All I want to do is to find a copy or installation of the most recent (1990's) version of MS-DOS. I will then install it onto the USB I have ...Creating a DOS-bootable USB drive in Rufus is simple. First, connect your USB drive to
clicker counter the computer and select it in the “Device” dropdown menu.The "Create Bootable USB Drive" dialog will popup. Click Down-Arrow button, and select "More selection..." from the popup menu. The "Select source for creating bootable USB drive" dialog box shows. Select the option "Create MS-DOS bootable USB drive" and click "OK" button to close the dialog box.Once you have created your bootable DOS USB key, you can insert it into your PC and turn on your computer. Go into the BIOS (typically F2/Del/ESC) and select the USB drive as the first boot device. On newer systems, you might have to enable CSM / legacy boot mode.