From VI-Toolkit

When creating a virtual machine with MS DOS (or PC Dos) then you'll notice that there are a few issues.

The first major issue being that the VM will run one of your cores with a high CPU. The reason being that MS DOS did not idle your CPU when it wasn't doing nothing, so instead of having a VM that uses no CPU when not doing anything you have that 1 core going nuts.

The classical way to resolve that is by installing DosIdle.

As it doesn't appear to be available much, here's a copy.

Dos Drivers download

Other interesting notes for DOS users of VMware virtual machines:

You also might want to check out Zamba's page here:

and Ken Kato's pages here: