<s>
Hellcats	B-Application
over	I-Application
the	I-Application
Pacific	I-Application
is	O
a	O
flight	B-Application
simulator	I-Application
computer	O
game	O
for	O
the	O
Macintosh	B-Device
computer	O
.	O
</s>
<s>
The	O
graphics	B-Device
engine	I-Device
was	O
combined	O
with	O
a	O
simple	O
Mac	O
interface	O
,	O
a	O
set	O
of	O
randomized	O
missions	O
,	O
and	O
a	O
number	O
of	O
technical	O
features	O
that	O
greatly	O
enhanced	O
the	O
game	O
's	O
playability	O
and	O
made	O
it	O
a	O
lasting	O
favorite	O
into	O
the	O
mid-1990s	O
.	O
</s>
<s>
After	O
the	O
release	O
of	O
Leyte	O
Gulf	O
,	O
ParSoft	O
began	O
work	O
on	O
another	O
flight	B-Application
simulator	I-Application
for	O
Graphics	O
Simulations	O
,	O
based	O
around	O
the	O
McDonnell	O
Douglas	O
F/A	O
-18	O
Hornet	O
.	O
</s>
<s>
ParSoft	O
began	O
work	O
on	O
a	O
new	O
networked	O
flight	B-Application
simulator	I-Application
that	O
would	O
emerge	O
years	O
later	O
as	O
A-10	B-Application
Attack	I-Application
!	I-Application
</s>
<s>
and	O
followed	O
by	O
its	O
own	O
missions	O
expansion	O
,	O
A-10	B-Application
Cuba	I-Application
.	O
</s>
<s>
They	O
also	O
licensed	O
the	O
basic	O
flight	O
engine	O
to	O
another	O
group	O
of	O
programmers	O
,	O
who	O
used	O
it	O
as	O
the	O
basis	O
for	O
early	O
versions	O
of	O
the	O
online	O
game	O
,	O
WarBirds	B-Protocol
.	O
</s>
<s>
Hellcats	O
is	O
a	O
combat	O
simulation	O
of	O
the	O
F6F	O
Hellcat	O
aircraft	O
in	O
a	O
series	O
of	O
fictional	O
missions	O
during	O
1943	O
's	O
Guadalcanal	B-Application
Campaign	I-Application
.	O
</s>
<s>
Primary	O
flight	O
control	O
for	O
roll	O
and	O
pitch	O
was	O
normally	O
handled	O
by	O
the	O
mouse	B-Device
,	O
which	O
included	O
a	O
scaler	O
that	O
improved	O
the	O
"	O
feel	O
"	O
,	O
although	O
the	O
flight	O
engine	O
was	O
also	O
fairly	O
insensitive	O
to	O
overcontrol	O
.	O
</s>
<s>
Joysticks	B-Device
could	O
also	O
be	O
used	O
,	O
but	O
were	O
supported	O
via	O
"	O
mouse	B-Device
mapping	O
"	O
,	O
not	O
directly	O
.	O
</s>
<s>
Some	O
missions	O
included	O
"	O
friendly	O
"	O
F6F	O
's	O
and	O
a	O
B-17	B-Application
Flying	I-Application
Fortress	I-Application
.	O
</s>
<s>
Ground	O
targets	O
included	O
AA	O
guns	O
,	O
cruisers	O
,	O
battleships	B-Application
,	O
aircraft	O
carriers	O
,	O
and	O
sometimes	O
static	O
aircraft	O
parked	O
at	O
the	O
airbases	O
.	O
</s>
<s>
This	O
was	O
a	O
bone	O
of	O
contention	O
among	O
players	O
,	O
as	O
the	O
system	O
for	O
deciding	O
whether	O
or	O
not	O
the	O
pilot	O
was	O
lost	O
was	O
completely	O
random	O
;	O
even	O
landing	O
in	O
the	O
middle	O
of	O
a	O
friendly	O
airbase	O
would	O
often	O
result	O
in	O
a	O
dialog	O
stating	O
the	O
search	O
and	O
rescue	O
teams	O
could	O
not	O
find	O
you	O
,	O
leaving	O
that	O
