<s>
The	O
,	O
also	O
known	O
as	O
simply	O
the	O
SuperGrafx	B-General_Concept
,	O
is	O
a	O
fourth-generation	B-Application
home	B-Device
video	I-Device
game	I-Device
console	I-Device
manufactured	O
by	O
NEC	O
Home	O
Electronics	O
and	O
released	O
in	O
Japan	O
in	O
1989	O
.	O
</s>
<s>
It	O
is	O
the	O
successor	O
system	O
to	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
,	O
released	O
two	O
years	O
prior	O
.	O
</s>
<s>
Originally	O
known	O
as	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
2	O
during	O
production	O
stages	O
,	O
it	O
was	O
purported	O
as	O
a	O
true	O
16-bit	O
home	B-Device
console	I-Device
,	O
featuring	O
improved	O
graphics	O
and	O
audio	O
capabilities	O
over	O
its	O
predecessor	O
.	O
</s>
<s>
With	O
only	O
six	O
retail	O
games	O
released	O
that	O
took	O
advantage	O
of	O
the	O
console	O
's	O
hardware	O
updates	O
,	O
the	O
SuperGrafx	B-General_Concept
was	O
a	O
commercial	O
failure	O
,	O
selling	O
only	O
75,000	O
units	O
total	O
.	O
</s>
<s>
None	O
of	O
the	O
hardware	O
advancements	O
it	O
possessed	O
were	O
carried	O
over	O
to	O
later	O
PC	B-General_Concept
Engine	I-General_Concept
models	O
,	O
such	O
as	O
the	O
Duo	B-General_Concept
.	O
</s>
<s>
Compared	O
to	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
,	O
the	O
SuperGrafx	B-General_Concept
has	O
four	O
times	O
the	O
amount	O
of	O
working	O
RAM	B-Architecture
for	O
the	O
main	O
CPU	B-Device
.	O
</s>
<s>
Its	O
main	O
upgrade	O
is	O
an	O
additional	O
video	O
chip	O
with	O
its	O
own	O
video	O
RAM	B-Architecture
,	O
with	O
a	O
priority	O
controller	O
chip	O
,	O
which	O
allows	O
the	O
output	O
of	O
both	O
video	O
chips	O
to	O
be	O
combined	O
in	O
various	O
ways	O
.	O
</s>
<s>
This	O
gives	O
the	O
SuperGrafx	B-General_Concept
twice	O
as	O
many	O
on-screen	O
sprites	O
as	O
the	O
original	O
PC	B-General_Concept
Engine	I-General_Concept
and	O
support	O
for	O
two	O
independently	O
scrolling	O
background	O
layers	O
opposed	O
to	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
's	O
single	O
layer	O
.	O
</s>
<s>
Since	O
the	O
SuperGrafx	B-General_Concept
was	O
produced	O
and	O
marketed	O
as	O
an	O
upgraded	O
PC	B-General_Concept
Engine	I-General_Concept
model	O
rather	O
than	O
as	O
a	O
new	O
platform	O
,	O
it	O
was	O
backwards	O
compatible	O
with	O
standard	O
PC	B-General_Concept
Engine	I-General_Concept
HuCards	B-Device
in	O
addition	O
to	O
its	O
own	O
.	O
</s>
<s>
However	O
,	O
SuperGrafx-specific	O
HuCards	B-Device
were	O
expensive	O
compared	O
to	O
standard	O
HuCards	B-Device
,	O
in	O
some	O
cases	O
approaching	O
as	O
much	O
as	O
$110	O
USD	O
at	O
retail	O
.	O
</s>
<s>
The	O
SuperGrafx	B-General_Concept
is	O
also	O
compatible	O
with	O
the	O
CD-ROM²	O
System	O
add-on	O
(	O
via	O
the	O
ROM²	O
Adaptor	O
)	O
,	O
as	O
well	O
as	O
the	O
Super	O
CD-ROM²	O
add-on	O
.	O
</s>
<s>
No	O
CD-ROM²	O
format	O
games	O
were	O
produced	O
that	O
took	O
advantage	O
of	O
the	O
SuperGrafx	B-General_Concept
's	O
added	O
capabilities	O
.	O
</s>
<s>
The	O
CPU	B-Device
was	O
an	O
8-bit	O
HuC6280A	B-General_Concept
,	O
a	O
modified	O
65SC02	O
,	O
running	O
at	O
1.79	O
,	O
or	O
7.16MHz	O
(	O
switchable	O
by	O
software	O
)	O
.	O
</s>
<s>
Features	O
included	O
integrated	O
bankswitching	B-General_Concept
hardware	O
(	O
driving	O
a	O
21-bit	O
external	O
address	O
bus	O
from	O
a	O
6502-compatible	O
16-bit	O
address	O
bus	O
)	O
,	O
an	O
integrated	O
general-purpose	O
I/O	O
port	O
,	O
