As he did some years ago, Gates pinned the blame on the IBM engineers responsible for the IBM PC keyboard at the time.
Grinning, he answered: "The IBM PC hardware keyboard only had one way that it could get a guaranteed interrupt generated. So, clearly the people involved, they should have put another key on it to make that work. A lot of machines these days do have that as a more obvious function."
Rubenstein pressed Gates further, asking whether he regretted doing it that way. Gates sidesteps the question but admits he might do things differently now.
"Well, I'm not sure you can go back in life and change small things in your life without putting other things at risk. Sure, if I can make one small edit, I'd make that a single-key operation."
In 2013 Gates said it was "mistake" requiring the three keys before logging in to Windows, and also blamed IBM engineers who "didn't wanna give us our single button".
The three-key function was created by IBM engineer David Bradley who intended for it to be shortcut to rebooting an IBM PC.
On a panel in 2011 with Gates, Bradley said, "I have to share the credit. I may have invented it, but Bill made it famous", by using it for the Windows NT logon.
As Ars Technicanoted at the time, the function was initially a BIOS feature, but Microsoft made it software feature in Windows 3.0's Enhanced Mode.
Later, Microsoft hoped to sell Windows NT to the US government, which required a Secure Attention Key (SAK) that only the operating system could respond to. This stipulation was to prevent malware from spoofing a login prompt. Ctrl-Alt-Del became Windows' SAK.