<s>
Systems	B-Language
Programming	I-Language
Language	I-Language
,	O
often	O
shortened	O
to	O
SPL	B-Language
but	O
sometimes	O
known	O
as	O
SPL/3000	O
,	O
was	O
a	O
procedurally-oriented	B-Application
programming	O
language	O
written	O
by	O
Hewlett-Packard	O
for	O
the	O
HP	B-Device
3000	I-Device
minicomputer	B-Architecture
line	O
and	O
first	O
introduced	O
in	O
1972	O
.	O
</s>
<s>
SPL	B-Language
was	O
used	O
to	O
write	O
the	O
HP	B-Device
3000	I-Device
's	O
primary	O
operating	B-General_Concept
system	I-General_Concept
,	O
Multi-Programming	B-Operating_System
Executive	I-Operating_System
(	O
MPE	O
)	O
.	O
</s>
<s>
Similar	O
languages	O
on	O
other	O
platforms	O
were	O
generically	O
referred	O
to	O
as	O
system	B-Language
programming	I-Language
languages	I-Language
,	O
confusing	O
matters	O
.	O
</s>
<s>
Originally	O
known	O
as	O
Alpha	O
Systems	B-Language
Programming	I-Language
Language	I-Language
,	O
named	O
for	O
the	O
development	O
project	O
that	O
produced	O
the	O
3000-series	O
,	O
SPL	B-Language
was	O
designed	O
to	O
take	O
advantage	O
of	O
the	O
Alpha	O
's	O
stack-based	B-Application
processor	I-Application
design	O
.	O
</s>
<s>
It	O
is	O
patterned	O
on	O
ESPOL	B-Language
,	O
a	O
similar	O
ALGOL-derived	O
language	O
used	O
by	O
the	O
Burroughs	B-Device
B5000	I-Device
mainframe	B-Architecture
systems	O
,	O
which	O
also	O
influenced	O
a	O
number	O
of	O
1960s	O
languages	O
like	O
PL360	B-Language
and	O
JOVIAL	B-Language
.	O
</s>
<s>
Through	O
the	O
mid-1970s	O
,	O
the	O
success	O
of	O
the	O
HP	O
systems	O
produced	O
a	O
number	O
of	O
SPL	B-Language
offshoots	O
.	O
</s>
<s>
Examples	O
include	O
ZSPL	O
for	O
the	O
Zilog	B-General_Concept
Z80	I-General_Concept
processor	O
,	O
and	O
Micro-SPL	O
for	O
the	O
Xerox	B-Device
Alto	I-Device
.	O
</s>
<s>
The	O
later	O
inspired	O
Action	B-Language
!	I-Language
</s>
<s>
for	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
,	O
which	O
was	O
fairly	O
successful	O
.	O
</s>
<s>
The	O
latter	O
more	O
closely	O
followed	O
Pascal	B-Application
syntax	O
,	O
losing	O
some	O
of	O
SPL	B-Language
's	O
idiosyncrasies	O
.	O
</s>
<s>
SPL	B-Language
was	O
widely	O
used	O
during	O
the	O
lifetime	O
of	O
the	O
original	O
integrated	O
circuit-based	O
versions	O
HP	B-Device
3000	I-Device
platform	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
the	O
HP	B-Device
3000	I-Device
and	O
MPE	O
were	O
reimplemented	O
in	O
an	O
emulator	B-Application
running	O
on	O
the	O
PA-RISC-based	O
HP	B-Device
9000	I-Device
platforms	O
.	O
</s>
<s>
HP	O
promoted	O
Pascal	B-Application
as	O
the	O
favored	O
system	O
language	O
on	O
PA-RISC	B-Device
and	O
did	O
not	O
provide	O
an	O
SPL	B-Language
compiler	B-Language
.	O
</s>
<s>
This	O
caused	O
code	O
maintenance	O
concerns	O
,	O
and	O
3rd	O
party	O
SPL	B-Language
compilers	B-Language
were	O
introduced	O
to	O
fill	O
this	O
need	O
.	O
</s>
<s>
Hewlett-Packard	O
introduced	O
their	O
first	O
minicomputers	B-Architecture
