SECTION 1
GENERAL DESCRIPTION
INTROOU CTION
i nt e l l i g e n t
t er m i n a l con t r o l l e r s , m i c r o -
computers, word processing systems, data
com-
munication systems, error logging, program
loading, and point-of-sale terminal s.
T his document pr ovides required in f or m a t i on
in order to evaluate or incorporate Tandon's
disk drive
into a
system.
T ando n C o r poration's M o del N u m b e r s
TM848-1E and TM848-2E, eight-inch flexible
drives are full-feature, microprocessor-
c ontrolled d r i v es. T he y m a y b e i n s t a l le d i n
o ne-half t h e s p ace norm a ll y r e q u i re d fo r a n
eight-inch drive.
They are compact data stor-
age devices that use an IBM - f or m a t t ed, indus-
t ry standard, eight-inch di skette. Both dr i v e s
are 48 tracks per
inch recording devices.
The Model TM848 series of
drives are capable
of r e a d in g
a n d w ri t i n g i n si n g l e - density
format on a diskette, using a proprietary
r ead/writ e h e a d p a t e n t e d b y Tan d o n . I n
addition, bot h d r i v e s h a v e a d o u bl e d ensity
capability w h en M o d i f ied F r equency Modula-
tion (MFM) or other appropriate recording
techniques are used. The encoding and decod-
ing of the data is done by the user's controller.
The Model T M 8 4 8-1E d r i v e u ses one side of
t he d i s k e tt e f o r d a t a s t o r a ge . T h e M o d e l
TM848-2E drive doubles data storage capabili-
ties by using both sides of the diskette.
1 .1 SCOPE OF THE DOCU M E N T
1.3 MA JOR FEATURES
M ICROP R O C E S S O R CO N T R O L
T he TM848-1E and T M 8 4 8-2E dr i ves featur e
an onboard mi croprocessor. This mi croproces-
sor provides six major features:
1. B u f f e red seek capabilit i es..
2 . I m p r oved h e a d p o s i t i o n in g a c c u r a cy
with reduced hysteresis.
3 . W r i t e c u r r e n t s w i t c h i n g f o r o p t i m a l
d ata recording qualit y .
4. T r u e Ready signal.
5. I n t e r nal diagnostics (strappable).
6. Power On Self- Tests.
WRITE PROTECT
When a w r i t e p r o t e cted d i sk ett e i s i n s e r t ed
i nto t h e dr i v e , t h e w r i t e e l e c t r o n ic s a r e
disabled.
T his document c ont a in s a d e scription o f t h e
major features, physical and fu n ct i onal speci-
fications, mountin g an d p o wer r e q u i r ements,
the int er f ace, and ty p i cal t i m i n g c h a r acteris-
tics of the TM848-1E and TM848-2E drives.
DAISY CHAIN CAPABILITY
1.2 P U RPOSE OF THE DRIVE
The drive provides the address selection and
gating functions necessary to daisy chain a
maximum o f f o u r u n i t s a t t h e u s e r's opti on.
T he last dr iv e on t h e d a isy chain t e r m i n a t e s
the i n t e r f ace. Th e t e r m i n a t i on s ar e a c c om-
p lished by a resistor array pl u gged into a DI P
socket.
T he T M 8 4 8 -1 E a n d TM 8 4 8 -2 E d r i v e s a r e
rotating d is k m e m o r ies designed for r a n d om
access data entry, storage, and retrieval
a pplicat i o ns . T y p i c a l a p p l i c a t i on s i n c l u d e
1-1