a	O
timer	O
,	O
block	O
transfer	O
instructions	O
,	O
and	O
dedicated	O
move	O
instructions	O
for	O
communicating	O
with	O
the	O
HuC6270A	B-General_Concept
VDC	O
.	O
</s>
<s>
There	O
was	O
32	O
KB	O
of	O
work	O
RAM	B-Architecture
and	O
128	O
KB	O
(	O
64	O
KB	O
per	O
HuC6270A	B-General_Concept
VDC	O
)	O
Video	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
display	O
subsystem	O
was	O
composed	O
of	O
two	O
16-bit	O
HuC6270A	B-General_Concept
Video	O
Display	O
Controllers	O
(	O
VDCs	O
)	O
,	O
one	O
HuC6202	O
Video	O
Priority	O
Controller	O
,	O
and	O
one	O
HuC6260	O
Video	O
Color	O
Encoder	O
(	O
VCE	O
)	O
.	O
</s>
<s>
The	O
HuC6270A	B-General_Concept
featured	O
Port-based	O
I/O	O
similar	O
to	O
the	O
TMS99xx	O
VDP	O
family	O
.	O
</s>
<s>
The	O
Y	O
(	O
Vertical	O
)	O
Resolution	O
was	O
also	O
variable	O
,	O
maximum	O
of	O
242	O
(	O
programmable	O
in	O
increments	O
of	O
1	O
scanline	B-Algorithm
)	O
.	O
</s>
<s>
There	O
were	O
32	O
palettes	B-Data_Structure
in	O
total	O
:	O
16	O
for	O
background	O
tiles	O
and	O
16	O
for	O
sprites	O
.	O
</s>
<s>
Each	O
sprite	O
palette	B-Data_Structure
could	O
have	O
15	O
colors	O
defined	O
,	O
and	O
had	O
one	O
transparent	O
color	O
index	O
;	O
and	O
each	O
background	O
tile	O
palette	B-Data_Structure
could	O
have	O
15	O
colors	O
defined	O
,	O
plus	O
one	O
color	O
index	O
whose	O
color	O
was	O
a	O
color	O
that	O
was	O
shared	O
across	O
all	O
background	O
tile	O
palettes	B-Data_Structure
.	O
</s>
<s>
Each	O
sprite	O
can	O
use	O
up	O
to	O
15	O
unique	O
colors	O
(	O
one	O
color	O
must	O
be	O
reserved	O
as	O
transparent	O
)	O
via	O
one	O
of	O
the	O
16	O
available	O
sprite	O
palettes	B-Data_Structure
.	O
</s>
<s>
The	O
dual	O
HuC6270A	B-General_Concept
VDCs	O
are	O
capable	O
of	O
displaying	O
2	O
sprite	O
layers	O
(	O
1	O
each	O
)	O
.	O
</s>
<s>
Each	O
layer	O
can	O
display	O
16	O
sprites	O
or	O
256	O
sprite	O
pixels	O
per	O
scanline	B-Algorithm
,	O
giving	O
the	O
combined	O
sprite	O
per	O
scanline	B-Algorithm
limit	O
of	O
32	O
sprites	O
or	O
512	O
sprite	O
pixels	O
.	O
</s>
<s>
Tiles	O
were	O
8x8	O
with	O
each	O
background	O
tile	O
able	O
to	O
use	O
up	O
to	O
16	O
unique	O
colors	O
via	O
one	O
of	O
the	O
16	O
available	O
background	O
palettes	B-Data_Structure
.	O
</s>
<s>
The	O
first	O
color	O
entry	O
of	O
each	O
background	O
palette	B-Data_Structure
must	O
be	O
the	O
same	O
across	O
all	O
background	O
palettes	B-Data_Structure
.	O
</s>
<s>
Six	O
Wavetable	O
Synthesis	O
audio	O
channels	O
,	O
programmable	O
through	O
the	O
HuC6280A	B-General_Concept
CPU	B-Device
.	O
</s>
<s>
Each	O
channel	O
also	O
was	O
allotted	O
20	O
bytes	O
(	O
32×5	O
bits	O
)	O
of	O
RAM	B-Architecture
for	O
sample	O
data	O
.	O
</s>
<s>
When	O
a	O
channel	O
is	O
in	O
D/A	O
mode	O
the	O
frequency	O
is	O
as	O
fast	O
as	O
the	O
CPU	B-Device
can	O
stream	O
bytes	O
to	O
the	O
port	O
,	O
though	O
in	O
practicality	O
it	O
is	O
limited	O
to	O
6.99kHz	O
when	O
using	O
the	O
TIMER	O
interrupt	O
with	O
its	O
smallest	O
loop	O
setting	O
(	O
1023	O
cpu	B-Device
cycles	O
)	O
or	O
15.7kHz	O
using	O
the	O
scanline	B-Algorithm
interrupt	O
.	O
</s>
<s>
The	O
addition	O
of	O
the	O
CD-ROM	B-Device
peripheral	O
adds	O
CD-DA	O
sound	O
,	O
and	O
a	O
single	O
ADPCM	B-Algorithm
channel	O
to	O
the	O
existing	O
sound	O
capabilities	O
of	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
.	O
</s>
<s>
The	O
SuperGrafx	B-General_Concept
is	O
backwards	O
compatible	O
