I have installed MS-DOS 6.22 (released in 1994) on Virtual Box, and I want to know if Virtual Box is emulating an ISA bus or a PCI bus. The settings for my virtual machine don't show any information about the bus.

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    All PCs have what looks to software to be an ISA bus. Modern PCs without a physical ISA bus use the LPC bus instead to connect ISA compatible devices like serial ports and a PS/2 keyboard/mouse controller (usually provided by a single Super I/O chip). Software running on a real PC can't really tell the difference between a device on an ISA bus from the same device on a LPC bus so it doesn't really matter whether a virtual machine emulating a PC emulates an ISA or LPC bus. Both look the same to software, so for all intents and purposes all VMs have an ISA bus.
    – user722
    Commented Jun 7, 2017 at 21:26
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    And now even the LPC bus is being obsoleted, by eSPI... Commented Jun 7, 2017 at 22:03
  • @Ross Ridge that sounds like an answer, and a correct one at that. Commented Aug 18, 2017 at 21:26

1 Answer 1


If you went with VirtualBox's default settings for an MS-DOS system, you've got both: an Intel 440FX northbridge providing a PCI bus, and an Intel PIIX3 southbridge connected to that bus, providing an ISA bus. The virtual video card (generic VESA-compatible) and PCnet-FAST III network card will be attached to the PCI bus. The sound card (a virtualized SoundBlaster 16) will be attached to the ISA bus. The hard drive and CD-ROM will be on a PIIX4 connected to the PCI bus.

(Source: attaching a SysRescueCD to an MS-DOS VM and seeing what the diagnostics had to say.)


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