/sec, and features an enhanced ISA bridge and built-in EIDE support. Drivers for all major operating systems to take advantage of the busmastering capability of the Triton chipset may be found in the file called triton.exe (or triton.zip), available at all the major OS/2 FTP sites. (Note that one person has reported that his system locks when using this driver in combination with fixpack 9). It also supports EDO RAM, which will allow access to RAM in a 3-2-2-2 burst rather than the conventional 7-4-4-4 burst. There is also now a 12 word buffer between the PCI bus and memory as opposed to the 8 word buffer in Neptune. The chipset does not check parity, although parity RAM may be used (without any benefit) in systems which use the chipset. Systems which use the chipset appear to run OS/2 very well. It would seem that there may be (soon if there isn't already) more than one version of this chipset. Early versions of the chipset are reported to have (unspecified) problems with Matrox and (some) Diamond Stealth cards. (These problems appear to be video card-related and nothing to do with Triton.) Chipset limitations: -------------------- Triton I will not cache more than 64 MB of RAM. Triton I also has the following (rather serious) drawback when its IDE features are used in a multitasking environment (this paraphrased from the Intel spec.): First of all, the Triton chipset has only a single bus for its two IDE channels. This means that only one IDE device may be active at a time, even if you have them on separate channels. Second, it also shares this data bus with the ISA address/data bus function that is also in the chip. This means that if you have your serial or parallel ports on the Triton ISA bus (as most motherboard designs do) and you have any COM or LPT activity going on this will be multiplexed with your two ATA interfaces on the same set of signals comming out of the Triton chip. This limitation affects any devices on the ISA bus, actually. This could really bring multitasking to a crawl if you have a disk-intensive program going and you're trying to download something in the background (or, for that matter, even use a serial mouse). Intel claims "fair round robin" sharing of all the uses of the single bus, however. 11) The Triton II (430HX) Chipset (Intel: 8086/32902) (6/2/96) Components: 82439HX (System controller) 82371SB (IDE controller) This chipset, according to people with whom I've spoken at both AMI and Intel, is not so much a revision level of Triton I but a redesign of the Neptune chipset. This is supported by the fact that the cache timings in this chipset (3-1-1-1) are no faster than in Triton I (though it is perceived to be a better chipset otherwise than is Triton III, which does 2-1-1-1). This chipset supports: 1) Caching of RAM up to 512 MB. 2) Support for SMP (up to 4 processors). 3) Support for parity/ECC RAM. 4) Full PCI 2.1 bandwidth capabilities. If you have all 2.1-compliant cards capable of running at 66 MHz, this chipset is capable of running your PCI bus at up to 66 MHz (if your motherboard design also supports it). 64-bit PCI is also supported (if your motherboard implements it). 5) Concurrent PCI operation. If you have more than one CPU and more than one PCI bus on your motherboard, the chipset is capable of allowing both PCI buses to be accessed simultaneously. 6) Support for the Universal Serial Bus. This allows daisy-chaining of (say) a mouse from a keyboard instead of having them both plugged into the back of your PC. It sounds very SCSI-like. I don't believe there are any USB peripherals out yet, though. I don't know if they've done anything about the common data line for the IDE I/O and the ISA bus, though. Given the concurrent PCI implementation, however, it seems likely. This chipset has been through four revisions: A0: Initial release. A1: Fixed a bug in A0 with ECC RAM. B1: Added two-way SMP. B2: Added USB support. 12) The Triton III (430HX) Chipset (Intel: 8086/32902) (6/2/96) Components: 82437VX (System controller) 82371SB (IDE controller) 82438HX (Data path unit) This chipset, "optimized for home use", apparently, is compatible with Triton I but supports faster cache timings (2-1-1-1) than does Triton II. It uses Unified Memory Architecture (UMA), which means that your video card shares some of the motherboard memory with your CPU. This is supposed to slow things down, or so I'm led to understand, though I don't know why. 13) The VIA Apollo Chipset (VIA: 1106/4358) (12/3/95) ---------------------- Components: VT82C575M, VT82C576M, VT82C577M, VT82C416 (four chips) This chipset by VIA is unique in my experience in that it supports all of the following: 1. Burst Synchronous and Pipeline Burst Cache 2. Standard and Burst EDO RAM 3. Pentium, K5, M1 CPUs 4. 4-level CPU to DRAM write buffer 5. 32-bit and 64-bit DRAM 6. Integrated EIDE controller (unspecified, though I think it busmasters) 7. notebooks and desktop machines 8. Plug and Play (version unspecified) 9. PCI NSP I've had a report of (relative) success from one person using this chipset and OS/2, though there are also (with that same board) unspecified BIOS problems. 