<s>
AMSDOS	B-Operating_System
is	O
a	O
disk	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
for	O
the	O
8-bit	O
Amstrad	B-Device
CPC	I-Device
Computer	O
(	O
and	O
various	O
clones	O
)	O
.	O
</s>
<s>
AMSDOS	B-Operating_System
first	O
appeared	O
in	O
1984	O
on	O
the	O
CPC	O
464	O
,	O
with	O
added	O
3	B-Device
inch	I-Device
disk	I-Device
drive	O
,	O
and	O
then	O
on	O
the	O
CPC	O
664	O
and	O
CPC	O
6128	O
.	O
</s>
<s>
Relatively	O
fast	O
and	O
efficient	O
for	O
its	O
time	O
,	O
AMSDOS	B-Operating_System
was	O
quicker	O
and	O
more	O
effective	O
than	O
most	O
of	O
its	O
contemporaries	O
.	O
</s>
<s>
AMSDOS	B-Operating_System
was	O
provided	O
built	O
into	O
ROM	O
(	O
either	O
supplied	O
with	O
the	O
external	O
disk	O
drive	O
or	O
in	O
the	O
machine	O
ROM	O
,	O
depending	O
on	O
model	O
)	O
and	O
was	O
accessible	O
through	O
the	O
built-in	O
Locomotive	B-Language
BASIC	I-Language
as	O
well	O
as	O
through	O
firmware	B-Application
routines	O
.	O
</s>
<s>
Its	O
main	O
function	O
was	O
to	O
map	O
the	O
cassette	B-Device
access	O
routines	O
(	O
which	O
were	O
built	O
into	O
every	O
CPC	O
model	O
)	O
through	O
to	O
a	O
disk	O
drive	O
.	O
</s>
<s>
This	O
enabled	O
the	O
majority	O
of	O
cassette-based	O
programs	O
to	O
work	O
with	O
a	O
disk	O
drive	O
with	O
no	O
modification	O
.	O
</s>
<s>
AMSDOS	B-Operating_System
was	O
able	O
to	O
support	O
up	O
to	O
two	O
connected	O
disk	O
drives	O
.	O
</s>
<s>
AMDOS	O
extends	O
the	O
AMSTRAD	O
BASIC	O
by	O
the	O
addition	O
of	O
a	O
number	O
of	O
external	O
commands	B-Application
which	O
are	O
identified	O
by	O
a	O
preceding	O
¦	O
(	O
bar	O
)	O
symbol	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
list	O
of	O
external	O
commands	B-Application
supported	O
by	O
AMSDOS	B-Operating_System
.	O
</s>
<s>
Other	O
disk	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
for	O
the	O
Amstrad	O
range	O
included	O
CP/M	B-Application
(	O
which	O
was	O
also	O
bundled	O
with	O
an	O
external	O
disk	O
drive	O
,	O
or	O
built-in	O
on	O
ROM	O
depending	O
on	O
model	O
)	O
,	O
RAMDOS	O
,	O
which	O
allowed	O
the	O
full	O
(	O
800K	O
)	O
capacity	O
of	O
single-density	O
3	O
½	O
"	O
disks	O
to	O
be	O
used	O
providing	O
a	O
suitable	O
drive	O
was	O
connected	O
and	O
SymbOS	O
.	O
</s>