,	O
the	O
HP	B-Device
2100	I-Device
series	O
,	O
in	O
1967	O
.	O
</s>
<s>
During	O
this	O
period	O
,	O
the	O
concept	O
of	O
time	B-General_Concept
sharing	I-General_Concept
was	O
becoming	O
popular	O
,	O
especially	O
as	O
core	B-General_Concept
memory	I-General_Concept
costs	O
fell	O
and	O
systems	O
began	O
to	O
ship	O
with	O
more	O
memory	O
.	O
</s>
<s>
In	O
1968	O
,	O
HP	O
introduced	O
a	O
bundled	O
system	O
using	O
two	O
2100-series	O
machine	O
running	O
HP	B-Language
Time-Shared	I-Language
BASIC	I-Language
,	O
which	O
provided	O
a	O
complete	O
operating	B-General_Concept
system	I-General_Concept
as	O
well	O
as	O
the	O
BASIC	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
HP	O
BASIC	O
was	O
highly	O
influential	O
for	O
many	O
years	O
,	O
and	O
its	O
syntax	O
can	O
be	O
seen	O
in	O
a	O
number	O
microcomputer	B-Architecture
BASICs	O
,	O
including	O
Palo	O
Alto	B-Device
TinyBASIC	O
,	O
Integer	B-Language
BASIC	I-Language
,	O
North	B-Language
Star	I-Language
BASIC	I-Language
,	O
Atari	B-Language
BASIC	I-Language
,	O
and	O
others	O
.	O
</s>
<s>
Designers	O
at	O
HP	O
began	O
to	O
wonder	O
"	O
If	O
we	O
can	O
produce	O
a	O
time-sharing	B-General_Concept
system	I-General_Concept
this	O
good	O
using	O
a	O
junky	O
computer	O
like	O
the	O
2116	O
,	O
think	O
what	O
we	O
could	O
accomplish	O
if	O
we	O
designed	O
our	O
own	O
computer.	O
"	O
</s>
<s>
New	O
team	O
members	O
included	O
those	O
who	O
had	O
worked	O
on	O
Burroughs	O
and	O
IBM	O
mainframe	B-Architecture
systems	O
,	O
and	O
the	O
resulting	O
concepts	O
bore	O
a	O
strong	O
resemblance	O
to	O
the	O
highly	O
successful	O
Burroughs	B-Device
B5000	I-Device
system	O
.	O
</s>
<s>
The	O
B5000	O
used	O
a	O
stack	B-Application
machine	I-Application
processor	O
that	O
made	O
multiprogramming	O
simpler	O
to	O
implement	O
,	O
and	O
this	O
same	O
architecture	O
was	O
also	O
selected	O
for	O
the	O
new	O
HP	O
concept	O
.	O
</s>
<s>
Two	O
implementations	O
were	O
considered	O
,	O
a	O
32-bit	O
mainframe-scale	O
machine	O
known	O
as	O
Omega	O
,	O
and	O
a	O
16-bit	O
design	O
known	O
as	O
Alpha	O
.	O
</s>
<s>
This	O
led	O
to	O
an	O
extensive	O
redesign	O
of	O
Alpha	O
to	O
differentiate	O
it	O
from	O
the	O
2100	O
's	O
,	O
and	O
it	O
eventually	O
emerged	O
with	O
plans	O
for	O
an	O
even	O
more	O
aggressive	O
operating	B-General_Concept
system	I-General_Concept
design	O
.	O
</s>
<s>
Omega	O
had	O
intended	O
to	O
run	O
in	O
batch	B-General_Concept
mode	I-General_Concept
and	O
use	O
a	O
smaller	O
computer	O
,	O
the	O
"	O
front	O
end	O
"	O
,	O
to	O
process	O
interactions	O
with	O
the	O
user	O
.	O
</s>
<s>
However	O
,	O
yet-another-2000	O
would	O
not	O
be	O
enough	O
for	O
Alpha	O
,	O
and	O
the	O
decision	O
was	O
made	O
to	O
have	O
a	O
single	O
operating	O
for	O
batch	O
,	O
interactive	O
and	O
even	O
real	B-General_Concept
time	I-General_Concept
operation	O
.	O
</s>
<s>
To	O
make	O
this	O
work	O
,	O
it	O
needed	O
an	O
advanced	O
