<s>
The	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
(	O
HGC	O
)	O
is	O
a	O
computer	O
graphics	B-Device
controller	I-Device
formerly	O
made	O
by	O
Hercules	O
Computer	O
Technology	O
,	O
Inc	O
.	O
that	O
combines	O
IBM	O
's	O
text-only	B-Application
MDA	B-Device
display	O
standard	O
with	O
a	O
bitmapped	B-Algorithm
graphics	I-Algorithm
mode	O
,	O
also	O
offering	O
a	O
parallel	B-Device
printer	I-Device
port	I-Device
.	O
</s>
<s>
The	O
HGC	O
was	O
very	O
popular	O
,	O
and	O
became	O
a	O
widely	O
supported	O
de	O
facto	O
display	O
standard	O
on	O
IBM	B-Device
PC	I-Device
compatibles	O
.	O
</s>
<s>
The	O
HGC	O
standard	O
was	O
used	O
long	O
after	O
more	O
technically	O
capable	O
systems	O
had	O
entered	O
the	O
market	O
,	O
especially	O
on	O
dual-monitor	B-General_Concept
setups	O
.	O
</s>
<s>
The	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
was	O
released	O
to	O
fill	O
a	O
gap	O
in	O
the	O
IBM	O
video	O
product	O
lineup	O
.	O
</s>
<s>
When	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
was	O
launched	O
in	O
1981	O
,	O
it	O
had	O
two	O
graphics	B-Device
cards	I-Device
available	O
,	O
the	O
Color	B-Device
Graphics	I-Device
Adapter	I-Device
(	O
CGA	B-Device
)	O
and	O
the	O
Monochrome	B-Device
Display	I-Device
And	I-Device
Printer	I-Device
Adapter	I-Device
(	O
MDA	B-Device
)	O
.	O
</s>
<s>
CGA	B-Device
offered	O
low-resolution	O
(	O
)	O
color	O
graphics	O
and	O
medium-resolution	O
(	O
)	O
monochrome	O
graphics	O
,	O
while	O
MDA	B-Device
offers	O
a	O
sharper	O
text	B-Application
mode	I-Application
(	O
equivalent	O
to	O
)	O
but	O
has	O
no	O
per-pixel	O
addressing	O
modes	O
and	O
is	O
limited	O
to	O
a	O
fixed	O
character	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
The	O
founder	O
of	O
Hercules	O
Computer	O
Technology	O
,	O
Van	O
Suwannukul	O
,	O
created	O
the	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
so	O
that	O
he	O
could	O
work	O
on	O
his	O
doctoral	O
thesis	O
on	O
an	O
IBM	B-Device
PC	I-Device
using	O
the	O
Thai	O
alphabet	O
,	O
impossible	O
with	O
the	O
low	O
resolution	O
of	O
CGA	B-Device
or	O
the	O
fixed	O
character	B-General_Concept
set	I-General_Concept
of	O
MDA	B-Device
.	O
</s>
<s>
The	O
original	O
HGC	O
is	O
an	O
8-bit	B-Architecture
ISA	I-Architecture
card	O
with	O
64KB	O
of	O
RAM	B-Architecture
,	O
visible	O
on	O
the	O
board	O
as	O
eight	O
4164	O
RAM	B-Architecture
chips	I-Architecture
,	O
and	O
a	O
DE-9	B-Protocol
output	I-Protocol
compatible	O
with	O
the	O
IBM	B-Device
monochrome	I-Device
monitor	I-Device
used	O
with	O
the	O
MDA	B-Device
.	O
</s>
<s>
Like	O
the	O
MDA	B-Device
,	O
it	O
includes	O
a	O
parallel	B-Device
interface	I-Device
for	O
attaching	O
a	O
printer	O
.	O
</s>
<s>
The	O
video	O
output	O
is	O
5V	O
TTL	B-General_Concept
,	O
as	O
with	O
the	O
MDA	B-Device
card	I-Device
.	O
</s>
<s>
Nominally	O
,	O
the	O
Hercules	B-Device
card	I-Device
provides	O
a	O
horizontal	O
scanning	O
frequency	O
of	O
18.425	O
±	O
0.500kHz	O
,	O
and	O
50Hz	O
vertical	O
.	O
</s>
<s>
The	O
Hercules	B-Device
card	I-Device
provides	O
two	O
modes	O
:	O
</s>
<s>
The	O
text	B-Application
mode	I-Application
of	O
the	O
Hercules	B-Device
card	I-Device
uses	O
the	O
same	O
signal	O
timing	O
as	O
the	O
MDA	B-Device
text	B-Application
mode	I-Application
.	O
</s>
<s>
The	O
Hercules	B-Device
graphics	I-Device
mode	O
is	O
similar	O
to	O
the	O
CGA	B-Device
high-resolution	O
(	O
)	O
two-color	O
mode	O
;	O
the	O
video	B-Algorithm
buffer	I-Algorithm
contains	O
a	O
packed-pixel	O
bitmap	O
(	O
