FreeDos guest runs very slow

[jus459]

Hi all,

I'm trying to run FreeDos 1.2 in vb but it runs very slow. As a test, I play Doom 1.9, but it's slow to the point that it's unbearable.

Host Specs:
Windows 10 64-bit
Intel i5-6400 2.41GHz
8 GB ram

Guest settings:
FreeDos 1.2
1 Core at 70%
128 MB ram

I attached the log, from start up of the vm to shutdown.

If you need any other info, please ask. Thanks!

[mpack]

128MB RAM for a DOS guest? That seems pointless, since most DOS apps can't address beyond 1MB, and DOS is not a multitasking OS. Even using expanded/extended memory a DOS app of the day couldn't expect more than about 16MB on a really top end PC.

DOS is not a supported guest OS, meaning that the only graphics available to a FreeDOS guest is basic VESA using an emulated chipset, so yes it will be slow. You'd have to select the lowest resolution available if you want a higher frame rate.

You might want to try enabling VT-x in your hosts BIOS - and then in the VM. That might squeeze out a few extra cycles.

[michaln]

Yes, the DOS version of DOOM is slow in VirtualBox. But that has nothing to do with FreeDOS.

[michaln]

DOS is not a supported guest OS, meaning that the only graphics available to a FreeDOS guest is basic VESA using an emulated chipset, so yes it will be slow. You'd have to select the lowest resolution available if you want a higher frame rate.

That's actually backwards. VESA graphics is not slow in VirtualBox, it is in fact quite fast. Try any version of Windows XP and later without Guest Additions for example, that's VBE. I don't think it's slow, we never had any complaints that it's slow.

The problem with DOOM 1.9 is that it's not using VBE but rather VGA, and specifically Mode X which causes lots of VM exits. It really is slow.