computer	B-General_Concept
bus	I-General_Concept
design	O
with	O
extensive	O
direct	B-General_Concept
memory	I-General_Concept
access	I-General_Concept
(	O
DMA	O
)	O
and	O
required	O
an	O
advanced	O
operating	B-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
to	O
provide	O
quick	O
responses	O
to	O
user	O
actions	O
.	O
</s>
<s>
The	O
B5000	O
was	O
also	O
unique	O
,	O
for	O
its	O
time	O
,	O
in	O
that	O
its	O
operating	B-General_Concept
system	I-General_Concept
and	O
core	O
utilities	O
were	O
all	O
programmed	O
in	O
a	O
high-level	B-Language
language	I-Language
,	O
ESPOL	B-Language
.	O
</s>
<s>
ESPOL	B-Language
was	O
a	O
derivative	O
of	O
the	O
ALGOL	B-Language
language	I-Language
tuned	O
to	O
work	O
on	O
the	O
B5000	O
's	O
,	O
a	O
concept	O
that	O
was	O
highly	O
influential	O
in	O
the	O
1960s	O
and	O
led	O
to	O
new	O
languages	O
like	O
JOVIAL	B-Language
,	O
PL/360	B-Language
and	O
BCPL	B-Language
.	O
</s>
<s>
The	O
HP	O
team	O
decided	O
they	O
would	O
also	O
use	O
an	O
ALGOL-derived	O
language	O
for	O
their	O
operating	B-General_Concept
systems	I-General_Concept
work	O
.	O
</s>
<s>
HP	O
's	O
similar	O
language	O
was	O
initially	O
known	O
as	O
the	O
Alpha	O
Systems	B-Language
Programming	I-Language
Language	I-Language
.	O
</s>
<s>
Alpha	O
took	O
several	O
years	O
to	O
develop	O
before	O
emerging	O
in	O
1972	O
as	O
the	O
HP	B-Device
3000	I-Device
.	O
</s>
<s>
A	O
major	O
upgrade	O
to	O
the	O
entire	O
system	O
,	O
the	O
CX	O
machine	O
,	O
and	O
MPE-C	O
to	O
run	O
on	O
it	O
,	O
reformed	O
its	O
image	O
and	O
the	O
3000	O
went	O
on	O
to	O
be	O
another	O
major	O
success	O
during	O
the	O
second	O
half	O
of	O
the	O
1970s	O
.	O
</s>
<s>
This	O
success	O
made	O
SPL	B-Language
almost	O
as	O
widespread	O
as	O
the	O
2000	O
series	O
 '	O
BASIC	O
,	O
and	O
like	O
that	O
language	O
,	O
SPL	B-Language
resulted	O
in	O
a	O
number	O
of	O
versions	O
for	O
other	O
platforms	O
.	O
</s>
<s>
Notable	O
among	O
them	O
was	O
Micro-SPL	O
,	O
a	O
version	O
written	O
for	O
the	O
Xerox	B-Device
Alto	I-Device
workstation	O
.	O
</s>
<s>
This	O
machine	O
had	O
originally	O
used	O
BCPL	B-Language
as	O
its	O
primary	O
language	O
,	O
but	O
dissatisfaction	O
with	O
its	O
performance	O
led	O
Henry	O
Baker	O
to	O
design	O
a	O
non-recursive	O
language	O
that	O
he	O
implemented	O
with	O
Clinton	O
Parker	O
in	O
1979	O
.	O
</s>
<s>
Clinton	O
would	O
then	O
further	O
modify	O
Micro-SPL	O
to	O
produce	O
Action	B-Language
!	I-Language
</s>
<s>
for	O
the	O
Atari	B-Device
8-bit	I-Device
family	I-Device
in	O
1983	O
.	O
</s>
<s>
HP	O
reimplemented	O
the	O
HP	B-Device
3000	I-Device
system	O
on	O
the	O
PA-RISC	B-Device
chipset	O
,	O
running	O
a	O
new	O
version	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
known	O
as	O
MPE/iX	B-Operating_System
.	O
</s>
<s>
MPE/iX	B-Operating_System
had	O
two	O
modes	O
,	O
in	O
"	O
native	O
mode	O
"	O
it	O
ran	O
applications	O
that	O
had	O
been	O
recompiled	B-Language
for	O
the	O
