<s>
The	O
VIC-1211	O
Super	B-Language
Expander	I-Language
is	O
a	O
cartridge	B-Protocol
for	O
the	O
VIC-20	B-Device
home	O
computer	O
.	O
</s>
<s>
It	O
was	O
designed	O
to	O
provide	O
several	O
extensions	B-Language
to	O
the	O
BASIC	B-Language
interpreter	B-Application
on	O
the	O
computer	O
,	O
mostly	O
to	O
help	O
with	O
programming	B-General_Concept
graphics	O
and	O
sound	O
.	O
</s>
<s>
It	O
also	O
provided	O
of	O
extra	O
RAM	B-Architecture
(	O
of	O
which	O
136	O
bytes	B-Application
were	O
used	O
by	O
the	O
cartridge	B-Protocol
itself	O
)	O
.	O
</s>
<s>
The	O
cartridge	B-Protocol
was	O
created	O
by	O
Commodore	O
Business	O
Machines	O
(	O
CBM	O
)	O
and	O
released	O
in	O
1981	O
.	O
</s>
<s>
The	O
dialect	O
of	O
BASIC	B-Language
bundled	O
with	O
the	O
VIC-20	B-Device
,	O
Commodore	B-Language
BASIC	I-Language
V2.0	I-Language
,	O
was	O
notorious	O
for	O
its	O
sparse	O
functionality	O
.	O
</s>
<s>
It	O
did	O
n't	O
even	O
match	O
the	O
features	O
of	O
Commodore	O
's	O
older	O
line	O
of	O
computers	O
,	O
the	O
PET	B-Device
which	O
,	O
at	O
that	O
time	O
,	O
already	O
featured	O
Commodore	B-Language
BASIC	I-Language
version	O
4.0	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
it	O
was	O
outdated	O
by	O
the	O
VIC-20	B-Device
'	O
s	O
release	O
and	O
seemed	O
quite	O
primitive	O
compared	O
to	O
BASIC	B-Language
dialects	I-Language
available	O
on	O
other	O
microcomputers	O
.	O
</s>
<s>
To	O
be	O
fair	O
,	O
the	O
decision	O
by	O
Commodore	O
to	O
recycle	O
the	O
old	O
BASIC	B-Language
,	O
and	O
the	O
fact	O
that	O
it	O
could	O
fit	O
in	O
just	O
ROM	B-Device
(	O
including	O
the	O
KERNAL	B-Operating_System
)	O
,	O
helped	O
keep	O
the	O
VIC-20	B-Device
'	O
s	O
price	O
to	O
a	O
minimum	O
and	O
so	O
contributed	O
to	O
its	O
huge	O
success	O
.	O
</s>
<s>
Plus	O
it	O
was	O
stable	O
and	O
almost	O
entirely	O
bug-free	O
,	O
which	O
could	O
not	O
be	O
said	O
of	O
some	O
competing	O
BASICs	O
.	O
</s>
<s>
Nevertheless	O
,	O
not	O
only	O
did	O
"	O
VIC	O
BASIC	B-Language
"	O
lack	O
commands	O
considered	O
fundamental	O
to	O
the	O
BASIC	B-Language
language	I-Language
,	O
such	O
as	O
"	O
else	O
"	O
and	O
"	O
renum	O
"	O
,	O
but	O
graphics	O
and	O
sound	O
effects	O
were	O
completely	O
unsupported	O
.	O
</s>
<s>
To	O
use	O
VIC-20	B-Device
'	O
s	O
graphics	O
and	O
sound	O
programmers	O
had	O
to	O
"	O
PEEK	B-Language
and	I-Language
POKE	I-Language
"	O
bytes	B-Application
directly	O
from/to	O
the	O
VIC-20	B-Device
'	O
s	O
graphics/sound	O
hardware	O
,	O
the	O
6560	O
Video	B-General_Concept
Interface	I-General_Concept
Chip	I-General_Concept
(	O
VIC	O
)	O
.	O
</s>
<s>
