<s>
WATFIV	B-Language
,	O
or	O
WATerloo	O
FORTRAN	B-Application
IV	O
,	O
developed	O
at	O
the	O
University	O
of	O
Waterloo	O
,	O
Canada	O
is	O
an	O
implementation	O
of	O
the	O
Fortran	B-Application
computer	O
programming	O
language	O
.	O
</s>
<s>
It	O
is	O
the	O
successor	O
of	O
WATFOR	B-Language
.	O
</s>
<s>
WATFIV	B-Language
was	O
used	O
from	O
the	O
late	O
1960s	O
into	O
the	O
mid-1980s	O
.	O
</s>
<s>
WATFIV	B-Language
was	O
in	O
turn	O
succeeded	O
by	O
later	O
versions	O
of	O
WATFOR	B-Language
.	O
</s>
<s>
Because	O
it	O
could	O
complete	O
the	O
three	O
usual	O
steps	O
(	O
"	O
compile-link-go	O
"	O
)	O
in	O
just	O
one	O
pass	O
,	O
the	O
system	O
became	O
popular	O
for	O
teaching	O
students	O
computer	O
programming	O
.	O
</s>
<s>
In	O
the	O
early	O
1960s	O
,	O
newly	O
formed	O
computer	B-General_Concept
science	I-General_Concept
departments	O
started	O
university	O
programs	O
to	O
teach	O
computer	O
programming	O
languages	O
.	O
</s>
<s>
The	O
Fortran	B-Application
language	I-Application
had	O
been	O
developed	O
at	O
IBM	O
,	O
but	O
suffered	O
from	O
slow	O
and	O
error-prone	O
three-stage	O
batch	B-General_Concept
processing	I-General_Concept
workflow	O
.	O
</s>
<s>
In	O
the	O
first	O
stage	O
,	O
the	O
compiler	B-Language
started	O
with	O
source	O
code	O
and	O
produced	O
object	B-Application
code	I-Application
.	O
</s>
<s>
In	O
the	O
second	O
stage	O
,	O
a	O
linker	B-Application
constructed	O
a	O
complete	O
program	O
using	O
growing	O
libraries	O
of	O
common	O
functions	O
.	O
</s>
<s>
Each	O
step	O
often	O
included	O
a	O
new	O
set	O
of	O
punched	B-Architecture
cards	I-Architecture
or	O
tape	O
.	O
</s>
<s>
Their	O
programs	O
were	O
generally	O
short	O
,	O
but	O
usually	O
contained	O
logic	O
and	O
syntax	O
errors	O
,	O
resulting	O
in	O
time-consuming	O
repetition	O
of	O
the	O
steps	O
and	O
confusing	O
"	O
core	B-Error_Name
dumps	I-Error_Name
"	O
(	O
It	O
often	O
took	O
a	O
full	O
day	O
to	O
submit	O
and	O
receive	O
the	O
successful	O
or	O
failed	O
output	O
from	O
the	O
computer	O
operator	O
)	O
.	O
</s>
<s>
In	O
1961	O
,	O
the	O
University	O
of	O
Wisconsin	O
developed	O
a	O
technology	O
called	O
FORGO	O
for	O
the	O
IBM	B-Device
1620	I-Device
which	O
combined	O
some	O
of	O
the	O
steps	O
.	O
</s>
<s>
Similar	O
experiments	O
were	O
carried	O
out	O
at	O
Purdue	O
University	O
on	O
the	O
IBM	B-Device
7090	I-Device
in	O
a	O
system	O
called	O
PUFFT	O
.	O
</s>
<s>
Richard	O
Shirley	O
and	O
Robert	O
Zarnke	O
,	O
led	O
by	O
Peter	O
Shantz	O
,	O
developed	O
a	O
Fortran	B-Application
compiler	B-Language
for	O
the	O
IBM	B-Device
7040	I-Device
computer	O
called	O
WATFOR	B-Language
.	O
</s>
<s>
Its	O
objectives	O
were	O
fast	O
compilation	B-Language
speed	O
and	O
effective	O
error	O
diagnostics	O
at	O
both	O
