The Ultimate Museum PC

While the OS/2 Museum employs modern computers and virtualization heavily, sometimes there is a need for good old hardware—emphasis on good and old. A virtual machine won’t read 5¼” floppies and there’s no way to plug in a real Sound Blaster AWE32 or an Adaptec 1540CF.

There is a definite need for an old system, yet at the same time the system should not be too slow and too limited. Indeed there are conflicting requirements: The system should be fast, have lots of RAM, a big disk, yet needs to support ISA slots and 5¼” floppy drives. An AGP slot is a must. The system should also be maximally stable and compatible. If at all possible, the system should support SMP (likely a dual-processor system).

The stability and compatibility requirement favors an Intel CPU and an Intel chipset. The objective is not the best bang for the buck (any hardware that old is likely to be cheap, if not free), the objective is a system that works.

The Chipset

If Intel chipsets (and CPUs) are taken as a constraint, the chipset choice is surprisingly limited. A brief look at the list of Intel chipsets reveals that there are rather few candidates; the 810/820/815 chipsets removed ISA support, which leaves the older 440/450 generation. The 440MX is mobile only, 440ZX is just slightly crippled 440BX (no SMP support, fewer memory slots). The 450NX is a server chipset which supports up to 8GB RAM(!) but does not support AGP and cannot use SDRAM. That leaves 440BX and 440GX. The latter was used mostly in server-oriented motherboards and there are extremely few suitable candidates.

The 440BX (Seattle), on the other hand, was one of Intel’s most popular chipsets ever, perhaps slightly better than Intel intended—and preferred by many to its designated successors (the 810 and 820 chipsets). It was a high-end yet not particularly expensive desktop chipset; indeed some even say that “something went horribly right at Intel when the 440BX chipset was designed”. The motherboard choice is extremely broad, with both single- and dual-processor boards.

The 440BX supports up to two processors, 1GB RAM, Ultra DMA/33, EDO or SDRAM DIMMs, AGP 2x, and 66 or 100MHz FSB (with CPU and memory running at the same FSB frequency).

The Processor

The choice of processor is trickier. The 440BX/440GX chipsets support Pentium II, Celeron, and Pentium III CPUs with FSB speeds up to 100 MHz, but do not support the faster Pentium III processors (at least not officially or not without some sort of hardware hackery). Then again, a 400-600 MHz processor should be just fine for the purpose.

The processor choice is tied to the motherboard’s slot or socket type. 440BX-based motherboards supported Slot 1 or Socket 370, either in single or dual configurations. Pentium II processors and early Pentium IIIs (Katmai) were all designed for Slot 1, while most Celerons and later Pentium IIIs (Coppermine and Tualatin) used the Socket 370 form factor.

440BX Slot 1 motherboards don’t support the newer Pentium III models, and neither do the older Socket 370 boards; the problem is lower voltage (which requires hardware shims) as well as BIOS support (sufficiently uptodate BIOS required).

Then again… perhaps the CPU speed doesn’t matter that much. After all, the machine isn’t supposed to run Windows 8—it needs to run OS/2, DOS, Windows 2000 or Windows XP, perhaps Windows 98, probably Linux.

The Default Choice: ABIT BP6

It just so happens that I’ve owned one of the famous ABIT BP6 boards since 1999. It was my main system for a while, relatively soon replaced by a 600 MHz Pentium III with the 440ZX chipset.

The BP6 is best known as the first board which supported SMP configurations with Mendocino Celeron PPGA processors, something that was not possible according to Intel. Those Celerons were a little like the 440BX chipset—perhaps a little better than Intel intended. Based on the Pentium II core, the Mendocino Celerons had only 128KB L2 cache (vs. 512KB on the “real” Pentium IIs), but running at full CPU speed rather than half-speed as the Pentium II’s L2 cache did. As a result, the Mendocino Celerons had an interesting profile, being either faster or slower than a Pentium II at the same frequency, depending on whether the task at hand benefited from the larger cache or not (the majority did).

After years of neglect, the BP6 was resurrected and reinstated into OS/2 Museum service. It is currently equipped with two 533 MHz Mendocino Celeron CPUs, the fastest the board supports without any hacks or overclocking. Memory has been upgraded to 640MB (the maximum is 768MB, with 3 slots).

BP6 Pros

The BP6 fulfils most of the requirements: it sports two ISA slots, an AGP 2x slot, and five PCI slots. It has the usual PS/2 mouse and keyboard connectors, two serial and one parallel port. Best of all, it includes the Intel 82093AA I/O APIC and runs SMP operating systems (OS/2, Windows XP, Linux) very well.

The BIOS (AWARD 4.50) implements proper 5¼” floppy drive support, which is something more recent BIOSes often lack.

The system is very stable and quite a decent performer. It’s equipped with a 120GB Western Digital disk and a Radeon 9200 AGP graphics card. The graphics card was chosen as one of the very few AGP models available around 2010 with both a DVI and a VGA connector.

