Xerox 7240 Reference Manual page 13

20 Surfaces,
20 Heads
Surface 0
Surface 18
Surface 19
Sector Mark tt
A
Gap
s Header Preamble
c Header Data
o
Header Parity
E
Header Postamble
F
Post Header Gap
512 Bits
136 Bits
64
Bits
16 Bits
8 Bits
512 Bits
I
Rotation
6 Sectors
/
~ectorO
!
Sector
5
203 Cylinders
Cylinder 202
Cylinder 201
_,_-=------~r---
Cy Ii nder
1
Cylinder
0
=:/,~E;zrz:z::=zz:=zz=2]Z::S:::1/~':,~>~~
Index Mark tt
/ Sector Mark
tt
Typical
Sector
G
Data Preamble
H
Data
1
Data Parity
J
Data Postamble
K
Post Data Gap
136 Bits
8192 Bits
16 Bits
8
Bi ts
680 Bits
Typical
Cylinder
I
tData is not recorded on top or bottom surface. ttSector marks and index mark are on index disk (not shown).
Figure 1. Disk Pack Organization
Disk Pack Organization 5