compile	B-Language
and	O
execution	O
time	O
.	O
</s>
<s>
It	O
eliminates	O
the	O
need	O
for	O
a	O
separate	O
linking	B-Application
step	O
and	O
,	O
as	O
a	O
result	O
,	O
FORTRAN	B-Application
programs	O
which	O
contain	O
no	O
syntax	O
errors	O
are	O
placed	O
into	O
immediate	O
execution	O
.	O
</s>
<s>
To	O
aid	O
in	O
debugging	O
,	O
the	O
compiler	B-Language
uses	O
an	O
innovative	O
approach	O
to	O
checking	O
for	O
undefined	O
variables	O
(	O
an	O
extremely	O
common	O
mistake	O
by	O
novice	O
programmers	O
)	O
.	O
</s>
<s>
When	O
a	O
program	O
tries	O
to	O
reference	O
variables	O
that	O
had	O
n't	O
been	O
set	O
,	O
the	O
machine	O
takes	O
an	O
interrupt	O
(	O
handled	O
by	O
the	O
Watfor	B-Language
runtime	O
routines	O
)	O
and	O
the	O
error	O
is	O
reported	O
to	O
the	O
user	O
as	O
an	O
undefined	O
variable	O
.	O
</s>
<s>
WATFOR	B-Language
quickly	O
gained	O
popularity	O
and	O
over	O
75	O
institutions	O
installed	O
it	O
on	O
their	O
IBM	B-Device
7040	I-Device
systems	O
.	O
</s>
<s>
The	O
distribution	O
of	O
the	O
compiler	B-Language
was	O
handled	O
by	O
Sandra	O
Bruce	O
(	O
née	O
Hope	O
)	O
.	O
</s>
<s>
In	O
1966	O
,	O
the	O
University	O
planned	O
to	O
replace	O
the	O
7040	O
with	O
an	O
IBM	B-Application
System/360	I-Application
computer	O
,	O
which	O
was	O
much	O
faster	O
but	O
not	O
software	O
compatible	O
.	O
</s>
<s>
A	O
team	O
of	O
full-time	O
employees	O
and	O
undergraduate	O
students	O
was	O
formed	O
to	O
write	O
an	O
IBM	B-Application
360	I-Application
version	O
.	O
</s>
<s>
The	O
project	O
members	O
,	O
Betty	O
Schmidt	O
,	O
Paul	O
Dirksen	O
,	O
Paul	O
H	O
.	O
Cress	O
,	O
Lothar	O
K	O
.	O
"	O
Ned	O
"	O
Kesselhut	O
,	O
Bill	O
Kindree	O
and	O
Dereck	O
Meek	O
,	O
were	O
later	O
joined	O
by	O
Mike	O
Doyle	O
,	O
Rod	O
Milne	O
,	O
Ron	O
Hurdal	O
and	O
Lynn	O
Williams	O
,	O
completed	O
360	O
WATFOR	B-Language
in	O
the	O
early	O
part	O
of	O
1967	O
.	O
</s>
<s>
Many	O
other	O
institutions	O
(	O
universities	O
,	O
colleges	O
,	O
businesses	O
and	O
governmental	O
agencies	O
)	O
started	O
using	O
the	O
WATFOR	B-Language
compiler	B-Language
to	O
meet	O
needs	O
similar	O
to	O
those	O
experienced	O
at	O
the	O
University	O
of	O
Waterloo	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
proposals	O
from	O
the	O
SHARE	O
user	O
group	O
Fortran	B-Application
committee	O
and	O
others	O
,	O
a	O
new	O
version	O
called	O
WATFIV	B-Language
was	O
produced	O
in	O
1968	O
.	O
</s>
<s>
WATFIV	B-Language
introduced	O
new	O
features	O
such	O
as	O
CHARACTER	O
variables	O
and	O
direct-access	O
input-output	O
.	O
</s>
<s>
The	O
Association	O
for	O
Computing	O
Machinery	O
presented	O
Paul	O
Cress	O
and	O
Paul	O
Dirksen	O
the	O
Grace	O
Murray	O
Hopper	O
Award	O
for	O
contributions	O
to	O
the	O
WATFOR	B-Language
and	O
