Reduction of the average access time with thin-film head arrays

The average access time, t
a
, of a moving head disc file can be drastically reduced by the application of multi-track Thin-Film Head Arrays. It is shown analytically that t
a
= t
s
+ 16/15(S
m
/a)
^1/2
, where t
s
is the settling time, S
m
, the maximum seek length and a, the constant acceleration and deceleration. When eight arrays each containing 25 thin-film heads are used to cover a 50 mm span of disc recording surface with a track density of about 40 track/mm, the average access time on the order of 2 to 6 m sec. can be achieved depending on the settling time, with present batch fabricated vertical inductive head design and constant acceleration and deceleration of 10,000 to 20,000 cm/sec
²
.