PA-RISC	B-Device
using	O
newer	O
Pascal	B-Application
compilers	B-Language
,	O
while	O
under	O
"	O
compatible	O
mode	O
"	O
it	O
could	O
run	O
all	O
existing	O
software	O
via	O
emulation	B-Application
.	O
</s>
<s>
HP	O
did	O
not	O
supply	O
a	O
native	O
mode	O
compiler	B-Language
for	O
MPE/iX	B-Operating_System
so	O
it	O
was	O
not	O
an	O
easy	O
process	O
to	O
move	O
existing	O
software	O
to	O
the	O
new	O
platform	O
.	O
</s>
<s>
To	O
fill	O
the	O
need	O
,	O
Allegro	O
Consultants	O
wrote	O
an	O
SPL-compatible	O
language	O
named	O
"	O
SPLash	O
!	O
"	O
</s>
<s>
that	O
could	O
compile	B-Language
to	O
original	O
HP	B-Device
3000	I-Device
code	O
to	O
run	O
within	O
the	O
emulator	B-Application
,	O
or	O
to	O
native	O
mode	O
.	O
</s>
<s>
This	O
offered	O
a	O
porting	O
pathway	O
for	O
existing	O
SPL	B-Language
software	O
.	O
</s>
<s>
SPL	B-Language
generally	O
follows	O
ALGOL	B-Language
60	I-Language
syntax	O
conventions	O
,	O
and	O
will	O
be	O
familiar	O
to	O
anyone	O
with	O
experience	O
in	O
ALGOL	B-Language
or	O
its	O
descendants	O
,	O
like	O
Pascal	B-Application
and	O
Modula-2	B-Language
.	O
</s>
<s>
Statements	O
are	O
grouped	O
into	O
blocks	O
using	O
BEGIN	O
and	O
END	O
,	O
although	O
,	O
as	O
in	O
Pascal	B-Application
,	O
the	O
END	O
of	O
a	O
program	O
must	O
be	O
followed	O
by	O
a	O
period	O
.	O
</s>
<s>
The	O
program	O
as	O
a	O
whole	O
is	O
surrounded	O
by	O
BEGIN	O
and	O
END.	O
,	O
similar	O
to	O
Pascal	B-Application
,	O
but	O
lacking	O
a	O
PROGRAM	O
keyword	O
or	O
similar	O
statement	O
at	O
the	O
top	O
.	O
</s>
<s>
The	O
reason	O
for	O
this	O
is	O
that	O
SPL	B-Language
allows	O
any	O
block	O
of	O
code	O
to	O
be	O
used	O
as	O
a	O
program	O
on	O
its	O
own	O
,	O
or	O
compiled	B-Language
into	O
another	O
program	O
to	O
act	O
as	O
a	O
library	O
.	O
</s>
<s>
The	O
creation	O
of	O
code	O
as	O
a	O
program	O
or	O
subprogram	O
was	O
not	O
part	O
of	O
the	O
language	O
itself	O
,	O
handled	O
instead	O
by	O
placing	O
the	O
compiler	B-Language
directive	O
at	O
the	O
top	O
of	O
the	O
file	O
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
,	O
but	O
more	O
refined	O
and	O
narrower	O
scope	O
than	O
the	O
C-language	O
#include	O
mechanism	O
.	O
</s>
<s>
In	O
contrast	O
to	O
Pascal	B-Application
,	O
where	O
and	O
were	O
separate	O
concepts	O
,	O
SPL	B-Language
uses	O
a	O
more	O
C-like	B-Language
approach	O
where	O
any	O
can	O
be	O
prefixed	O
with	O
a	O
type	O
to	O
turn	O
it	O
into	O
a	O
function	O
.	O
</s>
<s>
In	O
keeping	O
with	O
the	O
syntax	O
of	O
other	O
ALGOL-like	B-Language
languages	O
,	O
the	O
types	O
of	O
the	O
parameters	O
were	O
listed	O
after	O
the	O
name	O
,	O
not	O
part	O
of	O
it	O
.	O
</s>
<s>
Although	O
frowned	O
upon	O
,	O
ALGOL	B-Language
and	O
Pascal	B-Application
allowed	O
code	O
to	O
be	O
labeled	O
using	O
a	O
leading	O
name	O
ending	O
with	O
a	O
colon	O
,	O
which	O
could	O
then	O
be	O
used	O
for	O
the	O
target	O
of	O
loops	O
and	O
statements	O
.	O
</s>
<s>
One	O
