> > When I did my Linux parallel port driver rewrite some years ago, the
> Can't even remember where I got this story from or if it's a urban legend
> of the computer bussines, so just take it for your personal amusement,
HCF is urban legend as far as production chips go
I remember a Byte article from the late 1970's about undocumented 6502
instructions. One of them put the CPU in a state where it strobed and
continuously incremented the address bus until the chip was reset, and
did nothing else that the author could determine. He nicknamed that
instruction HCF and hypothesized that it was for automated testing (to
verify that the address bus could generate all possible addresses).
-- Robert Krawitz <rlk@tiac.net> http://www.tiac.net/users/rlk/Member of the League for Programming Freedom -- mail lpf@uunet.uu.net Tall Clubs International -- tci-request@aptinc.com or 1-800-521-2512