On ... Gosub, On ... Goto, Open | Intel 9800758-02 guide

Commands and Statements

BASIC-SO

ON ... GOSUB

The ON ... GOSUB statement transfers program control to one or one of a set of subroutines.The line numbers of the first lines of these subroutines follow sequen- tially, separated by commas. If the expression evaluates to 3, control transfers to the third line number following GOSUB.

ON expression GOSUB line number [,Iine number] ...

10 INPUT A

20 ON A GOSUB 200,300

ON ... GOTO

The ON ... GOTO statement transfers program control to one or one of a set of line numbers. The expression X is evaluated and control is transferred to the "nth" line number following the line containing the ON ...GOTO instruction. If the expression evaluates to 3, control transfers to the third line number following GOSUB.

ON expression GOTO line number [,Iine number] ...

10 INPUT A

20 ON A GOTO 500,510,520

OPEN

The OPEN statement makes an ISIS-II file available to BASIC. It also associates a file number from 1 to 6 with the file. File type can be I, 0, or R. Random 110 files are specified by an R, sequential input files are specified by an I, and sequential output files are specified by an 0, as shown in the syn- tactic format below. The file number is an integer expression greater than 0 and less than or equal to 6, is preceded by a "#" sign, and is used to reference the file in 110 transactions.

Only six files may be open at one time. Note that SAVE, LOAD, DSKF; DIR and MERGE all require a file, so a maximum of five files may be open before they are executed.

BASIC-SO buffers files, so if :CI: is opened for input, BASIC-SO will wait for the first line of console input.

OPEN type, [I] file number, filename

where type is a string expression equal to "0", "I" or "R". In the example below, the file SYSLIB is opened as a random I/O file, with number 4.

OPEN "R" ,#4, "SYSLlB"

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Intel 9800758-02 manual On ... Gosub, On ... Goto, Open

Contents

BASIC-SO Reference Manual A108/0979/7500 FL Preface Page Contents Illustrations Chapter Introduction to BASIC-80 Invoking BASIC-80 Basic filename MEMTOPaddress ExamplesIntroduction to BASIC-80 Filename Changing File Attributes Listing the Directory of a DiskRenaming a File Deleting a File You can now run, list, or edit the program Save LP ,A Commands Statements BASIC-80 Commands Contd BASIC-80 Statements BASIC-80 Statements Contd BASIC-80 Functions BASIC-80 Functions Contd Representing Data Functions Decimal Integer Constants ConstantsInteger Constants Hexadecimal Integer Constants Octal Integer Constants Single-Precision Floating-Point ConstantsDouble-Precision Floating-Point Constants This is a string constant String ConstantsString Variables $ = Enter next data string L4! = Csng l4 YI,1 String Arrays Arithmetic Operators BASIC-SO Operators in Order of Precedence Contd Numeric Expressions Logical OperatorsString Operator String Expressions Entering and Editing Programs 30 A=8*52 30 A=8*37 30 A=8*5230 A=8 30 A--=8xx*522537 Control-R a = 8*37 Integer D SubcommandCommand 3D press 3, then D results If AB then If AB then 120 Else Null SET Syntax of the X subcommand is At this point, the other editing subcommands may be used Move the cursor to PRINT. Enter 2C RE L Print Undefined SET The E subcommand is enteredInteger C character character Print Undefined SET. Enter a L BASIC-80 Error Messages Syntax Error MessagesOverflow, Underflow, and Divide-by-Zero Error Trapping Trace Facility Restarting Program Execution Error SimulationError Handling If line 40 is replaced with Opening a Sequential File Open 1,#1,F1DATES Reading from a Sequential File Refer to for further details of Print UsingWriting to a Sequential File If executed four times, it would read all eight values Closing a Sequential File Value of R$ would be Buffers Defining a Random 1/0 Field-FIELDField #3, 20 AS N$ Disk File Input/Output Field #3, 20 AS N$, 9 AS SS$ Any of the parameters can be variables Opening and Closing a Random Disk FileReading from a Random 1/0 File To read the next record Single-precision value Writing to a Random 1/0 FileInteger Double-precision value MKI$ Auto first lineJ, increment Attrib Fdrive numberfilename, W1Attrib Fdrive numberfilename, WO Clear expression,address Commands and Statements Close DEF FNX Rules for function name are the same as for variable name Defsng Defdbl Defstr Defint DIM Delete Edit ErrorDIR END Field Error expressionExit FOR-NEXT-STEP For variable=expression to expression Step expression GETGosub GET I file number ,record number IF-THEN-ELSE InputGoto Line Input KillLET List LSET, Rset Load Merge NEW Next 9 16 On ... Gosub On ... GotoOpen Option Base OUTPoke Print Using PrintString Fields Numeric fields If X$=SEVEN and Y$=EIGHT, the results of line 40 would be Prun PUT Randomize Read REM Resume Return Line number RUN filename SaveRUN line numberlstring expression ,F 60 END TRON, Troff ? 5,8,2 Wait Width ABS ATN CHR$ CintFunctions 10 A# = 1.00/3.00 CsngCVI CVS AO/o = Dskf EOF FIX Ok· Hexs INPInputs INT InstrLEFT$ LOF LENLOC LOG MID$ MKI$ MKS$ MKD$OCT$ POS integer RightsPeek expression RIGHT$ string,integer Spaces SGNSIN 10 a =1 If A$ = 2 then Print Correct Else Goto SPCSPC integer SQRexpression STR$ expression TAB expressionTAN expression Here is an example of how the USRn statement is used 60 AO/o = Appendix a BASIC-SO Error Codes Table A-I. BASIC-80 Error Codes Table A-I. BASIC-SO Error Codes Contd Appendix B BASIC-SO Reserved Words Page To tab across the line To halt program execution and return to commandLevel To resume program execution after it is stopped byPage Table D-l. Ascii Code List Appendix D Ascii Codes Table D-2. Ascii Code Definition BEL Appendixe Calling Subroutines Figure B-1. Internal Representation of Numbers and Strings Some Real Examples RESULT=USR%1VARPTRA, VARPTRB, VARPTRC» PRINTA+B+C= Result Figure E-2 /8085 Assembly Language Program Figure E-3. PL/M-80 Program Appendix F RMX/SO BASIC-SO Initializing the Predefined RMX/SO BASIC-SO Configuration ISIS-II BASIC-SO Table F-l. Sample Configuration Jumper Wiring OOOOH-OFFFH BASIC-80 Object Files Generating Boot-Loaded and PROM-Based VersionsBASIC-80 Source Files BASIC-80 Executable Files Generating a Boot-Loaded RMX/80 BASIC-80 Setting baud rates, refer to the RMX/SO Users Guide That are not boot loadedThis option is used to allocate memory. It is 1 if the boot This option enables your user-written I/O drivers if you ISBC 80/20-4 Generating a PROM-Based RMX/80 BASIC-80 Prom F1 RMX820.L1BSTART, & FOBASCM.OBJ,& FORMXBAS.LlB F1 DFSDIR. L1BDIRECTORY ,RENAM E,& F1 MTI810.L1B Configuration Requirements Configuring DFS on an iSBC 80/10Adding BASIC-SO to an Existing RMX/SO Configuration ISBC SO/10 System Clock Public Variables Adding User-Written I/O Drivers to RMX/SO BASIC-SO Open 0,#1, L1LlST Figure F-S. Sample User-Written 1/0 Driver Routine Altering BASIC-80 Workspace Burning a BASIC-80 Program Into Prom Baprom F1HEATER.BAS Page Index Ase BASIC-80 RIGHT$,7-1O Request for Readerscomments 111111