WATFIV	B-Language
projects	O
in	O
1972	O
.	O
</s>
<s>
The	O
WATFIV	B-Language
compiler	B-Language
was	O
included	O
in	O
the	O
DATAPRO	O
Honour	O
Roll	O
for	O
1975	O
and	O
1976	O
.	O
</s>
<s>
WATFIV	B-Language
was	O
pronounced	O
as	O
"	O
WHAT	O
FIVE	O
"	O
,	O
but	O
,	O
as	O
was	O
realized	O
at	O
the	O
time	O
,	O
could	O
also	O
(	O
almost	O
)	O
still	O
be	O
pronounced	O
as	O
"	O
WHAT	O
FOR	O
"	O
,	O
as	O
in	O
WAT-F-IV	O
(	O
Waterloo	O
Fortran	B-Application
IV	O
)	O
.	O
</s>
<s>
Universities	O
and	O
corporations	O
used	O
these	O
compilers	B-Language
and	O
a	O
number	O
of	O
other	O
software	O
products	O
have	O
been	O
developed	O
in	O
the	O
WATFOR	B-Language
tradition	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
version	O
for	O
the	O
COBOL	B-Application
programming	I-Application
language	I-Application
is	O
called	O
WATBOL	B-Application
.	O
</s>
<s>
Daniel	O
D	O
.	O
McCracken	O
said	O
"	O
it	O
is	O
no	O
exaggeration	O
to	O
suggest	O
that	O
WATFOR	B-Language
revolutionized	O
the	O
use	O
of	O
computers	O
in	O
education.	O
"	O
</s>
<s>
In	O
1974	O
,	O
a	O
compiler	B-Language
with	O
characteristics	O
similar	O
to	O
the	O
IBM	O
implementation	O
was	O
created	O
for	O
the	O
Digital	O
Equipment	O
Corporation	O
PDP-11	B-Device
computer	O
and	O
called	O
WATFOR-11	O
.	O
</s>
<s>
The	O
team	O
members	O
,	O
Jack	O
Schueler	O
,	O
Jim	O
Welch	O
and	O
Terry	O
Wilkinson	O
,	O
were	O
later	O
joined	O
by	O
Ian	O
McPhee	O
who	O
had	O
added	O
new	O
control	O
statements	O
to	O
the	O
WATFIV	B-Language
compiler	B-Language
for	O
structured	B-Language
programming	I-Language
(	O
SP	O
)	O
.	O
</s>
<s>
WATFIV-S	O
was	O
announced	O
in	O
1974	O
and	O
a	O
few	O
months	O
later	O
,	O
WATFOR-11S	O
(	O
the	O
"	O
S	O
"	O
indicating	O
the	O
new	O
SP	O
features	O
)	O
was	O
also	O
announced	O
.	O
</s>
<s>
The	O
original	O
SP	O
features	O
were	O
later	O
enhanced	O
with	O
additional	O
statements	O
by	O
Bruce	O
Hay	O
in	O
WATFIV-S	O
in	O
1980	O
and	O
by	O
Jack	O
Schueler	O
in	O
WATFOR-11S	O
in	O
1981	O
.	O
</s>
<s>
During	O
the	O
1970s	O
,	O
the	O
ANSI	O
X3J3	B-Application
subcommittee	O
(	O
the	O
FORTRAN	B-Application
language	I-Application
standard	O
group	O
)	O
developed	O
a	O
new	O
language	O
standard	O
which	O
was	O
officially	O
approved	O
in	O
April	O
,	O
1978	O
.	O
</s>
<s>
This	O
standard	O
,	O
designated	O
FORTRAN	B-Application
77	O
,	O
introduced	O
many	O
new	O
statements	O
into	O
the	O
language	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	O
previous	O
language	O
standard	O
FORTRAN	B-Application
66	O
is	O
a	O
very	O
small	O
document	O
and	O
describes	O
,	O
what	O
is	O
in	O
effect	O
,	O
a	O
subset	O
of	O
most	O
implementations	O
of	O
FORTRAN	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
the	O
WATFIV	B-Language
and	O
