IBM 1130 User Manual page 469

Section
Subsections Page
60
10
I
10 01
Cylinder 0
This area contains certain key information that is
present on every disk cartridge. The exact contents
of this area differ, depending on whether the disk in
question is a systems disk (in which case
it
contains
the Monitor) or a non-systems disk; the area, how-
ever, is always present, and always occupies one
cylinder, Cylinder
o.