This	O
made	O
programming	B-General_Concept
quite	O
tedious	O
and	O
error	O
prone	O
since	O
cryptic	O
memory	O
addresses	O
and	O
codes	O
had	O
to	O
be	O
used	O
constantly	O
,	O
mistakes	O
in	O
these	O
would	O
usually	O
crash	O
the	O
computer	O
instead	O
of	O
giving	O
an	O
error	O
message	O
,	O
and	O
many	O
statements	O
were	O
required	O
to	O
do	O
even	O
simple	O
tasks	O
.	O
</s>
<s>
Such	O
a	O
thing	O
was	O
death	O
in	O
the	O
tiny	O
RAM	B-Architecture
and	O
slow	O
interpreted	B-Application
BASIC	B-Language
paradigm	O
of	O
the	O
day	O
.	O
</s>
<s>
Programmers	O
could	O
mitigate	O
these	O
problems	O
by	O
using	O
machine	B-Language
code	I-Language
,	O
to	O
an	O
extent	O
,	O
but	O
this	O
in	O
itself	O
was	O
a	O
tedious	O
process	O
with	O
a	O
rather	O
steep	O
learning	O
curve	O
.	O
</s>
<s>
So	O
to	O
address	O
these	O
shortcomings	O
Commodore	O
created	O
the	O
Super	B-Language
Expander	I-Language
cartridge	B-Protocol
.	O
</s>
<s>
It	O
provided	O
extra	O
BASIC	B-Language
commands	O
to	O
facilitate	O
using	O
graphics	O
and	O
sound	O
on	O
the	O
VIC-20	B-Device
.	O
</s>
<s>
It	O
also	O
had	O
commands	O
to	O
read	O
the	O
joystick	B-Device
and	O
lightpen	B-Device
,	O
and	O
unlocked	O
the	O
use	O
of	O
function	B-Application
keys	I-Application
.	O
</s>
<s>
The	O
VIC-20	B-Device
did	O
not	O
support	O
high	O
resolution	O
graphics	O
directly	O
.	O
</s>
<s>
This	O
was	O
a	O
complex	O
and	O
long-winded	O
process	O
;	O
implementing	O
it	O
in	O
a	O
BASIC	B-Language
program	O
was	O
virtually	O
useless	O
due	O
to	O
the	O
execution	O
time	O
required	O
to	O
draw	O
anything	O
.	O
</s>
<s>
The	O
Super	B-Language
Expander	I-Language
took	O
care	O
of	O
all	O
the	O
hard	O
work	O
.	O
</s>
<s>
All	O
the	O
VIC-20	B-Device
'	O
s	O
16	O
colours	O
could	O
be	O
used	O
,	O
although	O
with	O
restrictions	O
due	O
to	O
limitations	O
of	O
the	O
6560	O
chip	O
.	O
</s>
<s>
Display	B-General_Concept
resolution	I-General_Concept
was	O
160×160	O
pixels	B-Algorithm
,	O
throttled	O
down	O
from	O
192×200	O
allowed	O
by	O
the	O
6560	O
chip	O
,	O
in	O
order	O
to	O
permit	O
per-pixel	O
addressability	O
.	O
</s>
<s>
The	O
VIC-20	B-Device
'	O
s	O
sound	O
capability	O
was	O
fairly	O
simplistic	O
,	O
so	O
programming	B-General_Concept
sound	O
effects	O
using	O
"	O
PEEK	B-Language
and	I-Language
POKE	I-Language
"	O
was	O
not	O
so	O
much	O
of	O
a	O
chore	O
as	O
programming	B-General_Concept
graphics	O
.	O
</s>
<s>
Even	O
so	O
,	O
the	O
Super	B-Language
Expander	I-Language
provided	O
a	O
command	B-Application
to	O
play	O
simple	O
tones	O
on	O
the	O
VIC-20	B-Device
'	O
s	O
four	O
voice	O
channels	O
