<s>
SCION	O
's	O
MicroAngelo	B-Device
was	O
an	O
early	O
graphics	B-Device
card	I-Device
for	O
S-100	B-Architecture
bus	I-Architecture
computers	O
.	O
</s>
<s>
Each	O
MicroAngelo	B-Device
board	O
produced	O
a	O
512	O
by	O
480	O
pixel	O
monochrome	O
image	O
,	O
high	O
resolution	O
for	O
the	O
era	O
.	O
</s>
<s>
The	O
MicroAngelo	B-Device
Palette	O
(	O
or	O
Colour	O
Mixing	O
)	O
Card	O
used	O
the	O
output	O
of	O
multiple	O
MicroAngelo	B-Device
's	O
as	O
individual	O
bit-planes	O
to	O
produce	O
images	O
with	O
up	O
to	O
256	O
colors	O
(	O
using	O
8	O
cards	O
)	O
.	O
</s>
<s>
Early	O
versions	O
of	O
AutoCAD	B-Algorithm
supported	O
the	O
MicroAngelo	B-Device
system	O
.	O
</s>
<s>
The	O
original	O
MA512	O
board	O
included	O
32kB	O
of	O
RAM	B-Architecture
for	O
the	O
frame	O
buffer	O
,	O
a	O
Z80	B-General_Concept
processor	O
operating	O
as	O
a	O
controller	O
and	O
memory	O
refresh	O
driver	O
,	O
and	O
4kB	O
of	O
ROM	B-Device
containing	O
one	O
of	O
two	O
optional	O
sets	O
of	O
subroutines	O
.	O
</s>
<s>
Users	O
programmed	O
the	O
MicroAngelo	B-Device
in	O
assembly	B-Language
language	I-Language
using	O
the	O
Z80	B-General_Concept
's	O
input/output	O
parallel	O
ports	O
,	O
which	O
sent	O
data	O
over	O
the	O
internal	O
S-100	B-Architecture
bus	I-Architecture
at	O
relatively	O
high	O
speeds	O
.	O
</s>
<s>
The	O
data	O
sent	O
over	O
the	O
bus	O
was	O
examined	O
by	O
the	O
Z80	B-General_Concept
on	O
the	O
card	O
,	O
which	O
then	O
ran	O
a	O
selected	O
subroutine	O
contained	O
in	O
its	O
ROM	B-Device
to	O
place	O
data	O
into	O
the	O
frame	O
buffer	O
.	O
</s>
<s>
The	O
screen	O
buffer	O
could	O
be	O
moved	O
to	O
or	O
from	O
the	O
computer	O
's	O
main	O
memory	O
-	O
useful	O
for	O
printing	O
when	O
pushed	O
from	O
the	O
card	O
to	O
the	O
computer	O
,	O
or	O
displaying	O
bitmap	B-Algorithm
graphics	I-Algorithm
when	O
reversed	O
.	O
</s>
<s>
The	O
4	O
kB	O
ROM	B-Device
normally	O
contained	O
"	O
Screenware	O
Pak	O
I	O
"	O
,	O
which	O
provided	O
routines	O
to	O
emulate	O
an	O
85	O
by	O
40	O
line	O
character	O
screen	O
,	O
which	O
also	O
allowed	O
the	O
user	O
to	O
define	O
their	O
own	O
12	O
by	O
6	O
pixel	O
character	O
sets	O
in	O
the	O
card	O
's	O
RAM	B-Architecture
.	O
</s>
<s>
The	O
optional	O
6	O
kB	O
"	O
Screenware	O
Pak	O
II	O
"	O
(	O
in	O
8	O
kB	O
of	O
ROM	B-Device
)	O
was	O
a	O
superset	O
of	O
Pak	O
I	O
,	O
adding	O
circle	O
,	O
line	O
and	O
polygon	O
drawing	O
routines	O
,	O
flood	O
fill	O
and	O
a	O
variety	O
of	O
other	O
features	O
.	O
</s>
<s>
This	O
made	O
expanding	O
a	O
system	O
with	O
a	O
complete	O
set	O
of	O
eight	O
MicroAngelo	B-Device
boards	O
difficult	O
,	O
because	O
the	O
eight	O
cards	O
and	O
the	O
associated	O
palette	O
card	O
would	O
end	O
up	O
using	O
up	O
the	O
vast	O
majority	O
of	O
256	O
available	O
ports	O
.	O
</s>
<s>
MicroAngelo	B-Device
also	O
supported	O
a	O
light	B-Device
pen	I-Device
,	O
connected	O
through	O
input	O
terminals	O
on	O
the	O
top	O
of	O
the	O
card	O
.	O
</s>
<s>
Screenware	O
also	O
included	O
routines	O
for	O
drawing	O
movable	O
cursors	O
in	O
hardware	O
(	O
as	O
opposed	O
to	O
bit	B-Algorithm
block	I-Algorithm
transferring	I-Algorithm
)	O
,	O
and	O
the	O
cursor	O
could	O
be	O
made	O
to	O
follow	O
the	O
light	B-Device
pen	I-Device
simply	O
by	O
reading	O
the	O
pen	O
coordinates	O
and	O
feeding	O
them	O
into	O
the	O
cursor	O
.	O
</s>
<s>
Shortly	O
after	O
the	O
MA520	O
was	O
announced	O
,	O
SCION	O
stated	O
they	O
were	O
going	O
to	O
produce	O
a	O
standalone	O
terminal	O
consisting	O
of	O
a	O
complete	O
Zilog	O
Z80-based	O
CP/M	B-Application
machine	O
packaged	O
with	O
a	O
MA520	O
,	O
and	O
optionally	O
a	O
monitor	O
as	O
well	O
.	O
</s>
<s>
Form	O
and	O
Function	O
packaged	O
a	O
graphics	O
terminal	O
using	O
a	O
single	O
MicroAngelo	B-Device
board	O
placed	O
inside	O
an	O
existing	O
Ball	O
monochrome	O
monitor	O
to	O
produce	O
the	O
"	O
IM-1	O
"	O
.	O
</s>
<s>
The	O
IM-1	O
connected	O
to	O
any	O
computer	O
using	O
a	O
serial	B-Protocol
port	I-Protocol
,	O
data	O
being	O
passed	O
along	O
to	O
the	O
cards	O
.	O
</s>
<s>
This	O
solution	O
had	O
a	O
number	O
of	O
problems	O
,	O
including	O
the	O
fact	O
that	O
it	O
did	O
not	O
support	O
existing	O
terminal	O
standards	O
like	O
VT52	B-Application
,	O
and	O
that	O
the	O
serial	B-Protocol
port	I-Protocol
would	O
start	O
to	O
bog	O
down	O
above	O
about	O
6000	O
bit/s	O
,	O
slow	O
even	O
for	O
the	O
era	O
.	O
</s>