12) The Wild Cat chipset (VLSI Technology Inc.: 1004/4100) (5/26/96) -------------------- This is a chipset by VLSI. It will handle EDO RAM, drive DRAM chips and some ISA slots without external buffers, byte merging (for writes), and has the ability to read data from the 64-bit data buffer without first writing it to memory. It will support all the AMD and Cyrix chips as well. I've had one reports of success with this chipset and OS/2 2.11 SMP. The performance of the chipset is reported to be better than Neptune II but not as good as Triton. PART THREE: P6 Chipsets ------------------------ 1) The Mars (450KX) Chipset (Intel: 8086/32902) (5/26/96) ------------------------ This is a chipset by Intel which supports many of the same features as the Triton chipset (except that it also supports parity checking). It will be the general purpose chipset for use with mainstream PCI P6 motherboards. 2) The Mercury Chipset (Opti: 1045/4165) (8/27/95) ------------------- This is a chipset by OPTI. 3) The Natoma (440FX) Chipset (Intel: 8086/32902) (5/26/96) -------------------------- Components: 82441FX PCI and memory controller 82442FX Data bus accellerator 82371SB PCI ISA IDE accellerator 82093AA Standalone I/O APIC component (optional -- for two-processor designs only) The Natoma chipset competes with Orion. It has a couple of reduced capabilities, in that it supports up to two CPUs and not four (Orion supports four) and it will not do four-way interleaving of RAM (Orion does). However, it takes fewer chips (three) than does Orion. 4) The Orion (450GX) Chipset (Intel: 8086/32902) (5/26/96) ------------------------- Orion is a six- to nine-chip set (depending on the implementation) by Intel. It supports multiprocessing, up to four memory interface controllers (each of which can support up to 1 GB of DRAM), and the new 64 MB DRAM chips. This chipset will be used in higher-end systems (with prices to match). This chispet has been through a number of revisions. Here's what I know about them: A0: Initial release. A1: Fixed a bus bandwidth speed flaw in A0. A2: Apparently turning on write posting in this revision can cause severe data corruption. B0: Fixed write posting bug in A2. 5) The VIA Apollo Pro Chipset (VIA: 1106/4358) (12/3/95) -------------------------- This chipset (VT82c695 system/PCI controller and VT82c685 super I/O controller) competes with the Intel Natoma chipset and adds the following features: - only two chips required - support for synchronous DRAM Useful Information: (12/3/95) ------------------- How to find out your motherboard PCI chipset type and revision: (Requires DOS support to be installed, and does not appear to work for all machines.) THE FOLLOWING INFORMATION IS SUPPLIED WITHOUT ANY WARRANTY, EITHER EXPRESS OR IMPLIED, OF ANY KIND. UNDER NO CIRCUMSTANCES MAY I (PATRICK DUFFY) BE HELD LIABLE FOR ANY DAMAGE RESULTING FROM USE OF THE INFORMATION GIVEN BELOW. YOU (THE READER) ASSUME FULL RESPONSIBILITY FOR ITS USE AND THE CONSEQUENCES THEREOF. The following commands will identify various aspects of your motherboard PCI chipset. Type each command as it appears (and press enter, of course). I've tested this on my own motherboard and it seems to work. Under the result column, '-' means that nothing will be shown. I do not know what the result codes will be for the Contaq or Aries chipsets, so please feel free to let me know. Command Result Comments debug Enter debug. O CF8 F0 - Open PCI interface. I C000 86 Chipset manufacturer ID: `8086' means I C001 80 Intel, any other value implies the other bytes are nonsignificant. I C002 DeviceID_LSB I C003 DeviceID_MSB Chipset's ID I C008 RevisionID Revision number O CF8 00 - Close PCI interface quit Exit debug. The chipset's ID can be 0483 (Saturn), 0486 (Aries), 04A3 (Mercury/Neptune), or C557 (OPTI Viper). For the Saturn chipset, revision 1/2 is for Saturn I, rev. 4 is Saturn II. For Mercury/Neptune: revision 1/3 is for Mercury I/II, and revision 10/11 is for Neptune rev. 1/2. The Triton chipset appears to ignore this query. The System Information tool available in Warp provides a much more elegant way to ID your Triton chipset (and, for that matter, every other PCI peripheral on your motherboard). The Triton chipset's ID is 122D, revision 0001 for the 82437FX, and 122E, revision 0002 for the PCI/ISA bridge. How to identify which revision of the SIS 486 chipset you have: There are five slightly different revisions of the SIS chipset used: A4, B2, B3, B4, and B5. The A4 does not have onboard ide support. All the B-level chipsets do, however, with B5 being the best chipset to have. The various chipset revisions can be identified by their labels: SiS 85c496 MU & 85c497 MW (A4) SiS 85c496 NU & 85c497 NS (B2); SiS 85c496 NV & SiS 85c497 NS (B3); SiS 496 NV & SiS 497 NU (B4); and SIS496 OS and SIS 497 OT (B5). So that's what I know, as clearly as I know how to say it. If you have any questions or notice any ambiguities please do let me know and I'll do my best to correct them. -- Patrick Duffy, duffy@theory.chem.ubc.ca "Evil is out there making hand-crafted mischief for the swap meet of villany." -- The Tick