<s>
The	O
VIDC1	B-Device
was	O
a	O
Video	B-General_Concept
Display	I-General_Concept
Controller	I-General_Concept
chip	O
created	O
as	O
an	O
accompanying	O
chip	O
to	O
the	O
ARM	B-Architecture
CPU	O
used	O
in	O
Acorn	B-Device
Archimedes	I-Device
computer	O
systems	O
.	O
</s>
<s>
Its	O
successor	O
,	O
the	O
VIDC20	B-Device
,	O
was	O
later	O
used	O
in	O
RiscPCs	B-Device
.	O
</s>
<s>
The	O
VIDC1	B-Device
offers	O
colour	O
depths	O
of	O
1	O
,	O
2	O
,	O
4	O
or	O
eight	O
bits	O
per	O
colour	O
,	O
allowing	O
for	O
2	O
,	O
4	O
,	O
16	O
and	O
256	O
colour	O
displays	O
(	O
the	O
VIDC20	B-Device
can	O
offer	O
up	O
to	O
approximately	O
16	O
million	O
colours	O
)	O
.	O
</s>
<s>
A	O
colour	B-Data_Structure
lookup	I-Data_Structure
table	I-Data_Structure
or	O
palette	B-Data_Structure
register	O
set	O
of	O
16	O
12-bit	B-Device
words	O
was	O
provided	O
,	O
offering	O
a	O
range	O
of	O
4096	O
colours	O
for	O
each	O
of	O
the	O
colours	O
in	O
those	O
displays	O
or	O
modes	O
employing	O
up	O
to	O
16	O
colours	O
.	O
</s>
<s>
The	O
12	B-Device
bits	I-Device
were	O
split	O
in	O
three	O
4-bit	O
RGB	O
values	O
,	O
with	O
a	O
4-bit	O
high	O
speed	O
D/A	O
converter	O
for	O
each	O
of	O
the	O
three	O
primary	O
colours	O
.	O
</s>
<s>
Since	O
the	O
device	O
had	O
no	O
horizontal	B-General_Concept
sync	I-General_Concept
interrupt	O
,	O
it	O
was	O
difficult	O
to	O
display	O
additional	O
colours	O
by	O
changing	O
the	O
palette	B-Data_Structure
for	O
each	O
scan	O
line	O
,	O
but	O
not	O
impossible	O
,	O
thanks	O
to	O
the	O
2MHz	O
IOC	O
timer	O
1	O
.	O
</s>
<s>
It	O
had	O
also	O
one	O
hardware	O
32-pixel	O
wide	O
sprite	O
with	O
unlimited	O
height	O
(	O
by	O
default	O
used	O
for	O
the	O
mouse	O
pointer	O
)	O
,	O
where	O
each	O
pixel	O
is	O
coded	O
in	O
two	O
bits	O
:	O
value	O
0	O
is	O
for	O
transparency	O
,	O
and	O
the	O
three	O
others	O
are	O
freely	O
chosen	O
from	O
the	O
4096	O
colour	O
palette	B-Data_Structure
.	O
</s>
<s>
The	O
VIDC	O
also	O
supported	O
eight-channel	O
stereo	O
logarithmic	O
8-bit	O
PWM	B-Algorithm
sound	O
.	O
</s>