eight	O
pixels	O
per	O
byte	O
,	O
one	O
bit	O
per	O
pixel	O
)	O
with	O
the	O
same	O
byte	O
format	O
—	O
including	O
the	O
pixel-to-bit	O
mapping	O
and	O
byte	O
order	O
—	O
as	O
the	O
CGA	B-Device
two-color	O
graphics	O
mode	O
,	O
and	O
the	O
video	B-Algorithm
buffer	I-Algorithm
is	O
also	O
split	O
into	O
interleaved	O
banks	O
,	O
each	O
8KB	O
in	O
size	O
.	O
</s>
<s>
However	O
,	O
because	O
in	O
the	O
Hercules	B-Device
graphics	I-Device
mode	O
there	O
are	O
more	O
than	O
256	O
scanlines	O
and	O
the	O
display	O
buffer	O
size	O
is	O
nearly	O
32KB	O
(	O
instead	O
of	O
16KB	O
as	O
in	O
all	O
CGA	B-Device
graphics	I-Device
modes	O
)	O
,	O
four	O
interleaved	O
banks	O
are	O
used	O
in	O
the	O
Hercules	O
mode	O
instead	O
of	O
two	O
as	O
in	O
the	O
CGA	B-Device
modes	O
.	O
</s>
<s>
Also	O
,	O
to	O
represent	O
720	O
pixels	O
per	O
line	O
instead	O
of	O
640	O
as	O
on	O
the	O
CGA	B-Device
,	O
each	O
scanline	O
has	O
90	O
bytes	O
of	O
pixel	O
data	O
instead	O
of	O
80	O
.	O
</s>
<s>
The	O
64KB	O
RAM	B-Architecture
of	O
the	O
HGC	O
can	O
hold	O
two	O
graphics	O
display	O
pages	O
.	O
</s>
<s>
Another	O
bit	O
,	O
in	O
a	O
configuration	O
register	O
exclusive	O
to	O
the	O
HGC	O
,	O
determines	O
whether	O
the	O
second32	O
KB	O
of	O
RAM	B-Architecture
on	O
the	O
HGC	O
is	O
accessible	O
to	O
the	O
CPU	O
at	O
the	O
base	O
address	O
B8000h	O
.	O
</s>
<s>
power-on	O
)	O
so	O
that	O
the	O
card	O
does	O
not	O
conflict	O
with	O
a	O
CGA	B-Device
or	O
other	O
color	O
card	O
at	O
address	O
B8000h	O
.	O
</s>
<s>
In	O
text	B-Application
mode	I-Application
,	O
the	O
HGC	O
appears	O
exactly	O
like	O
an	O
MDA	B-Device
card	I-Device
.	O
</s>
<s>
Unlike	O
the	O
MDA	B-Device
and	O
CGA	B-Device
,	O
the	O
PC	B-Operating_System
BIOS	I-Operating_System
provides	O
no	O
intrinsic	O
support	O
for	O
the	O
HGC	O
.	O
</s>
<s>
Hercules	O
developed	O
extensions	O
,	O
called	O
HBASIC	O
,	O
for	O
IBM	B-Language
Advanced	I-Language
BASIC	I-Language
to	O
add	O
HGC	O
support	O
and	O
Hercules	B-Device
cards	I-Device
came	O
with	O
Graph	O
X	O
,	O
a	O
software	B-Library
library	I-Library
for	O
Hercules	O
graphical-mode	O
support	O
and	O
geometric	B-Algorithm
primitives	I-Algorithm
.	O
</s>
<s>
Popular	O
IBM	B-Device
PC	I-Device
programs	O
such	O
as	O
Lotus	B-Application
1-2-3	I-Application
spreadsheet	O
,	O
AutoCAD	B-Algorithm
computer-aided	O
drafting	O
,	O
Pagemaker	B-Operating_System
and	O
Xerox	B-Application
Ventura	I-Application
desktop	O
publishing	O
,	O
and	O
Microsoft	B-Application
Flight	I-Application
Simulator	I-Application
2.0	I-Application
came	O
with	O
their	O
own	O
drivers	O
to	O
use	O
the	O
Hercules	B-Device
graphics	I-Device
mode	O
.	O
</s>
<s>
Though	O
the	O
graphics	O
mode	O
of	O
the	O
Hercules	B-Device
card	I-Device
is	O
not	O
CGA-compatible	O
,	O
it	O
is	O
similar	O
enough	O
to	O
the	O
two	O
CGA	B-Device
graphics	I-Device
modes	O
that	O
with	O
the	O
use	O
of	O
third-party	O
terminate-and-stay-resident	O
programs	O
it	O
can	O
also	O
work	O
with	O
programs	O
written	O
for	O
the	O
CGA	B-Device
card	O
's	O
standard	O
graphics	O
modes	O
.	O
</s>
<s>
As	O
the	O
Hercules	B-Device
card	I-Device
does	O
not	O
actually	O
have	O
color-generating	O
circuitry	O
,	O
nor	O
can	O
it	O
connect	O
to	O
a	O
color	O
monitor	O
,	O
color	O
appears	O
as	O
simulated	O
grayscale	O
in	O
varying	O
dithering	O
patterns	O
.	O
</s>
<s>
Clones	B-General_Concept
of	O
the	O
Hercules	O
appeared	O
,	O
including	O
generic	O
models	O
at	O
very	O
low	O
prices	O
,	O
usually	O
without	O
