Computer Interfacing

Computer interfacing

(a) The write operation (b) The read operation

Figure

7.1

Action

of the

read/write head

in

writing

or

reading

data

in bit

cells

disk, they are rather small in size! During the read op-

eration, the head will, by induction, pick up a minute

voltage (V

R

in Figure 7.1) from one of these bit cells as it

passes over it.

Recording codes

There is a number of ways of storing binary digits in the

bit cells referred to. These are illustrated in Figure 7.2,

to which the following notes refer:

(a) return to zero (RZ): a logic 1 is represented by one

magnetic state for part of the cell, the rest being returned

to zero magnetisation