pilot	O
MIA	B-Application
.	O
</s>
<s>
This	O
resulted	O
in	O
a	O
game	O
that	O
was	O
much	O
more	O
approachable	O
than	O
its	O
more	O
complex	O
follow-ons	O
,	O
and	O
Hellcats	O
was	O
widely	O
enjoyed	O
by	O
players	O
that	O
would	O
not	O
normally	O
play	O
flight	B-Application
simulators	I-Application
.	O
</s>
<s>
The	O
Hellcats	O
engine	O
was	O
based	O
on	O
an	O
idea	O
Eric	O
Parker	O
formulated	O
while	O
studying	O
the	O
SPARCstation	B-Architecture
1	I-Architecture
.	O
</s>
<s>
The	O
SPARCstation	O
allowed	O
the	O
memory	O
of	O
the	O
graphics	B-Device
card	I-Device
to	O
be	O
mapped	O
into	O
main	O
memory	O
;	O
any	O
data	O
the	O
CPU	O
placed	O
in	O
those	O
memory	O
locations	O
would	O
automatically	O
be	O
copied	O
over	O
the	O
SBus	B-Architecture
to	O
a	O
frame	B-Algorithm
buffer	I-Algorithm
on	O
the	O
graphics	B-Device
card	I-Device
which	O
the	O
card	O
periodically	O
drew	O
to	O
the	O
screen	O
.	O
</s>
<s>
This	O
method	O
of	O
access	O
allowed	O
the	O
card	O
to	O
continually	O
refresh	O
the	O
screen	O
without	O
interrupting	O
the	O
CPU	O
;	O
if	O
the	O
two	O
shared	B-Operating_System
the	I-Operating_System
memory	I-Operating_System
directly	I-Operating_System
,	O
it	O
can	O
lead	O
to	O
contention	O
issues	O
that	O
will	O
slow	O
overall	O
performance	O
.	O
</s>
<s>
However	O
,	O
the	O
path	O
between	O
the	O
main	O
memory	O
and	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
was	O
relatively	O
slow	O
,	O
so	O
while	O
both	O
the	O
CPU	O
and	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
could	O
move	O
memory	O
quickly	O
within	O
their	O
own	O
private	O
memory	O
,	O
they	O
could	O
not	O
easily	O
communicate	O
those	O
changes	O
.	O
</s>
<s>
Specifically	O
,	O
the	O
CPU	O
could	O
create	O
40	O
MB/s	O
of	O
data	O
in	O
main	O
memory	O
,	O
but	O
this	O
could	O
only	O
be	O
copied	O
to	O
the	O
frame	B-Algorithm
buffer	I-Algorithm
at	O
5	O
MB/s	O
.	O
</s>
<s>
He	O
came	O
up	O
with	O
the	O
idea	O
of	O
having	O
two	O
frame	B-Algorithm
buffers	I-Algorithm
in	O
main	O
memory	O
,	O
one	O
for	O
the	O
current	O
frame	O
,	O
and	O
one	O
for	O
the	O
next	O
frame	O
to	O
be	O
displayed	O
.	O
</s>
<s>
By	O
comparing	O
the	O
two	O
frames	O
,	O
the	O
differences	O
could	O
be	O
extracted	O
,	O
and	O
only	O
those	O
copied	O
into	O
the	O
memory-mapped	O
frame	B-Algorithm
buffer	I-Algorithm
.	O
</s>
<s>
The	O
frame	B-Algorithm
buffer	I-Algorithm
on	O
the	O
card	O
thus	O
held	O
a	O
composite	O
of	O
all	O
the	O
frames	O
ever	O
drawn	O
,	O
which	O
was	O
identical	O
to	O
the	O
most	O
recent	O
image	O
in	O
the	O
computer	O
.	O
</s>
<s>
This	O
limited	O
the	O
engine	O
to	O
polygon-based	B-Algorithm
flat-shaded	I-Algorithm
graphics	I-Algorithm
.	O
</s>
<s>
Parker	O
had	O
always	O
been	O
