Gestetner B147, Service Manual

Page: 975 / 1081

SM 17 B692/B694
B
692
/B
69
4
Da
ta
Over
write
Security Uni
t
A copy or print job always starts writing data to disk, starting with the clusters at the
outer edge [A] and progressing toward the center.
The overwrite, on the other hand, always begins at the center cluster [B] and
progresses toward the edge.
Taking the first square as cluster 1 on the outermost track:
•
A job starts writing from 1, 2, 3, and continues toward 32.
•
At the end of the job , the Security module overwrite erase proceeds from the
opposite direction, starting from 32, 31, 30 on the innermost track and continues
to 1.
NOTE: Each number in the illustration represents 1 cluster, the smallest unit the
operating system uses to handle data on the HDD.
If a copy or print job starts during data overwrite, the job has priority and the
overwriting stops, and the copy or print job begins.
10
11
12
13
14
15
16
6
5
4
3
2
1
23
24
25
26
27
28
22
21
20
19
18
17
.
.
.
.
32
31
30
29
7
9
8
B692D902A.WMF
[A]
[B]
HDD Data
Overwrite