with	O
all	O
standard	O
PC	B-General_Concept
Engine	I-General_Concept
HuCard-format	O
games	O
in	O
addition	O
to	O
its	O
own	O
.	O
</s>
<s>
The	O
labels	O
on	O
SuperGrafx	B-General_Concept
HuCards	B-Device
were	O
upside-down	O
relative	O
to	O
standard	O
HuCards	B-Device
;	O
A	O
standard	O
HuCard	B-Device
will	O
read	O
upside	O
down	O
on	O
a	O
SuperGrafx	B-General_Concept
,	O
while	O
its	O
own	O
are	O
right-side-up	O
.	O
</s>
<s>
The	O
SuperGrafx	B-General_Concept
is	O
also	O
compatible	O
with	O
the	O
CD-ROM²	O
and	O
Super	O
CD-ROM²	O
System	O
add-ons	O
,	O
allowing	O
it	O
to	O
play	O
any	O
CD-ROM²	O
format	O
game	O
with	O
the	O
required	O
System	O
Card	O
.	O
</s>
<s>
No	O
SuperGrafx-specific	O
CD-ROM²	O
titles	O
were	O
produced	O
.	O
</s>
<s>
The	O
SuperGrafx	B-General_Concept
is	O
compatible	O
with	O
all	O
standard	O
PC	B-General_Concept
Engine	I-General_Concept
input	O
devices	O
,	O
such	O
as	O
the	O
TurboPad	O
and	O
the	O
Multitap	O
.	O
</s>
<s>
The	O
ROM²	O
Adaptor	O
(	O
RAU-30	O
)	O
was	O
an	O
adapter	O
released	O
in	O
Japan	O
on	O
20	O
April	O
1990	O
that	O
allows	O
the	O
SuperGrafx	B-General_Concept
unit	O
to	O
be	O
connected	O
into	O
the	O
CD-ROM²	O
System	O
Interface	O
Unit	O
.	O
</s>
<s>
This	O
was	O
not	O
required	O
for	O
the	O
later	O
Super	O
CD-ROM²	O
System	O
add-on	O
.	O
</s>
<s>
Power	O
Console	O
(	O
PI-PD7	O
)	O
was	O
an	O
unreleased	O
cockpit-sized	O
controller	O
that	O
attaches	O
onto	O
the	O
SuperGrafx	B-General_Concept
unit	O
itself	O
,	O
connecting	O
via	O
the	O
expansion	O
port	O
on	O
the	O
front	O
side	O
.	O
</s>
<s>
The	O
peripheral	O
would	O
have	O
added	O
numerous	O
control	O
options	O
such	O
as	O
an	O
eight-way	O
joystick	O
,	O
four	O
action	O
buttons	O
,	O
a	O
flight	O
yoke	O
with	O
two	O
triggers	O
(	O
one	O
on	O
each	O
handle	O
)	O
,	O
a	O
throttle	O
lever	O
,	O
a	O
jog	B-Device
dial	I-Device
,	O
three	O
mode	O
switches	O
,	O
an	O
LCD	O
panel	O
,	O
an	O
LED	O
indicator	O
,	O
four	O
additional	O
controller	O
ports	O
and	O
a	O
numerical	O
keypad	O
.	O
</s>
<s>
The	O
Power	O
Console	O
was	O
scheduled	O
to	O
be	O
released	O
in	O
Spring	O
1990	O
with	O
a	O
suggested	O
retail	O
price	O
of	O
59,800	O
yen	O
,	O
but	O
was	O
never	O
released	O
due	O
to	O
its	O
high	O
production	O
cost	O
and	O
the	O
poor	O
sales	O
of	O
the	O
SuperGrafx	B-General_Concept
itself	O
.	O
</s>
<s>
There	O
were	O
only	O
five	O
SuperGrafx-specific	O
HuCards	B-Device
produced	O
.	O
</s>
<s>
In	O
addition	O
to	O
these	O
fives	O
games	O
,	O
NEC	O
Avenue	O
also	O
released	O
Darius	O
Plus	O
as	O
a	O
standard	O
PC	B-General_Concept
Engine	I-General_Concept
HuCard	B-Device
that	O
offered	O
slight	O
enhancements	O
when	O
played	O
on	O
a	O
SuperGrafx	B-General_Concept
console	O
.	O
</s>
<s>
As	O
such	O
,	O
it	O
was	O
the	O
only	O
commercially-released	O
HuCard	B-Device
game	O
to	O
carry	O
the	O
PC-SG	O
mark	O
.	O
</s>
<s>
Many	O
of	O
the	O
games	O
that	O
were	O
announced	O
for	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
SuperGrafx	I-General_Concept
were	O
either	O
canceled	O
or	O
repurposed	O
into	O
other	O
formats	O
.	O
</s>
<s>
One	O
notable	O
example	O
was	O
the	O
PC	B-General_Concept
Engine	I-General_Concept
port	O
of	O
Strider	B-Application
Hiryu	I-Application
,	O
which	O
was	O
initially	O
announced	O
as	O
a	O
SuperGrafx	B-General_Concept
title	O
,	O
but	O
was	O
ultimately	O
released	O
as	O
an	O
Arcade	O
CD-ROM²	O
disc	O
.	O
</s>
