<s>
The	O
Adventure	B-Application
Game	I-Application
Interpreter	I-Application
(	O
AGI	O
)	O
is	O
a	O
game	O
engine	O
developed	O
by	O
Sierra	O
On-Line	O
.	O
</s>
<s>
The	O
company	O
originally	O
developed	O
the	O
engine	O
for	O
King	B-Device
's	I-Device
Quest	I-Device
(	O
1984	O
)	O
,	O
an	O
adventure	O
game	O
which	O
Sierra	O
and	O
IBM	O
wished	O
to	O
market	O
in	O
order	O
to	O
attract	O
consumers	O
to	O
IBM	O
's	O
lower-cost	O
home	O
computer	O
,	O
the	O
IBM	B-Device
PCjr	I-Device
.	O
</s>
<s>
The	O
player	O
controls	O
the	O
game	O
with	O
a	O
keyboard	B-Device
and	O
,	O
optionally	O
,	O
a	O
joystick	B-Device
.	O
</s>
<s>
After	O
the	O
launch	O
of	O
King	B-Device
's	I-Device
Quest	I-Device
,	O
Sierra	O
continued	O
to	O
develop	O
and	O
improve	O
the	O
Adventure	B-Application
Game	I-Application
Interpreter	I-Application
.	O
</s>
<s>
In	O
late	O
1982	O
,	O
IBM	O
began	O
work	O
on	O
the	O
PCjr	B-Device
,	O
a	O
lower-priced	O
variant	O
of	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
with	O
improved	O
graphics	O
and	O
sound	O
.	O
</s>
<s>
The	O
PCjr	B-Device
's	O
Video	O
Gate	O
Array	O
video	B-Device
adapter	I-Device
could	O
display	O
up	O
to	O
16	O
colors	O
at	O
a	O
time	O
—	O
a	O
major	O
improvement	O
over	O
the	O
Color	B-Device
Graphics	I-Device
Adapter	I-Device
's	O
four-color	O
limit	O
.	O
</s>
<s>
The	O
new	O
sound	O
chip	O
,	O
too	O
,	O
could	O
output	O
a	O
wider	O
range	O
of	O
tones	O
than	O
the	O
PC	B-Device
speaker	I-Device
.	O
</s>
<s>
They	O
discussed	O
some	O
requirements	O
for	O
the	O
game	O
,	O
and	O
IBM	O
supplied	O
Sierra	O
with	O
a	O
PCjr	B-Device
prototype	O
.	O
</s>
<s>
A	O
team	O
of	O
six	O
designers	O
and	O
developers	O
,	O
led	O
by	O
designer	O
Roberta	O
Williams	O
,	O
worked	O
on	O
the	O
game	O
that	O
was	O
eventually	O
titled	O
King	B-Device
's	I-Device
Quest	I-Device
.	O
</s>
<s>
An	O
Apple	B-Device
II	I-Device
version	O
credits	O
Arthur	O
Abraham	O
)	O
.	O
</s>
<s>
IBM	O
premiered	O
the	O
PCjr	B-Device
in	O
1984	O
;	O
it	O
did	O
not	O
sell	O
well	O
and	O
,	O
therefore	O
,	O
neither	O
did	O
King	B-Device
's	I-Device
Quest	I-Device
.	O
</s>
<s>
However	O
,	O
later	O
that	O
year	O
Tandy	O
Corporation	O
released	O
the	O
Tandy	O
1000	O
,	O
an	O
IBM	B-Device
PC	I-Device
compatible	O
that	O
succeeded	O
where	O
the	O
PCjr	B-Device
failed	O
.	O
</s>
<s>
King	B-Device
's	I-Device
Quest	I-Device
caused	O
a	O
sensation	O
in	O
the	O
burgeoning	O
market	O
of	O
PC-compatible	O
computers	O
,	O
and	O
Sierra	O
sold	O
more	O
than	O
half	O
a	O
million	O
copies	O
.	O
</s>
<s>
They	O
ported	O
it	O
to	O
other	O
computing	B-Device
platforms	I-Device
,	O
including	O
the	O
Apple	B-Device
II	I-Device
,	O
Apple	B-Device
IIGS	I-Device
,	O
Macintosh	B-Device
,	O
Amiga	B-Device
,	O
and	O
Atari	B-Device
ST	I-Device
,	O
but	O
the	O
PC	O
remained	O
the	O
primary	O
platform	O
for	O
their	O
games	O
.	O
</s>
<s>
In	O
1988	O
,	O
with	O
the	O
release	O
of	O
King	B-Device
's	I-Device
Quest	I-Device
IV	I-Device
:	I-Device
The	I-Device
Perils	I-Device
of	I-Device
Rosella	I-Device
,	O
Sierra	O
debuted	O
a	O
more	O
sophisticated	O
game	O
engine	O
:	O
Sierra	O
's	O
Creative	O
Interpreter	O
,	O
or	O
SCI	O
.	O
</s>
<s>
The	O
following	O
year	O
,	O
Sierra	O
published	O
its	O
final	O
AGI-based	O
title	O
,	O
Manhunter	B-Application
2	I-Application
:	I-Application
San	I-Application
Francisco	I-Application
,	O
then	O
focused	O
exclusively	O
on	O
SCI	O
for	O
new	O
adventure	O
game	O
development	O
.	O
</s>
<s>
Among	O
SCI	O
's	O
enhancements	O
were	O
a	O
more	O
versatile	O
scripting	O
system	O
,	O
an	O
object-oriented	B-Language
programming	I-Language
model	O
,	O
