Hi there,
Not sure if they'll have quite the information for which you're looking, but
for all my low level programming needs I always turn to
[OSDev](https://wiki.osdev.org/Expanded_Main_Page).
Hope this helps!
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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, February 3rd, 2022 at 8:46 AM, G.W. Haywood via Freedos-user
freedos-user@lists.sourceforge.net wrote:
> Hi there,
>
> Sorry to rake up an old thread, it's what I could find in the archives.
>
> If Sourceforge provides a better search tool than what I've seen I'd
>
> be very pleased to know about it. I found this using a Google clone.
>
> On 2018-06-21 Ralf Quint wrote:
>
>> ... I am currently away from my FreeDOS programming stuff, I could
>>
>> send you some diagnostic tool either tomorrow or over the weekend ...
>
> My application is a very old suite of business software which I wrote
>
> about 30 years ago and is still in very active use. It's a multi-user
>
> sales/purchases/stock control/ etc. accounting system. It runs under
>
> FreeDOS, MS-DOS and Linux. It can use multiple serial port cards for
>
> the user terminals. The largest DOS installation I've done was eleven
>
> terminals (+console), although most only use one or two. Changes in
>
> legislation in the UK mean that here and there an extra I/O port will
>
> be wanted for what HMRC calls the 'digital link' between the business
>
> software and the desktop stuff which interfaces with HMRC's computers.
>
> The multi-port cards I've used in the past have been ISA. I did have
>
> to modify some of them to share interrupts, but that's always worked
>
> OK. Of course these won't fit in most recent computers. Multi-port
>
> PCI cards I've seen handle interrupt and I/O addressing differently
>
> from the way the ISA cards did it. I/O addresses are no problem, any
>
> address is configurable in the software, but despite claims to be able
>
> to use IRQ3 and IRQ4 in the sales literature none of the PCI cards
>
> that I've tried so far appears to be able to use either. My software
>
> expects that only those will be used for serial comms (if you think
>
> that means the software is silly, I'd blushingly have to agree).
>
> At some point I'd like to modify the software to handle more recent
>
> hardware but it's a long time since I did all that and I've almost
>
> forgotten how it all hangs together. If for example there's a TSR or
>
> something which can say route IRQ19 to IRQ3 I think that would do for
>
> the forseeable future, but I don't even know yet if that makes sense.
>
> If you (or anyone else) can point me to comprehensive and reliable
>
> documentation and/or tools useful for the investigation and routing of
>
> interrupts for PCI expansion cards under DOS I'd be most grateful.
>
> ---------------------------------------------------------------
>
> 73,
>
> Ged.
>
> Freedos-user mailing list
>
> Freedos-user@lists.sourceforge.net
>
> https://lists.sourceforge.net/lists/listinfo/freedos-user
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