<s>
massively	B-Operating_System
parallel	I-Operating_System
computer	I-Operating_System
.	O
</s>
<s>
Their	O
manager	O
and	O
a	O
major	O
contributor	O
was	O
John	O
K	O
Iliffe	O
who	O
had	O
designed	O
the	O
Basic	O
Language	O
Machine	O
—	O
he	O
is	O
well	O
known	O
nowadays	O
for	O
Iliffe	B-Data_Structure
vectors	I-Data_Structure
.	O
</s>
<s>
The	O
ICL	B-Device
DAP	I-Device
had	O
64×64	O
single	O
bit	O
processing	O
elements	O
(	O
PEs	O
)	O
with	O
4096	O
bits	O
of	O
storage	O
per	O
PE	O
.	O
</s>
<s>
Programs	O
for	O
the	O
DAP	O
were	O
written	O
in	O
DAP	B-General_Concept
FORTRAN	I-General_Concept
which	O
was	O
FORTRAN	B-Application
extended	O
with	O
64×64	O
matrix	O
and	O
64	O
element	O
vector	O
primitives	O
.	O
</s>
<s>
DAP	B-General_Concept
Fortran	I-General_Concept
compiled	O
to	O
an	O
assembly	B-Language
language	I-Language
called	O
APAL	O
(	O
Array	O
Processor	O
Assembly	B-Language
Language	I-Language
)	O
.	O
</s>
<s>
The	O
DAP	O
had	O
a	O
Single	B-Device
Instruction	I-Device
Multiple	I-Device
Data	I-Device
(	O
SIMD	B-Device
)	O
architecture	O
.	O
</s>
<s>
Array	O
programs	O
were	O
executed	O
as	O
subroutines	O
of	O
normal	O
mainframe	O
FORTRAN	B-Application
programs	O
and	O
IO	O
was	O
handled	O
by	O
the	O
mainframe	O
.	O
</s>
<s>
The	O
ICL	B-Device
2980	I-Device
was	O
not	O
a	O
popular	O
machine	O
and	O
this	O
held	O
back	O
the	O
use	O
of	O
the	O
DAP	O
as	O
an	O
attached	O
processor	O
was	O
restricted	O
initially	O
to	O
this	O
one	O
range	O
.	O
</s>
<s>
It	O
could	O
be	O
programmed	O
in	O
either	O
C++	B-Language
or	O
Fortran-Plus	O
.	O
</s>
<s>
These	O
were	O
more	O
flexible	O
than	O
DAP	B-General_Concept
FORTRAN	I-General_Concept
,	O
in	O
particular	O
they	O
automatically	O
took	O
care	O
of	O
choosing	O
a	O
mapping	O
from	O
user	O
specified	O
matrix	O
and	O
vector	O
bounds	O
to	O
the	O
underlying	O
hardware	O
.	O
</s>
<s>
The	O
commercial	O
version	O
was	O
called	O
the	O
Mini-DAP	O
,	O
normally	O
attached	O
to	O
a	O
PERQ	B-Device
system	O
(	O
so	O
was	O
sometimes	O
called	O
the	O
PERQ-DAP	O
)	O
,	O
and	O
the	O
ruggedised	O
military	O
version	O
was	O
called	O
the	O
Mil-DAP	O
.	O
</s>