BP6 Cons

It’s not all roses of course. The biggest drawback of the BP6 is that it doesn’t natively support anything faster than those 533 MHz Mendocino Celerons. It is possible to install newer CPUs with various adapters, but usually at the cost of a loss of SMP functionality. That’s not worthwhile.

Since the 440BX chipset only supports Ultra DMA/33, the BP6 designers thought it’d be nice to put a HighPoint Ultra DMA/66 IDE controller on the motherboard. Sadly, the controller isn’t supported in Windows 2000 and later, which makes it useless (and the Ultra DMA/33 performance is quite sufficient anyway). The standard BIOS does not have an option to disable the HighPoint controller, just to increase the annoyance.

A minor issue is that the BIOS can’t support IDE disks larger than 128GB. For this system, the current 120GB disk is more than big enough.

Can We Do Better?

Is there a better board out there? Probably. But to make an upgrade worthwhile, the replacement would have to support two Pentium III CPUs at 700+ MHz (with 100MHz FSB). That does not leave a lot of candidates. Perhaps a Tyan Tiger 100? An EPOX KP6-BS? A Soyo SY-D6IBA? A Gigabyte GA-6BXD? A DFI P2XBL/D? An Iwill DBD100? With most of these boards, it is quite difficult to determine the fastest supported CPU model.

There are various server-oriented boards (some built around the 440GX), but most of those aren’t too attractive. Integrated SCSI controllers or graphics cards are more of a drawback as the OS/2 Museum already has a decent collection of SCSI adapters and graphics cards, many of them better than what’s integrated on those boards. Many have just a single ISA slot, which is again a minus. 2GB RAM capacity isn’t that much of a big deal (compared to 1GB which the desktop board support).

Any suggestions, dear readers? Is there a vintage board which is in all respects at least as good or better than the BP6?

Addendum

After some research, it looks like Slot 1 is indeed the way to go. Should the need arise, there are “slockets” for installing PPGA processors in Slot 1 boards, whereas no such device exists for the opposite direction. Slot 2 (Xeon) seems too exotic with questionable performance benefits (as those Xeons didn’t seem to be available in speeds over 700 MHz or so). It should be possible to install dual 1 GHz Pentium IIIs (Coppermine with 100 MHz FSB) in the right boards.

The top candidates currently are ASUS P2B-D (Rev. 1.06) and Tyan Tiger 100 (Rev. F). Both are reasonably easy to find, though it is often tricky to determine whether it’s the right revision with Coppermine CPU support. The Supermicro P6DBE and Gigabyte GA-6BXD also sound promising. All of these should be superior to the BP6 with the appropriate CPUs.

Curiously, the ASUS P2B-DS with on-board SCSI appears to be the easiest to find. I’d prefer the SCSI-less variant since a) I have a spare Adaptec 29160N anyway, and b) I often need to plug in a different SCSI HBA for testing. That said, SCSI would be the obvious way to work around the 128GB IDE limitation typical for these systems, should 120GB prove insufficient.

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20 Responses to The Ultimate Museum PC

  1. Peter Godwin says:

    ISA Socket 370 options are quite limited. There are plenty of Slot 1 options however. I recall working on a machine with an ASUS P2B-D for quite a while, but I’m not sure how you’d go about tracking one down.

  2. Yuhong Bao says:

    You may also want to look at VIA Apollo Pro 133A chipset, which has 133MHz support, supports SMP with an APIC too. Drawback is only one ISA support typically.

  3. Yuhong Bao says:

    Sorry, only one ISA *slot* typically.

  4. michaln says:

    I’m aware of it, but in light of my past experience with VIA (largely negative) I’m rather skeptical. I also doubt the 133MHz vs. 100MHz FSB makes that much of a difference in the overall picture. A single ISA slot would not be a deal-breaker but it is a minus.

  5. michaln says:

    How to find one might be a challenge, but the P2B-D sounds good. According to ASUS the newer revisions should support up to 1GHz processors. I see it only has 4 PCI slots but then again the 5-slot boards usually have one shared with ISA, so it’s a wash.

    The Tyan Tiger 100, which also looks promising, is only listed to go up to 850 MHz; then again forum chatter suggests it actually can work with 1GHz PIIIs as well.

    For both the ASUS and the Tyan it seems the board revision needs to be sufficiently high to support the faster Coppermines.

  6. Yuhong Bao says:

    Another benefit of the 82093AA and newer APICs is separate lines for edge-triggered ISA and level-triggered PCI interrupts.

  7. michaln says:

    You’re making it sound like the I/O APIC has different inputs for ISA and PCI interrupts, when it simply has (typically) 16 or 24 configurable interrupt lines. Yes, the usual, but far from the only possible, wiring is such that the PCI interrupts are connected to the last 4-8 I/O APIC inputs and the ISA devices take up the first 16.

