> I'm looking for advice on upgrading a scientific instument computer
> (GC/MS). The instrument uses three ISA (AT) PC controller boards. The
> instrument PC boards use fixed IRQ's 5 and 9. I'd like to upgrade to a
> fast Pentium computer running WinXP. The candidate computer must have
> three ISA (AT) slots available and IRQ's 5 and 9 must be available for
> reservation. I don't think that IRQ 5 is a problem but I think IRQ 9
> might be a problem. It seems that in modern computers IRQ 9 is used
> for a Microsoft ACPI compliant system(Advanced Configuration and Power
> Interface).
>
not that modern computers I guess :-)
Historically there are different behaviors of ACPI in different ACPI-
aware operating systems and different ACPI-aware PC hardware.
What you describe could be true about ACPI in Windows 98 maybe, on pre-
APIC hardware. IMO, Windows XP behaves just fine (and so does Linux)
specifically on hardware that contains an IO APIC - that's all Intel
chipsets
from i845 and above, including the i852/855 mobile north bridge
combined with an ICH4-M or 6300ESB south bridge. The on-chip IO APIC
is a part of the south bridge, so I should've written ICH4(M) and
above :-)
With the IO APIC, I believe the IRQ9 has no special meaning, the other
interrupt sources are usually spread evenly among IRQ's 16-23. If
there is an APIC and yet IRQ9 is used by one (or more) PCI devices,
such as the USB ports, it should be possible to move them elsewhere by
reserving IRQ9 for "Legacy ISA" in the BIOS Setup. Modern Windows/
Linux do their APIC-based interrupt routing based on BIOS-provided
ACPI/MPS tables, that's why the BIOS reservation works.
I believe that any motherboard / PICMG CPU board with ISA capability
must have a menu in the BIOS, which allows you to give up individual
legacy IRQ numbers selectively to PCI/ISA PnP or reserve them for
legacy ISA (the truly dumb bus that has no IRQ auto-negotiation
capabilities). E.g., in the Award BIOSes that are present on most
Advantech industrial PC hardware, this menu is called "PCI/PnP
Configuration". I don't have a screenshot, but right now I've checked
on a live Advantech PCI-6187 that IRQ9 is eligible for this
reservation to legacy ISA, and I believe it would actually work.
Note that if you can find some ATX motherboards with ISA still on the
market, they'll be industrial models, which is not a problem, but
secondly they'll likely require a Socket 478 CPU - some P4 or P4/
Celeron. These CPU's have been off the biege-box market for maybe a
year. You'll be able to get them from some vendor of industrial PC
hardware, at a premium. Perhaps most importantly, they are power
hungry and tend to run rather hot, the higher-end models can present a
problem to your PC case's ventilation. They are enough to run Windows
XP, but the throughput of chipsets such as i845 or any other of the
i8xx family is nowadays nothing to write home about. All of this
applies to the aforementioned Nexcom ATX board and e.g. some Advantech
products, such as AIMB-740 or PCA-6186 / PCA-6187. Further, if you
take this route, note that there were two sorts of P4 CPUs in
Socket478 - and e.g. the i845 chipset doesn't support the newer-
generation P4 CPU's with Prescott core, though the socket is the same
(i865/875 does support Prescott). If you observe those caveats, you
should have a perfectly proven and stable system.
Next, the aforementioned Nexcom board is perhaps the only ATX
motherboard with 3 ISA slots for the P4 CPU (note that the chipset is
i845). If you want a better chipset or even better CPU, you'll need to
consider the PICMG1.0 form factor (CPU board + passive backplane, with
ISA in the picture). The PICMG backplanes don't fit into regular ATX
chassises, so you'd need a new chassis too (probably 19"/4U rackmount,
though smaller boxes are possible, too). As for chassises and
backplanes, I have lots of experience with Advantech stuff.
http://www.advantech.com/products/Mo...6OD&BU=NCG&PD=
As for PICMG1.0 CPU boards, let me mention the following models:
1) the Advantech PCA-6189 for the Pentium M / Dothan. The Dothan CPU
is a previous generation of mobile Intel CPU's (for notebooks) - it
has enough CPU horsepower to run Windows XP, it has more power per
clock cycle than the P4 (Netburst), so that although it runs at lower
nominal clock rates than the P4, it's not all that feeble. It does not
have a Netburst core, its direct ancestor is the Pentium III, and its
direct heir is perhaps the Core/Core2 CPU. Most importantly, it runs
quite cool - you won't have a problem with heat dissipation, which has
positive impact on overall reliability of the computer. Unfortunately,
as far as I know, it's off the biege-box shelves at the moment too, so
you'd have to buy it from Advantech or some other "embedded" vendor.