WATFOR-11	O
implementations	O
are	O
based	O
upon	O
the	O
IBM	O
definition	O
of	O
FORTRAN-IV	O
.	O
</s>
<s>
As	O
programmers	O
used	O
the	O
FORTRAN	B-Application
77	O
features	O
,	O
a	O
new	O
compiler	B-Language
was	O
required	O
to	O
combine	O
the	O
advantages	O
of	O
the	O
WATFIV	B-Language
compiler	B-Language
with	O
the	O
new	O
language	O
standard	O
.	O
</s>
<s>
In	O
January	O
1983	O
,	O
a	O
project	O
to	O
develop	O
a	O
FORTRAN	B-Application
77	O
compiler	B-Language
was	O
started	O
at	O
Watcom	O
Systems	O
Inc	O
.	O
</s>
<s>
Under	O
the	O
leadership	O
of	O
Jack	O
Schueler	O
,	O
Watcom	O
employees	O
and	O
undergraduate	O
students	O
from	O
the	O
University	O
of	O
Waterloo	O
's	O
Co-operative	O
Computer	B-General_Concept
Science	I-General_Concept
program	O
became	O
involved	O
in	O
the	O
creation	O
of	O
the	O
WATFOR-77	O
compiler	B-Language
.	O
</s>
<s>
Many	O
of	O
the	O
team	O
members	O
from	O
former	O
compiler	B-Language
projects	O
provided	O
input	O
.	O
</s>
<s>
Unlike	O
previous	O
compilers	B-Language
,	O
a	O
significant	O
portion	O
of	O
WATFOR-77	O
was	O
written	O
in	O
a	O
portable	O
systems	O
language	O
to	O
ease	O
the	O
implementation	O
of	O
the	O
compiler	B-Language
on	O
other	O
computer	O
systems	O
.	O
</s>
<s>
Earlier	O
WATFOR	B-Language
compilers	B-Language
were	O
written	O
entirely	O
in	O
machine-dependent	O
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Two	O
components	O
of	O
the	O
compiler	B-Language
are	O
not	O
portable	O
.	O
</s>
<s>
The	O
code	O
generator	O
translates	O
FORTRAN	B-Application
statements	O
into	O
native	O
computer	O
instructions	O
and	O
stores	O
them	O
in	O
memory	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
WATFOR-77	O
generates	O
instructions	O
for	O
the	O
IBM	O
370	O
computer	O
architecture	O
.	O
</s>
<s>
Most	O
of	O
the	O
execution-time	O
support	O
(	O
undefined	O
variable	O
checking	O
,	O
subscript	O
evaluation	O
,	O
intrinsic	O
functions	O
)	O
was	O
written	O
in	O
assembly	B-Language
language	I-Language
for	O
good	O
performance	O
.	O
</s>
<s>
It	O
was	O
an	O
implementation	O
for	O
IBM	O
370	O
computers	O
running	O
the	O
VM/SP	B-Application
CMS	I-Application
operating	O
system	O
.	O
</s>
<s>
A	O
few	O
months	O
earlier	O
,	O
in	O
May	O
1984	O
,	O
a	O
project	O
started	O
to	O
implement	O
the	O
WATFOR-77	O
compiler	B-Language
on	O
the	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
.	O
</s>
<s>
In	O
April	O
1985	O
,	O
this	O
second	O
version	O
of	O
WATFOR-77	O
was	O
installed	O
at	O
the	O
University	O
of	O
Waterloo	O
for	O
use	O
by	O
students	O
of	O
the	O
Faculty	O
of	O
Engineering	O
.	O
</s>
<s>
The	O
compiler	B-Language
can	O
run	O
on	O
a	O
256K	O
IBM	B-Device
Personal	I-Device
Computer	I-Device
using	O
IBM	B-Device
PC	I-Device
DOS	O
2.0	O