    And yes, I’m sure this does improve things a bit in the typical system, especially when the alternative is squeezing all PCI interrupts onto IRQ 11 or something silly like that. The worst case behavior has to be pretty bad. The I/O APIC should help a lot, unless the system designer managed to connect all PCI devices to the same PCI interrupt anyway 🙂 (Not likely!)

  8. Dale Smoker says:

    Would NT 3.1 run in multiprocessor mode on these boards?

  9. michaln says:

    I don’t think NT 3.1 shipped with a HAL for the Intel MPS, just some custom AST/NCR/Olivetti/Compaq/Wyse stuff. Not surprising since the MPS 1.1 spec was published in Sept ’94. NT 3.5 was the first to ship with HALMPS.DLL. It might work on these boards. Do you want me to find out if it does? 🙂

  10. Dale Smoker says:

    Sure 🙂

  11. ampharos says:

    Darn, just passed up a Tyan Thunder LE that came with dual 1 Ghz Coppermines, dual networking, an 512 MB of ECC SDRAM.

    I’m kicking myself right now.

  12. michaln says:

    No ISA slots -> not interesting for me 🙂 But it looks like a very nice board.

  13. ender says:

    You might find this board interesting: http://www.msi.com/product/ipc/MS-98A9.html
    It’s a Sandy Bridge board with (optional) ISA slot (and 5 PCI slots).

  14. Michal Necasek says:

    Very nice, but no floppy support, that kind of sucks…

  15. Claude Herail says:

    The AxiomTek IMB200. That could be interesting to you if you can ever find one. It supports floppy drives, AGP and has ISA support, probably the only LGA775-pin motherboard in the world which does. And you could use it with a 3.8GHz Pentium 4 … : “The IMB200 supports LGA775-pin Intel® Pentium® D, Pentium® 4, and Celeron® D processors with a 533/800MHz FSB, and features an Intel® 865G+ICH5 chipset. Two 184-pin dual-channel DDR DIMM sockets on the IMB200 have a maximum memory capacity of 2GB. VGA function with Intel® Extreme Graphic 2 Technology is built into the Intel® 865G chipset which delivers powerful 2D/3D graphics performance. The IMB200 also offers Intel® 82547GI Gigabit Ethernet controller and Intel® 82562ET Fast Ethernet controller to provide perfect network connectivity. The IMB200 provides five PCI slots, typically required in applications where a large number of peripheral cards are installed. It is compatible with ISA DMA and non DMA mode cards by PCI-ISA Bridge for extending ISA add-on cards. The IMB200 is specially suited for the solutions which need more effective computing and reliability, such as Digital Video Recorder, Gamine Machine, Point of Service (POS) System, Video Server, and Intelligent Transmit System. ” I found one on eBay, I’ll be trying it next month.

  16. Michal Necasek says:

    Please report your experiences 🙂 I’m a bit skeptical about running DOS on such a system… it seems too fast. Also Pentium 4 is one of the worst Intel CPUs ever. But for maximum performance in an ISA capable system, this may well be the ticket.

  17. Claude Herail says:

    These days I run DOS on a Gigabyte GA-8I875 with a 3.4 GHz Pentium 4. It doesn’t have any ISA slots but the speed is not a problem for DOS – except I’m sure with some games, nor is the ridiculous amount of RAM (2.5 Gb), with a good memory manager like QEMM. The reason for the Pentium 4 and the RAM is that I tried to build a system that would run every version of Windows from 3.11 to XP and still use it as my main computer. The challenge was to find PCI cards with that kind of versatility. I use an Ensoniq ES1370 for sound, it has good DOS and Windows 3 compatibility but with the Axiomtek board I might be able to use a true ISA card like an AWE32. I use SCSI hard drives with an Adaptec 19160 and an AGP nVidia TNT2 Ultra as graphic card. That’s the most advanced card I could find that still has Windows 3 drivers and it’s the one real bottleneck on the system.

  18. Michal Necasek says:

    Yes, finding hardware that supports both the old and the new is really challenging. I’ve done similar puzzling over portables, namely IBM ThinkPads. The systems that run DOS and Windows 3.1 well aren’t great for Windows XP, and the slightly newer systems that can take a fast enough CPU and a reasonable amount of RAM don’t support DOS/Windows 3.x anymore.

  19. Claude Herail says:

    If both ISA and AGP are a must, this company actually still makes computers that have both: http://www.duropc.com/catalogsearch/result/?q=AGP. I’m afraid that Pentium 4 boards are the upper limit for AGP. If only ISA is required, they have a lot more options: http://www.duropc.com/catalogsearch/result/?q=ISA. Unfortunately they don’t seem to sell individual motherboards.

  20. Michal Necasek says:

    A Core i7 with ISA sounds pretty interesting 🙂 I’m not sure I’d call it a “museum PC”, but interesting nevertheless.

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