Diskette Description - IBM 3274 51C Maintenance Information

E.1.1.1 Diskette Description
The IBM 31 SO Diskette, shown in Figure E-2, is a thin,
flexible disk, permanently protected in a jacket. Informa-
tion is stored magnetically on the diskette surface, which is
covered with magnetic recording material. The diskette is
free to turn inside the jacket. As the diskette turns, the
inner surface of the jacket cleans the diskette.
Access Hole for
Index Sensing
Access Hole for
I
Rotating the Diskette
___ - .. /lc.cess.I-l'1le fnr
1--=-1
R.ad/Wdtc Head Contact
IBM
Dlske
Diskette
The diskette jacket has three holes. The first hole per-
mits the diskette drive to turn the diskette, the second hole
permits the read/write head to make contact with the disk-
ette, and the third hole permits the phototransistor light to
go through the index hole to sense the type of diskette.
For storage, the diskette, which is permanently protected
in a thin jacket, can be placed in an envelope. Data can be
read from or written on only one side of the diskette.
Information is written on the diskette in tracks. A track
is a circular path on the diskette surface. Information is
magnetically written to or read from a track by a read/
write head as the diskette turns. See Figure E-2 ..
/---~~-~~~~-------------------------:- ~~~:~
oo}
Cylinder 0
,/ : Side 0
' , L - -
Track 00
Side 1 }
Track 76 Cylinder 76
Side 0
Track 76
Figure E-2. 31 SD Diskette
E4