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APPENDIX F
8080/8085 PROCESSOR
DEPENDENCIES
Throughout
this
manual,
aspects
of
the
FORTRAN
language have been said
to
be
'processor
dependent'
or
'compiler
dependent.'
This appendix summarizes the
limitations
and
extensions to the
FORTRAN
language assumed by the 8080/8085
processors
and
compiler. See the
ISIS-II
FORTRAN-80
Compiler Operator's
Manual
for
details.
F.1
Processor Limitations
On
Language
Most limitations imposed
on
the
FORTRAN
language are related
to
data
lengths
and
the permissible range
of
data
values. The following indicates the range
of
values
possible for a given
data
length.
Length
INTEGER*1
INTEGER*2
INTEGER*4
LOGICAL*1
LOGICAL*2
LOGICAL*4
REAL
Value Range
-128
to
+ 127
- 32768
to
+ 32767
- 32768
to
+ 32767
.TRUE.
or
.FALSE.
.TRUE.
or
.FALSE.
.TRUE.
or
.FALSE.
Approximately
-3.37E+38
to
+3.37E+38.
The
handling
of
magnitudes less
than
1.17E -
38
is
not
defined.
If
no length
is
specified, the compiler defaults are
INTEGER
*2
and
LOGICAL
*
1.
The maximum field width,
'w,'
in the
Fw.d,
Ew.d,
Iw,
and
Lw edit descriptors
of
the
FORMAT
statement
is
32,767.
The
length
and
interpretation
of
integer expression values
is
determined as follows:
• Addition, subtraction, multiplication, division,
or
exponentation
is
performed
modulo
256 for two
INTEGER
* 1 operands
and
modulo
65536 otherwise.
• Assignment
is
performed
modulo
256
if
the variable whose value
is
being
assigned has type
INTEGER
* 1
and
modulo
65536 otherwise.
• The length
of
the value
of
integer expressions used as actual arguments
(but
which are
not
variables
or
array
elements)
is
at
least the default length
of
an
in-
teger variable.
• Subscript expression values are
taken
modulo
2**16.
In
all
of
the cases listed above, overflow is ignored.
F.2 Compiler Extensions
The
ISIS-II
FORTRAN-80
compiler provides a
number
of
features in addition
to
those defined as
part
of
the
FORTRAN
language. Some
of
these features are provid-
ed by 'compiler
controls.'
This appendix mentions only those compiler controls
that
affect interpretation
of
FORTRAN
source code. Controls affecting compiler
output
are
not
included here,
but
can be
found
in the compiler
operator's
manual.
F-l