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We have inherited a legacy application which runs under DOS 6.2 and the Phar-Lap DOS extender (if anyone is old enough to remember that). It also uses up to 6 serial ports (16550) which are expected to exist at fixed port addresses & IRQs. There are still many of these systems in the field but the PCs are starting to fail and finding compatible motherboards is impossible due to the hard-coded IRQs used.

(The software installs interrupt handlers for the COM ports with COM3 to COM6 expected to use port/IRQ combinations of 3E8/10, 280/11, 2A0/12 & 3A8/15. With modern motherboards, this is a problem).

Does anyone know of any virtualization technology which allows you run-up a DOS guest on a host with 6 COM ports whose physical resources are mapped to the guest as above? The display requirement is VGA 640X480 and there is no network requirement.

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Qemu (and therefore KVM) lets you define arbitrary serial ports, but it's limited to 4 ports, and doesn't let you specify the interrupts/IO ports. For that you'd have to get to the source code.

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And the same is true for VM Workstation I believe. – MikeJ-UK Jan 28 '10 at 16:12
except for the part where the source code is actually meant to be modified to fit your purposes. – Javier Jan 29 '10 at 4:22

Virtualbox allows up to 2 serial ports with irq and i/o port configurations.

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A step in the right direction. I will try this despite the limitation of two ports. – MikeJ-UK Jan 28 '10 at 16:15

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