Disk Memory System
DISKETTE INFORMATION
Your disk system requires
5\4
inch. single-sided. single-density. soft-sectored diskettes.
These diskettes are constructed of a highly flexible plastic film. coated with a thin layer
of iron oxide which can be magnetized in very small areas without affecting
surrounding areas. The computer interprets these areas of magnetization as coded
information.
Note:
A diskette comes in a protective jacket inside a storage envelope. For best results.
keep the diskette in the storage envelope except while using. Never remove the diskette
from its protective jacket.
A single-sided diskette is divided into tracks which are 40 (on some diskettes only
35)
concentric circles. The tracks are numbered from 0 to 39. starting at the outside track.
Each track. in turn. is divided into nine sectors. Thus. there are 360 sectors. each of
which can contain up to
256
bytes of information. or 2048 bits. The sectors are
numbered 0 through
359.
starting with sector 0 of the first track and going to sector
359
on the last track. Each sector has additional space used only by the controller to
verify sector identification and data accuracy.
A double-sided diskette has 80 tracks. The tracks are numbered 0 to
39
on one side.
starting with the outer track. and 40 to 79 on the other side. starting with the inner
track. Each track is divided into nine sectors giving a double-sided diskette 720 sectors.
Each sector can contain up to
256
bytes of information. or 2048 bits. The sectors are
numbered 0 to 7 19. starting with sector 0 on the first track of the lower side. and sector
359
on the last track of the lower side. Sector 360 is on the last track of the upper side
and sector 7 1 9 is on the first track of the upper side. Each sector has additional space
used only by the controller to verify sector identification and data accuracy.
The disk controller uses sectors 0 and 1 of the first track to form an index of file
locations. If those sectors become damaged and unreadable. the computer cannot locate
any files on the diskette. and the contents of the entire diskette will be unusable.
To use your disk drive system. insert the proper diskette. and use TI BASIC or a
Command Module designed to operate with the disk system. The work of keeping track
of your files and reading from or writing on the proper place on the disk is taken care of
by the system.
Diskettes can be named for reference purposes. The name of a diskette can be up to 10
characters long and may use any characters except the period and the space character.
Valid names for diskettes include:
DISK21
TIR�DATA
MYDISK
GEORGE
The following are not valid diskette names.
3.1416
MY DISK
PR�DATA
BU03/24/BO
THISNAMEISTOOLONG
5
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