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Calling Non-BASIC-SO Subroutines
E-4
Some Real Examples
The three sample programs provided in Figures E-2, E-3, and E-4 show how the
same
subroutine-
adding three integer
arguments-can
be coded in FORTRAN-SO,
PL/M-SO,
and
SOSO/SOS5
assembly language. Notice
that
each program requires
three parameters.
Once you have processed your subroutine through the PL/M-SO
or
FORTRAN-SO
compilers,
or
through the
SOSO/SOS5
assembler, you can convert it to absolute
object code and place it in memory with the
LOCATE command. You must give the
filename
of
your relocatable code file and the proper starting address for the
subroutine code. In the example below ,
LOCATE returns absolute object code
whose first byte
is
at
address
OEOOOH:
-LOCATE
:F1
:PLMSUB.OBJ
CODE
(OEOOOH)
This command returns the absolute object file :Fl:PLMSUB. You can now load this
located code into Intellec memory
at
its proper address with the monitor DEBUG
command. When you enter the DEBUG command with your filename, you invoke
the Monitor, as shown in the example below. The Monitor responds with a period
(.), expecting further commands:
-DEBUG:F1
:PLMSUB
#0000
You can now return to ISIS-II and test your subroutine. Leave the Monitor and
return to
ISIS-II by entering
GS
and a carriage return after the period:
.G8 (CR)
ISIS-II Vm.n
Invoke BASIC-SO, and specify the highest memory address
BASIC-SO
can use with
the
MEMTOP option:
-:F1
:BASIC MEMTOP(ODFFFH)
This prevents BASIC-SO from writing over your subroutine.
BASIC-SO
will appear
and tell you how much free memory you have left:
ISIS-II BASIC-80 V1.0
18157
BYTES FREE
Once in
BASIC-SO
you can write programs that use your subroutine. The following
BASIC-SO program defines your subroutine as
USRl,
asks for three integers, passes
these three integer values to the subroutine, defines the result
of
the subroutine as
the variable
RESULT,
and
finally prints RESULT:
10
REM THIS PROGRAM ASKS
FOR
THREE
20
REM INTEGERS, PASSES THEM TO USR1, AND
30
REM RETURNS THE RESULT.
40
DEFINT A-Z
50
DEFUSR
1=OEOOOH
60
PRINT"ENTER THREE
NUMBERS:"
70
INPUT
A,B,C
80
PRINT"
A="
,A,
"B="
,B,
"C="
,C
90
RESULT=USR%1(VARPTR(A), VARPTR(B), VARPTR(C»)
100
PRINT"A+B+C=";
RESULT
110
END
BASIC-80