higher-resolution	O
graphics	O
(	O
320×200	O
rather	O
than	O
160×200	O
)	O
,	O
a	O
point-and-click	O
interface	O
,	O
and	O
support	O
for	O
additional	O
sound	B-Device
card	I-Device
hardware	O
.	O
</s>
<s>
The	O
technical	O
complexity	O
of	O
King	B-Device
's	I-Device
Quest	I-Device
made	O
it	O
a	O
burden	O
to	O
write	O
in	O
assembly	B-Language
language	I-Language
,	O
so	O
the	O
programmers	O
created	O
a	O
game	O
engine	O
to	O
simplify	O
development	O
.	O
</s>
<s>
The	O
engine	O
comprised	O
a	O
bespoke	O
programming	O
language	O
called	O
the	O
Game	O
Adaptation	O
Language	O
,	O
a	O
compiler	B-Language
,	O
and	O
a	O
bytecode	O
interpreter	O
(	O
the	O
Adventure	B-Application
Game	I-Application
Interpreter	I-Application
)	O
.	O
</s>
<s>
The	O
Game	O
Adaptation	O
Language	O
was	O
a	O
high-level	B-Language
programming	I-Language
language	I-Language
that	O
resembled	O
C	B-Language
.	O
This	O
was	O
compiled	B-Language
into	O
bytecode	O
,	O
which	O
was	O
executed	O
by	O
the	O
interpreter	O
.	O
</s>
<s>
Like	O
Sierra	O
's	O
earlier	O
adventure	O
titles	O
,	O
such	O
as	O
Wizard	B-Application
and	I-Application
the	I-Application
Princess	I-Application
(	O
1980	O
)	O
,	O
AGI	O
games	O
used	O
vector	O
graphics	O
.	O
</s>
<s>
The	O
PCjr	B-Device
accepted	O
floppy	B-Device
disks	I-Device
with	O
a	O
capacity	O
of	O
360	O
kilobytes	O
,	O
and	O
raster	B-Algorithm
graphics	I-Algorithm
would	O
have	O
consumed	O
an	O
excessive	O
amount	O
of	O
disk	O
space	O
.	O
</s>
<s>
Instead	O
,	O
King	B-Device
's	I-Device
Quest	I-Device
drew	O
polygons	B-General_Concept
on	O
the	O
screen	O
,	O
and	O
then	O
colored	O
them	O
.	O
</s>
<s>
Beginning	O
with	O
AGI	O
version	O
2	O
,	O
the	O
game	O
engine	O
drew	O
graphics	O
in	O
an	O
off-screen	O
data	B-General_Concept
buffer	I-General_Concept
,	O
then	O
blitted	B-Algorithm
them	O
into	O
video	O
memory	O
.	O
</s>
<s>
AGI	O
was	O
principally	O
developed	O
for	O
16-bit	B-Device
computer	I-Device
architectures	O
,	O
which	O
were	O
the	O
state	O
of	O
the	O
art	O
in	O
home	O
computers	O
at	O
the	O
time	O
.	O
</s>
<s>
These	O
included	O
the	O
IBM	B-Device
PC	I-Device
compatible	O
,	O
the	O
Atari	B-Device
ST	I-Device
,	O
Commodore	O
's	O
Amiga	B-Device
series	O
,	O
and	O
Apple	O
's	O
Macintosh	B-Device
computers	O
.	O
</s>
<s>
In	O
addition	O
,	O
Sierra	O
ported	O
AGI	O
to	O
three	O
8-bit	O
computer	O
models	O
:	O
the	O
TRS-80	B-Device
Color	I-Device
Computer	I-Device
,	O
the	O
Apple	B-Device
IIe	I-Device
,	O
and	O
the	O
Apple	O
IIc	O
.	O
</s>
<s>
Game	O
PC	O
Apple	B-Device
II	I-Device
Atari	B-Device
ST	I-Device
Amiga	B-Device
Apple	B-Device
II	I-Device
Mac	B-Device
TRS-80	B-Device
CoCo	I-Device
King	B-Device
's	I-Device
Quest	I-Device
King	B-Device
's	I-Device
Quest	I-Device
II	I-Device
:	I-Device
Romancing	I-Device
the	I-Device
Throne	I-Device
The	B-Device
Black	I-Device
Cauldron	I-Device
Donald	B-Device
Duck	I-Device
's	I-Device
Playground	I-Device
King	B-Application
's	I-Application
Quest	I-Application
III	I-Application
:	I-Application
To	I-Application
Heir	I-Application
Is	I-Application
Human	I-Application
Space	B-Device
Quest	I-Device
:	I-Device
The	I-Device
Sarien	I-Device
Encounter	I-Device
Leisure	B-Device
Suit	I-Device
Larry	I-Device
in	I-Device
the	I-Device
Land	I-Device
of	I-Device
the	I-Device
Lounge	I-Device
Lizards	I-Device
Mixed-Up	B-Device
Mother	I-Device
Goose	I-Device
Police	B-Device
Quest	I-Device
:	I-Device
In	I-Device
Pursuit	I-Device
of	I-Device
the	I-Device
Death	I-Device
Angel	I-Device
Space	B-Device
Quest	I-Device
II	I-Device
:	I-Device
Vohaul	I-Device
's	I-Device
Revenge	I-Device
Gold	B-Device
Rush	I-Device
!	I-Device
</s>