minor	O
difference	O
is	O
that	O
SPL	B-Language
required	O
the	O
label	O
names	O
to	O
be	O
declared	O
in	O
the	O
variable	O
section	O
using	O
the	O
keyword	O
.	O
</s>
<s>
SPL	B-Language
added	O
to	O
this	O
concept	O
with	O
the	O
statement	O
which	O
allowed	O
these	O
labels	O
to	O
be	O
further	O
defined	O
as	O
"	O
entry	O
points	O
"	O
that	O
could	O
be	O
accessed	O
from	O
the	O
command	O
line	O
.	O
</s>
<s>
Labels	O
named	O
in	O
the	O
entry	O
statement(s )	O
were	O
exposed	O
to	O
the	O
operating	B-General_Concept
system	I-General_Concept
and	O
could	O
be	O
called	O
from	O
the	O
RUN	O
command	O
.	O
</s>
<s>
Where	O
SPL	B-Language
differs	O
most	O
noticeably	O
from	O
ALGOL	B-Language
is	O
that	O
its	O
data	O
types	O
are	O
very	O
machine	O
specific	O
,	O
based	O
on	O
the	O
3000	O
's	O
16-bit	O
big	O
endian	O
word	O
format	O
.	O
</s>
<s>
There	O
is	O
no	O
equivalent	O
of	O
a	O
modifier	O
as	O
found	O
in	O
Pascal	B-Application
,	O
so	O
is	O
somewhat	O
wasteful	O
of	O
memory	O
when	O
used	O
only	O
to	O
store	O
a	O
single	O
binary	O
digit	O
,	O
although	O
SPL	B-Language
offers	O
bit	O
string	O
manipulation	O
as	O
an	O
alternative	O
.	O
</s>
<s>
Like	O
C	B-Language
,	O
data	O
is	O
weakly	O
typed	O
,	O
memory	O
locations	O
and	O
variable	O
storage	O
are	O
intermixed	O
concepts	O
,	O
and	O
one	O
can	O
access	O
values	O
directly	O
through	O
their	O
locations	O
.	O
</s>
<s>
defines	O
three	O
16-bit	O
integer	O
variables	O
,	O
A	O
,	O
B	O
and	O
C	B-Language
,	O
and	O
then	O
a	O
LOGICAL	O
,	O
also	O
a	O
16-bit	O
value	O
.	O
</s>
<s>
The	O
,	O
like	O
Pascal	B-Application
,	O
means	O
"	O
is	O
equivalent	O
to	O
"	O
,	O
not	O
"	O
gets	O
the	O
value	O
of	O
"	O
,	O
which	O
uses	O
in	O
Algol-like	B-Language
languages	O
.	O
</s>
<s>
So	O
the	O
second	O
line	O
states	O
"	O
declare	O
a	O
variable	O
D	O
that	O
is	O
in	O
the	O
same	O
memory	O
location	O
as	O
A+2	O
"	O
,	O
which	O
in	O
this	O
case	O
is	O
also	O
the	O
location	O
of	O
the	O
variable	O
C	B-Language
.	O
This	O
allows	O
the	O
same	O
value	O
to	O
be	O
read	O
as	O
an	O
integer	O
via	O
C	B-Language
or	O
a	O
logical	O
through	O
D	O
.	O
</s>
<s>
This	O
syntax	O
may	O
seem	O
odd	O
to	O
modern	O
readers	O
where	O
memory	O
is	O
generally	O
a	O
black	B-Device
box	I-Device
,	O
but	O
it	O
has	O
a	O
number	O
of	O
important	O
uses	O
in	O
systems	O
programming	O
where	O
particular	O
memory	O
locations	O
hold	O
values	O
from	O
the	O
underlying	O
hardware	O
.	O
</s>
<s>
Thus	O
declares	O
a	O
pointer	O
whose	O
value	O
contains	O
the	O
address	O
of	O
the	O
variable	O
A	O
,	O
not	O
the	O
value	O
of	O
A	O
.	O
can	O
be	O
used	O
on	O
either	O
side	O
of	O
the	O
assignment	O
;	O
puts	O
the	O
value	O
of	O
A	O
into	O
P	O
,	O
likely	O
resulting	O
in	O
a	O
dangling	B-Error_Name
pointer	I-Error_Name
,	O
makes	O
P	O
point	O
to	O
A	O
,	O
while	O
puts	O
the	O
value	O
of	O
A	O
into	O
the	O
location	O
currently	O
pointed	O
to	O
by	O
P	O
.	O
</s>
<s>
In	O
a	O
similar	O
