The above is from the FAQ, and the question exactly matches my problem but the answer has no relevance to me at all.Q: When I start my VM, I get an error stating that no boot medium was found. How do I solve this?
A: Please read more about Virtual Machines so you know what VirtualBox actually does. Basically it comes to that it 'simulates' a computer with hardware and everything. The Guest does not know about the Host or it's hardware. So you have to install a seperate Operating System in it before you can really use VirtualBox.
Also make sure that if you want to boot from a CD/DVD or ISO, that it actually is bootable.
My hardware is an AMD Athlon 5150 (64 bit) with 64GB of RAM, but its only peripherals are its VGA monitor, 2TB SATA hard drive, and a USB 2 controller, into which are plugged my keyboard, mouse, and the DVD-RW drive from which I need to boot. The drive has in it an original Windows 98 boot CD. Host operating system is Ubuntu 17.04 (64 bit).
VirtualBox allows me to create, and start, a virtual machine named "Windows 98", and VB's console window shows that the existence of the optical drive is recognized:
"IDE Secondary Master: [Optical Drive] Host Drive ASUS SDRW-08D2S-U (sr0)"
And still it refuses to boot Windows 98, but pretends that no CD is in the drive. How do I make it work?
(Yes, I did read the "minimum requirements" post, but I don't think I've gotten far enough that I could meaningfully comply.)