the	O
printer	B-Device
port	I-Device
.	O
</s>
<s>
Hercules	O
advertisements	O
implied	O
that	O
use	O
of	O
generic	O
Hercules	O
clones	B-General_Concept
can	O
damage	O
the	O
monitor	O
.	O
</s>
<s>
The	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
was	O
very	O
successful	O
,	O
especially	O
after	O
Lotus	B-Application
1-2-3	I-Application
supported	O
it	O
,	O
with	O
one-half	O
million	O
units	O
sold	O
by	O
1985	O
.	O
</s>
<s>
Hercules	O
Computer	O
Technology	O
had	O
18%	O
of	O
the	O
graphics	B-Device
card	I-Device
market	O
,	O
second	O
to	O
IBM	O
.	O
</s>
<s>
Hercules-compatible	O
graphics	B-Device
cards	I-Device
shipped	O
as	O
standard	O
hardware	O
with	O
most	O
PC	O
clones	B-General_Concept
.	O
</s>
<s>
The	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
had	O
several	O
versions	O
.	O
</s>
<s>
Several	O
updated	O
versions	O
of	O
the	O
original	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
exist	O
.	O
</s>
<s>
The	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
Plus	O
or	O
HGC+	B-Device
(	O
GB112	O
)	O
was	O
released	O
in	O
June	O
1986	O
at	O
an	O
original	O
retail	O
price	O
of	O
$299	O
.	O
</s>
<s>
It	O
was	O
an	O
enhancement	O
of	O
the	O
HGC	O
,	O
adding	O
support	O
for	O
redefinable	O
fonts	O
called	O
RAMFONT	O
in	O
MDA	B-Device
compatible	O
text	B-Application
mode	I-Application
.	O
</s>
<s>
It	O
was	O
based	O
around	O
a	O
specialty	O
chip	O
designed	O
by	O
Hercules	O
Computer	O
Technology	O
,	O
unlike	O
the	O
original	O
Hercules	B-Device
Graphics	I-Device
Card	I-Device
which	O
used	O
standard	O
components	O
.	O
</s>
<s>
Software	O
support	O
included	O
Lotus	B-Application
1-2-3	I-Application
v2	I-Application
,	O
Symphony	B-Application
1.1	I-Application
,	O
Framework	B-Application
II	I-Application
and	O
Microsoft	B-Application
Word	I-Application
3	I-Application
.	O
</s>
<s>
In	O
1988	O
Hercules	O
released	O
the	O
Hercules	O
Network	O
Card	O
Plus	O
,	O
a	O
variant	O
of	O
the	O
Graphics	B-Device
Card	I-Device
Plus	O
with	O
an	O
integrated	O
TOPS/FlashTalk	O
-compatible	O
network	O
adapter	O
.	O
</s>
<s>
Like	O
the	O
HGC+	B-Device
it	O
supported	O
RAMFONT	O
,	O
but	O
lacked	O
a	O
printer	B-Device
port	I-Device
.	O
</s>
<s>
The	O
InColor	B-Device
Card	I-Device
(	O
GB222	B-Device
)	O
was	O
introduced	O
on	O
April	O
1987	O
.	O
</s>
<s>
It	O
included	O
color	O
capabilities	O
similar	O
to	O
the	O
EGA	B-Device
,	O
with	O
16	O
colors	O
from	O
a	O
palette	O
of	O
64	O
.	O
</s>
<s>
It	O
retained	O
the	O
same	O
two	O
modes	O
(	O
text	O
with	O
redefinable	O
fonts	O
and	O
graphics	O
)	O
,	O
and	O
was	O
backward	O
compatible	O
with	O
software	O
written	O
for	O
the	O
earlier	O
monochrome	O
Hercules	B-Device
cards	I-Device
.	O
</s>
<s>
The	O
Hercules	O
Color	O
Card	O
(	O
GB200	O
)	O
was	O
a	O
CGA-compatible	O
video	B-Device
board	I-Device
,	O
and	O
should	O
not	O
be	O
confused	O
with	O
the	O
InColor	B-Device
Card	I-Device
.	O
</s>
<s>
A	O
version	O
without	O
printer	B-Device
port	I-Device
exists	O
.	O
</s>
<s>
The	O
Hercules	O
Text	O
Card	O
was	O
a	O
text	O
only	O
MDA	B-Device
clone	B-General_Concept
,	O
but	O
offered	O
a	O
parallel	B-Device
printer	I-Device
port	I-Device
.	O
</s>
<s>
Certain	O
later	O
models	O
of	O
the	O
Tandy	O
1000	O
(	O
such	O
as	O
the	O
1000	O
TL	O
and	O
SL	O
)	O
and	O
the	O
Epson	B-Device
Equity	I-Device
contained	O
circuitry	O
built	O
into	O
their	O
CPU	O
boards	O
that	O
supported	O
Hercules	O
display	O
modes	O
in	O
addition	O
to	O
their	O
standard	O
CGA	B-Device
modes	O
.	O
</s>