,	O
and	O
to	O
control	O
the	O
volume	O
.	O
</s>
<s>
Music	B-Application
playback	O
was	O
unsupported	O
on	O
the	O
VIC-20	B-Device
;	O
the	O
usual	O
way	O
of	O
implementing	O
a	O
musical	O
note	O
was	O
to	O
play	O
a	O
tone	O
inside	O
a	O
for	B-Language
loop	I-Language
time	O
delay	O
.	O
</s>
<s>
In	O
contrast	O
,	O
with	O
Super	B-Language
Expander	I-Language
musical	O
scores	O
could	O
be	O
played	O
by	O
simply	O
PRINTing	O
a	O
string	O
of	O
characters	O
.	O
</s>
<s>
(	O
Music	B-Application
strings	O
were	O
distinguished	O
from	O
regular	O
strings	O
using	O
a	O
special	O
reverse-control-character	O
,	O
familiar	O
to	O
anyone	O
who	O
has	O
used	O
colours	O
or	O
cursor	O
controls	O
in	O
VIC-20	B-Device
programs	O
.	O
)	O
</s>
<s>
Each	O
of	O
the	O
VIC-20	B-Device
'	O
s	O
four	O
voice	O
channels	O
could	O
play	O
their	O
own	O
scores	O
simultaneously	O
,	O
giving	O
harmonious	B-Library
effects	O
which	O
could	O
be	O
striking	O
by	O
the	O
standards	O
of	O
the	O
time	O
.	O
</s>
<s>
Super	B-Language
Expander	I-Language
provided	O
commands	O
to	O
read	O
the	O
status	O
of	O
the	O
joystick	B-Device
and	O
paddles	B-Device
,	O
and	O
the	O
position	O
of	O
the	O
lightpen	B-Device
.	O
</s>
<s>
In	O
the	O
case	O
of	O
the	O
joystick	B-Device
,	O
since	O
it	O
was	O
the	O
"	O
digital	O
"	O
or	O
"	O
switch	O
"	O
type	O
,	O
further	O
bit-fiddling	O
was	O
required	O
to	O
decode	O
its	O
position	O
.	O
</s>
<s>
Ordinarily	O
the	O
VIC-20	B-Device
'	O
s	O
function	B-Application
keys	I-Application
could	O
only	O
be	O
used	O
in	O
a	O
program	O
,	O
by	O
scanning	O
for	O
the	O
appropriate	O
key	O
code	O
when	O
reading	O
the	O
keyboard	B-Device
.	O
</s>
<s>
In	O
the	O
VIC-20	B-Device
'	O
s	O
direct	B-Application
mode	I-Application
they	O
were	O
not	O
available	O
to	O
do	O
anything	O
.	O
</s>
<s>
With	O
the	O
Super	B-Language
Expander	I-Language
the	O
function	B-Application
keys	I-Application
could	O
be	O
assigned	O
to	O
execute	O
commands	O
in	O
immediate	O
mode	O
.	O
</s>
<s>
By	O
default	O
they	O
came	O
pre-programmed	O
with	O
the	O
most	O
common	O
BASIC	B-Language
commands	O
,	O
in	O
a	O
similar	O
fashion	O
to	O
GW-BASIC	B-Language
on	O
the	O
IBM	B-Device
PC	I-Device
.	O
</s>
<s>
The	O
user	O
could	O
then	O
assign	O
their	O
own	O
commands	O
,	O
or	O
any	O
arbitrary	O
string	O
in	O
fact	O
,	O
to	O
the	O
function	B-Application
keys	I-Application
.	O
</s>
<s>
The	O
following	O
are	O
the	O
main	O
limitations	O
of	O
the	O
Super	B-Language
Expander	I-Language
's	O
appeal	O
and	O
usefulness	O
.	O
</s>
<s>
Commodore	O
designed	O
the	O
Super	B-Language
Expander	I-Language
to	O
