<s>
The	O
ZX	B-Device
Microdrive	I-Device
is	O
a	O
magnetic-tape	B-Architecture
data	I-Architecture
storage	I-Architecture
system	O
launched	O
in	O
July	O
1983	O
by	O
Sinclair	O
Research	O
for	O
its	O
ZX	B-Operating_System
Spectrum	I-Operating_System
home	O
computer	O
.	O
</s>
<s>
It	O
was	O
proposed	O
as	O
a	O
faster-loading	O
alternative	O
to	O
the	O
cassette	B-Device
and	O
cheaper	O
than	O
a	O
floppy	B-Device
disk	I-Device
,	O
but	O
it	O
suffered	O
from	O
poor	O
reliability	O
and	O
lower	O
speed	O
.	O
</s>
<s>
The	O
Microdrive	O
technology	O
was	O
later	O
also	O
used	O
in	O
the	O
Sinclair	B-Device
QL	I-Device
and	O
ICL	B-Device
One	I-Device
Per	I-Device
Desk	I-Device
personal	B-Device
computers	I-Device
.	O
</s>
<s>
Grillet	O
proposed	O
"	O
a	O
version	O
of	O
the	O
Learjet	O
Stereo	O
8	O
system	O
,	O
modified	O
to	O
allow	O
two	O
64k	O
core	O
images	O
per	O
track	O
for	O
roll-out	O
roll-in	O
swapping	O
using	O
the	O
KUTS	B-Device
protocol	O
"	O
.	O
</s>
<s>
Development	O
of	O
the	O
ZX	B-Device
Microdrive	I-Device
hardware	O
by	O
Sinclair	O
engineers	O
Jim	O
Westwood	O
,	O
David	O
Southward	O
and	O
Ben	O
Cheese	O
started	O
in	O
1982	O
.	O
</s>
<s>
Connecting	O
a	O
ZX	B-Device
Microdrive	I-Device
to	O
a	O
ZX	B-Operating_System
Spectrum	I-Operating_System
required	O
the	O
ZX	B-Device
Interface	I-Device
1	I-Device
unit	O
,	O
costing	O
£49.95	O
,	O
although	O
this	O
could	O
be	O
bought	O
packaged	O
with	O
a	O
Microdrive	O
for	O
£79.95	O
.	O
</s>
<s>
Later	O
,	O
in	O
March	O
1985	O
,	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
Expansion	O
System	O
was	O
launched	O
for	O
£99.95	O
.	O
</s>
<s>
This	O
consisted	O
of	O
Interface	B-Device
1	I-Device
,	O
a	O
Microdrive	O
,	O
a	O
blank	O
cartridge	O
and	O
several	O
cartridges	O
containing	O
Tasword	B-Protocol
Two	I-Protocol
(	O
a	O
word	B-General_Concept
processor	I-General_Concept
)	O
,	O
Masterfile	O
(	O
a	O
database	O
)	O
,	O
Quicksilva	O
's	O
Games	O
Designer	O
and	O
Ant	B-Application
Attack	I-Application
games	O
,	O
and	O
an	O
introductory	O
cartridge	O
.	O
</s>
<s>
A	O
total	O
of	O
eight	O
ZX	B-Device
Microdrive	I-Device
units	O
could	O
be	O
connected	O
to	O
the	O
Interface1	O
by	O
daisy	B-Application
chaining	I-Application
one	O
drive	O
to	O
the	O
next	O
via	O
an	O
electrical	O
connector	O
block	O
.	O
</s>
<s>
In	O
addition	O
to	O
the	O
QL	O
versions	O
,	O
dual	O
internal	O
Microdrives	O
were	O
included	O
in	O
the	O
related	O
ICL	B-Device
One	I-Device
Per	I-Device
Desk	I-Device
system	O
(	O
also	O
badged	O
as	O
the	O
Merlin	B-Device
Tonto	I-Device
and	O
Telecom	O
Australia	O
Computerphone	B-Device
)	O
.	O
</s>