and	O
does	O
not	O
require	O
special	O
floating-point	O
hardware	O
.	O
</s>
<s>
In	O
the	O
fall	O
of	O
1985	O
,	O
a	O
Japanese	O
version	O
of	O
WATFOR-77	O
was	O
delivered	O
to	O
IBM	O
Japan	O
for	O
the	O
IBM	B-Device
JX	I-Device
Personal	I-Device
Computer	I-Device
.	O
</s>
<s>
Another	O
version	O
of	O
WATFOR-77	O
with	O
the	O
same	O
features	O
mentioned	O
above	O
was	O
also	O
developed	O
for	O
Japanese	O
IBM	O
PS/55	O
family	O
of	O
personal	O
computers	O
in	O
Spring	O
1988	O
.	O
</s>
<s>
During	O
the	O
summer	O
of	O
1986	O
,	O
the	O
IBM	B-Device
PC	I-Device
version	O
of	O
WATFOR-77	O
was	O
adapted	O
to	O
run	O
on	O
the	O
Unisys	B-Device
ICON	I-Device
which	O
runs	O
the	O
QNX	B-Operating_System
operating	O
system	O
.	O
</s>
<s>
Since	O
QNX	B-Operating_System
is	O
quite	O
different	O
from	O
IBM	B-Device
PC	I-Device
DOS	O
,	O
parts	O
of	O
the	O
run-time	O
system	O
were	O
rewritten	O
.	O
</s>
<s>
This	O
implementation	O
of	O
WATFOR-77	O
was	O
made	O
available	O
in	O
September	O
1986	O
.	O
</s>
<s>
During	O
the	O
summer	O
of	O
1985	O
,	O
a	O
project	O
was	O
started	O
to	O
adapt	O
WATFOR-77	O
to	O
the	O
Digital	O
Equipment	O
Corporation	O
VAX	B-Device
computer	O
series	O
running	O
the	O
VMS	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
.	O
</s>
<s>
Also	O
,	O
in	O
the	O
spring	O
of	O
1988	O
,	O
a	O
new	O
project	O
was	O
begun	O
to	O
develop	O
an	O
optimizing	O
FORTRAN	B-Application
77	O
compiler	B-Language
.	O
</s>
<s>
This	O
compiler	B-Language
uses	O
the	O
code	O
generator	O
from	O
the	O
Watcom	B-Application
C	I-Application
compiler	I-Application
,	O
which	O
produces	O
superior	O
machine	O
code	O
to	O
other	O
C	O
compilers	B-Language
.	O
</s>
<s>
The	O
FORTRAN	B-Application
77	O
optimizing	O
compiler	B-Language
was	O
first	O
shipped	O
in	O
mid-1990	O
.	O
</s>
<s>
In	O
October	O
1990	O
,	O
the	O
25th	O
anniversary	O
of	O
WATFOR	B-Language
was	O
celebrated	O
.	O
</s>
<s>
Many	O
involved	O
in	O
the	O
development	O
of	O
the	O
WATFOR	B-Language
compilers	B-Language
were	O
invited	O
to	O
the	O
University	O
of	O
Waterloo	O
for	O
a	O
reunion	O
.	O
</s>
<s>
In	O
spring	O
1992	O
,	O
a	O
version	O
of	O
WATFOR-77	O
was	O
adapted	O
to	O
the	O
NEC	B-Operating_System
PC-9801	I-Operating_System
family	O
of	O
personal	O
computers	O
.	O
</s>
<s>
In	O
January	O
1992	O
,	O
development	O
of	O
a	O
32-bit	O
version	O
of	O
WATFOR-77	O
for	O
Intel	B-General_Concept
80386	I-General_Concept
and	O
Intel	B-General_Concept
80486	I-General_Concept
personal	O
computers	O
began	O
.	O
</s>
<s>
As	O
late	O
as	O
1995	O
,	O
classes	O
for	O
programming	O
in	O
WATFIV	B-Language
were	O
still	O
being	O
held	O
at	O
the	O
University	O
of	O
Mississippi	O
,	O
led	O
by	O
Professor	O
Charles	O
H	O
.	O
(	O
Chuckie	O
)	O
Franke	O
.	O
</s>