Not that much of a problem if you'd be buying PICMG hardware anyway.
http://www.advantech.com/products/Mo...6J7&BU=NCG&PD=
2) recently there have been several announcements of PICMG 1.0 CPU
cards for the Core2Duo CPU's in LGA775 socket. All of these are based
on the i945 chipset, which is the lowest stock chipset for the C2D -
there are no PICMG 1.0 CPU boards with the i965 or i3000 series. But
at least finally it's C2D, which is a current off-the-shelf CPU :-)
Among these boards, I have experience with the WSB-9454 by IEI. The
manual does list IRQ9 as eligible for ISA reservation, BTW.
http://www.iei.com.tw/en/product_IPC.asp?model=WSB-9454
Pentium 4 or Pentium D (any Netburst CPU) in LGA775 are IMO not worth
the bother anymore, though PICMG boards do exist for them. C2D eats
less and is more powerful.
If you decide to use some LGA775 CPU, consider also ordering a more
sturdy heatsink than what's "boxed" with Intel LGA775 CPU's.
Specifically, the heatsink body and fan are not a problem, but I have
objections against the plastic flippers that you ram into mounting
holes in the motherboard, and that are supposed to hold the heavy
heatsink. There are heatsinks with metal screws (M3 thread I believe),
supplied with a bottom-side mounting pad (with metal nuts molded in)
that gets stuck from the downside of the CPU board. Examples:
Spire quadroflow
http://www.spirecoolers.com/main/product_cpu.asp?p=14
Some CoolerMaster products
http://www.coolermaster.com/index.ph...st&p_class=114
If you happen to opt for any PICMG board with an Intel "mobile"
chipset, i.e. a chipset specifically designed for notebooks, be aware
that the stock/desktop Windows driver has an interesting feature,
where it falls back to the (internal) LVDS interface for direct LCD
attachment, if there's no VGA monitor attached at the time of boot -
and keeps the setting across reboots. If that's a problem, consider
using the Intel "XP embedded" driver. It works fine in classic desktop
XP. Obviously the desktop chipsets don't suffer from this "feature".
If you ever need to use an ISA board that uses memory-mapped IO, i.e.
needs a straight-through memory window, you may have a problem finding
such an available free window on modern ISA-capable CPU board. Maybe
this is due to the fact that i8xx chipsets and above don't have ISA in
the standard functionality, so that board vendors have to add external
PCI-to-ISA bridges (such as the ITE 8888) - another big chip on the
CPU board, that handles the ISA part of the PICMG 1.0 slot connector.
Or maybe it's just because there's a lot of memory-mapped stuff in a
modern PC, don't know exactly. I have to say that in all cases where a
customer had a problem to find a free ISA MMIO window, I was able to
find one - I used memory maps from Linux as a clue, and although these
are sometimes a bit mis-reported, I've always been able to start from
those and find a valid block of 2kB or 4kB of memory that wasn't
jammed by the CPU board.
Note that ISA MMIO hardware has always been rare - I remember some
voice-processing boards and X.25/sync serial network boards. If you
don't know what this is, it doesn't apply to you.
As for IRQ9 vs. ACPI: I've seen IRQ11 heavily abused on some APIC-less
ACPI-aware systems. IRQ9 also does appear in the Windows "resouce
lists" often multiple times, but I don't think it should be a problem
to reserve it in the BIOS, despite the fact that this is traditionally
"cascaded" from IRQ2. Perhaps this cascading is overridden by ACPI
+APIC, I don't know for sure...
If you're switching from DOS or DOS-based Windows to Windows XP, note
that any legacy software based on direct hardware access won't work
anymore. You'll need Windows NT/2000/XP drivers for your ISA hardware,
and you'll need application software that's written to use those
Windows drivers. In the absence of Windows drivers, you can work
around the problem using some general-purpose library like DLportIO,
but that won't allow you to use IRQ handling (no way to hook up a
handler from user space)...
> BTW, the computer also needs to communicate with other parts of the
> instrument system with serial ports COM1 and COM2, but I think that
> COM ports could be easily provided.
>
not on desktop boards anymore. Perfectly allright on any "industrial"
motheboard or PICMG CPU board. If one or both COM's are not on the
rear bracket, there are always headers inside on the CPU board, and an
additional COM bracket is a standard accessory, with cable pigtails
that match the onboard COM headers. Check the manual of your selected
hardware.
Frank Rysanek
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