map	O
the	O
graphics	O
display	O
to	O
a	O
1024×1024	O
coordinate	O
system	O
.	O
</s>
<s>
Under	O
this	O
scheme	O
,	O
each	O
video	O
pixel	B-Algorithm
was	O
6.4	O
(	O
or	O
12.8	O
)	O
"	O
virtual	O
"	O
pixels	B-Algorithm
in	O
size	O
.	O
</s>
<s>
This	O
meant	O
that	O
in	O
order	O
to	O
place	O
pixels	B-Algorithm
in	O
exact	O
positions	O
on	O
the	O
screen	O
a	O
further	O
scaling	O
operation	O
had	O
to	O
be	O
coded	O
in	O
.	O
</s>
<s>
Similar	O
functionality	O
was	O
provided	O
on	O
BASIC	B-Language
3.5	O
and	O
7.0	O
via	O
the	O
SCALE	O
command	B-Application
,	O
but	O
in	O
these	O
versions	O
of	O
BASIC	B-Language
,	O
scaling	O
was	O
optional	O
and	O
could	O
be	O
done	O
to	O
any	O
arbitrary	O
user-specified	O
size	O
.	O
</s>
<s>
The	O
Super	B-Language
Expander	I-Language
had	O
no	O
capability	O
to	O
put	O
a	O
bitmap	O
to	O
the	O
display	O
.	O
</s>
<s>
This	O
meant	O
arbitrary	O
bitmaps	O
,	O
as	O
might	O
be	O
used	O
in	O
a	O
hi-res	O
game	O
,	O
had	O
to	O
be	O
drawn	O
pixel-by-pixel	O
.	O
</s>
<s>
The	O
slowness	O
of	O
the	O
BASIC	B-Language
interpreter	B-Application
made	O
this	O
unsuitable	O
for	O
applications	O
like	O
arcade-style	O
games	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
Super	B-Language
Expander	I-Language
's	O
capability	O
was	O
mostly	O
useful	O
for	O
shape-centric	O
drawings	O
such	O
as	O
charts	O
and	O
simple	O
pictures	O
,	O
or	O
adventure-style	O
games	O
with	O
static	O
images	O
.	O
</s>
<s>
Programs	O
written	O
using	O
the	O
extra	O
Super	B-Language
Expander	I-Language
commands	O
were	O
not	O
portable	B-Architecture
.	O
</s>
<s>
While	O
unavoidable	O
(	O
since	O
programs	O
would	O
not	O
fit	O
into	O
the	O
memory	O
of	O
an	O
unexpanded	O
VIC-20	B-Device
,	O
and	O
the	O
additional	O
BASIC	B-Language
commands	O
would	O
n't	O
be	O
recognized	O
anyway	O
)	O
.	O
</s>
<s>
A	O
user	O
needed	O
to	O
own	O
the	O
cartridge	B-Protocol
and	O
have	O
it	O
installed	O
before	O
a	O
program	O
written	O
with	O
the	O
additional	O
commands	O
would	O
run	O
.	O
</s>
<s>
Loading	B-Operating_System
the	O
program	O
onto	O
an	O
unexpanded	O
VIC-20	B-Device
gave	O
errors	O
.	O
</s>
<s>
Therefore	O
,	O
the	O
range	O
of	O
software	O
released	O
to	O
take	O
advantage	O
of	O
the	O
Super	B-Language
Expander	I-Language
's	O
capabilities	O
,	O
including	O
type-in	O
programs	O
published	O
in	O
magazines	O
,	O
was	O
very	O
small	O
.	O
</s>
<s>
In	O
spite	O
of	O
the	O
above	O
,	O
the	O
Super	B-Language
Expander	I-Language
's	O
features	O
filled	O
many	O
of	O
the	O
gaps	O
in	O
the	O
VIC-20	B-Device
'	O
s	O
programming	B-General_Concept
environment	O
.	O
</s>