interested	O
in	O
flight	B-Application
simulators	I-Application
and	O
started	O
adapting	O
the	O
basic	O
graphics	B-Device
engine	I-Device
as	O
the	O
core	O
of	O
a	O
new	O
game	O
.	O
</s>
<s>
At	O
lower	O
resolutions	O
the	O
amount	O
of	O
data	O
that	O
had	O
to	O
move	O
over	O
the	O
bus	O
was	O
limited	O
in	O
any	O
case	O
,	O
so	O
the	O
"	O
brute	O
force	O
"	O
approach	O
of	O
drawing	O
every	O
frame	O
to	O
the	O
buffer	O
would	O
work	O
fine	O
,	O
and	O
did	O
for	O
contemporary	O
games	O
like	O
Red	B-Device
Baron	I-Device
.	O
</s>
<s>
With	O
the	O
graphics	B-Device
engine	I-Device
in	O
place	O
,	O
what	O
was	O
left	O
was	O
to	O
take	O
the	O
engine	O
and	O
use	O
it	O
to	O
produce	O
a	O
game	O
.	O
</s>
<s>
The	O
low	O
CPU	O
cost	O
of	O
the	O
graphics	B-Device
engine	I-Device
left	O
the	O
CPU	O
with	O
ample	O
free	O
time	O
.	O
</s>
<s>
This	O
led	O
to	O
a	O
number	O
of	O
behaviors	O
that	O
would	O
be	O
impossible	O
otherwise	O
,	O
notably	O
dive	B-Application
bombing	I-Application
at	O
hundreds	O
of	O
miles	O
an	O
hour	O
followed	O
by	O
dropping	O
the	O
flaps	O
to	O
allow	O
a	O
multi-tens-of-gee	O
pullout	O
.	O
</s>
<s>
In	O
comparison	O
,	O
games	O
like	O
Red	B-Device
Baron	I-Device
had	O
hundreds	O
of	O
missions	O
,	O
and	O
while	O
they	O
played	O
exactly	O
the	O
same	O
every	O
time	O
,	O
there	O
were	O
so	O
many	O
of	O
them	O
there	O
was	O
less	O
of	O
a	O
problem	O
with	O
lack	O
of	O
novelty	O
.	O
</s>
<s>
7	O
most	O
influential	O
Mac	O
game	O
of	O
all	O
time	O
,	O
according	O
to	O
Inside	B-Application
Mac	I-Application
Games	I-Application
.	O
</s>
<s>
Tweaks	O
to	O
the	O
graphics	B-Device
engine	I-Device
provided	O
even	O
better	O
performance	O
,	O
allowing	O
more	O
cycles	O
to	O
be	O
spent	O
on	O
other	O
tasks	O
.	O
</s>
<s>
GraphSim	O
also	O
retained	O
the	O
rights	O
to	O
the	O
version	O
of	O
the	O
software	O
they	O
had	O
at	O
the	O
time	O
,	O
and	O
later	O
licensed	O
the	O
graphical	O
engine	O
to	O
be	O
used	O
in	O
the	O
early	O
versions	O
of	O
WarBirds	B-Protocol
.	O
</s>
<s>
Aware	O
that	O
the	O
major	O
problems	O
in	O
the	O
original	O
engine	O
were	O
the	O
lack	O
of	O
realistic	O
structural	O
physics	O
and	O
pilot	O
effects	O
,	O
Parsoft	O
's	O
new	O
A-10	B-Application
Attack	I-Application
!	I-Application
</s>
<s>
The	O
VBE	O
system	O
was	O
used	O
by	O
Parsoft	O
to	O
produce	O
A-10	B-Application
Cuba	I-Application
,	O
a	O
new	O
mission	O
set	O
taking	O
place	O
at	O
and	O
around	O
Guantánamo	O
Bay	O
.	O
</s>
<s>
Power	O
Unlimited	O
gave	O
a	O
review	O
score	O
of	O
95%	O
writing	O
:	O
"	O
Other	O
flight	B-Application
simulators	I-Application
dwarfed	O
Hellcats	B-Application
over	I-Application
the	I-Application
Pacific	I-Application
when	O
it	O
came	O
out	O
.	O
</s>
