Check the date:
This classic article from Mario Wolczko first appeared on Usenet in 
1986. 
I don't think that they had the option to boot from cdrom.


On 4 May 01, at 21:23, Austad, Jay wrote:

> What version of unix was it?  If solaris, they could have just put in the
> cdrom and done "boot -s cdrom" or if linux just used Tom's root boot.  I
> assume other Unices also have some sort of boot from cdrom in single-user
> mode feature.
>