My trusty 'ol ASUS T2P4 rev 3.1 supports CDROM boot.
And a quick search suggests it was available from launch and it was released in late 1996.
I dont think it was a common feature tho as most OS installs didn't support it until a few years later.

February 28, 1989 😀

https://en.wikipedia.org/wiki/El_Torito ... _standard)

El Torito is an extension to the ISO 9660 CD-ROM specification. It is designed to allow a computer to boot from a CD-ROM. It was announced in November 1994 and first issued in January 1995 as a joint proposal by IBM and BIOS manufacturer Phoenix Technologies. According to legend, the El Torito CD/DVD extension to ISO 9660 gained its name because its design originated in an El Torito restaurant in Irvine, California

Here's the original standard:
https://pdos.csail.mit.edu/6.828/2014/reading … /boot-cdrom.pdf

If your BIOS does not support the boot standard and you have an IDE CD-ROM drive, a boot manager like PLoP should let you boot from a CD if you can get it on a working boot device.
https://www.plop.at/en/bootmgr-new.html

The usual progression of these things is that:
- The spec emerges
- Things start supporting the spec (BIOS)
- Software starts to use the spec (Windows install CD, etc.)
- The crippling bugs and limitations get fixed

IIRC, I was recently able to accidentally boot from a CD with a floppy emulation image on a Super Socket 7 board. I was also NOT able to get an Adaptec AHA-2940 to boot from a disc in a SCSI CD-ROM, despite it detecting that it was authored as bootable. (I am not sure what media type its image specified -- I think it was a Linux disc, so probably No Emulation. Could also have been BeOS R5 Pro, and I'm not sure if that's a floppy image or NE.)

On a Pentium II, things seem to have been pretty much sorted out.

I'm familiar with the floppy emulation, but there's been other types of bootable CD/DVD's since than, yes?

What other bootable CD-Rom formats came out since then?

No need to install DOS first if the system can't boot directly to CD.

Win9x came with an install floppy boot disk. You boot to the floppy and then run setup from the CD.
https://www.retrocomputing.co.uk/p/windows-98 … stallation.html

douglar wrote on 2020-01-31, 20:35:

I'm familiar with the floppy emulation, but there's been other types of bootable CD/DVD's since than, yes?

It's just one of the options when you author the disc. For e.g., you can emulate a floppy, a "hard disk", or no emulation. AFAIK, floppy emulation and no emulation are the most common.

I made a CD with DOS 5, DOS 6.22, Win 3.0, 3.1, WFW 3.11, Win95, Win95C, Win98, Win98SE, and WinME. It has (among a couple others) a Win95C boot floppy image on it, and the rawrite tool to copy it to a floppy. But that same image is also bootable from the disc itself. I just used that last weekend to boot my Pentium 166 from CD and it works really well -- except it does take over the A: drive, so if you need to put in a floppy during Windows setup (upgrade check for e.g.), then you have to use B: to access it.