Intel fortran-80 Appendix F 8080/8085 Processor Dependencies, Processor Limitations On Language

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-IIFORTRAN-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	Value Range
INTEGER*1	-128 to + 127
INTEGER*2	- 32768 to + 32767
INTEGER*4	- 32768 to + 32767
LOGICAL*1	.TRUE. or .FALSE.
LOGICAL*2	.TRUE. or .FALSE.
LOGICAL*4	.TRUE. or .FALSE.
REAL	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.

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