fashion	O
,	O
SPL	B-Language
includes	O
C-like	B-Language
array	O
support	O
in	O
which	O
the	O
index	O
variable	O
is	O
a	O
number-of-words	O
offset	O
from	O
the	O
memory	O
location	O
set	O
for	O
the	O
initial	O
variable	O
.	O
</s>
<s>
Unlike	O
C	B-Language
,	O
SPL	B-Language
only	O
provided	O
one-dimensional	O
arrays	O
,	O
and	O
used	O
parentheses	O
as	O
opposed	O
to	O
brackets	O
.	O
</s>
<s>
This	O
mirrors	O
the	O
keyword	O
in	O
C	B-Language
.	O
</s>
<s>
Additionally	O
,	O
SPL	B-Language
had	O
a	O
keyword	O
that	O
allowed	O
a	O
string	O
of	O
text	O
to	O
be	O
defined	O
as	O
a	O
variable	O
,	O
and	O
then	O
replaced	O
any	O
instances	O
of	O
that	O
variable	O
in	O
the	O
code	O
with	O
the	O
literal	O
string	O
during	O
compiles	B-Language
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
the	O
keyword	O
in	O
C	B-Language
.	O
</s>
<s>
The	O
classic	O
HP	B-Device
3000	I-Device
organized	O
physical	O
memory	O
into	O
1	O
,	O
2	O
,	O
4	O
,	O
8	O
or	O
16	O
banks	O
of	O
64K	O
(	O
65536	O
)	O
16-bit	O
words	O
(	O
128K	O
bytes	O
)	O
.	O
</s>
<s>
Unlike	O
stacks	O
in	O
other	O
architectures	O
,	O
the	O
HP	B-Device
3000	I-Device
stack	O
was	O
used	O
for	O
process	O
globals	O
,	O
state	O
preservation	O
,	O
procedure	O
locals	O
(	O
supporting	O
nested	O
calls	O
and	O
re-entrancy	O
)	O
,	O
and	O
numeric	O
computation/evaluation	O
.	O
</s>
<s>
The	O
operating	B-General_Concept
system	I-General_Concept
provided	O
facilities	O
for	O
access	O
to	O
additional	O
memory-based	O
(	O
non-stack	O
)	O
data	O
segments	O
,	O
but	O
these	O
were	O
not	O
natively	O
addressed	O
by	O
the	O
instruction	O
set	O
and	O
so	O
the	O
program	O
was	O
responsible	O
for	O
moving	O
data	O
from	O
and	O
to	O
such	O
"	O
extra	O
data	O
segments	O
"	O
as	O
necessary	O
.	O
</s>
<s>
SPL	B-Language
included	O
a	O
variety	O
of	O
support	O
systems	O
to	O
allow	O
programs	O
to	O
be	O
easily	O
segmented	O
and	O
then	O
make	O
that	O
segmentation	O
relatively	O
invisible	O
in	O
the	O
code	O
.	O
</s>
<s>
The	O
primary	O
mechanism	O
was	O
to	O
use	O
the	O
compiler	B-Language
directive	O
which	O
defined	O
which	O
segment	O
the	O
following	O
code	O
should	O
be	O
placed	O
in	O
.	O
</s>
<s>
SPL	B-Language
included	O
a	O
"	O
bit-extraction	O
"	O
feature	O
that	O
allowed	O
simplified	O
bit	B-Algorithm
fiddling	I-Algorithm
.	O
</s>
<s>
(	O
Significantly	O
,	O
x	O
and	O
y	O
must	O
be	O
constants	O
known	O
at	O
compile	B-Language
time	O
.	O
)	O
</s>
<s>
This	O
simple	O
program	O
,	O
from	O
the	O
1984	O
version	O
of	O
the	O
reference	O
manual	O
,	O
shows	O
most	O
of	O
the	O
features	O
of	O
the	O
SPL	B-Language
language	O
.	O
</s>
<s>
It	O
begins	O
with	O
the	O
definition	O
of	O
a	O
series	O
of	O
global	O
variables	O
,	O
A	O
,	O
B	O
and	O
C	B-Language
,	O
defines	O
a	O
single	O
procedure	O
and	O
then	O
calls	O
it	O
twenty	O
times	O
.	O
</s>
<s>
INTEGER	O
A	O
:	O
=	O
0	O
,	O
B	O
,	O
C	B-Language
:	O
=	O
1	O
;	O
</s>
<s>
N(A,B,C )	O
;	O
</s>
