Intel 9800758-02 manual Opening a Sequential File, Open 1,#1,F1DATES

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CHAPTER 5

DISK FILE INPUT/OUTPUT

BASIC-SO includes two types of disk file Input/Output operations: sequential and random. Sequential I/O lets you read or write a file from the beginning to the end; random I/O lets you specify where in the file you read or write.

Because BASIC-SO runs under ISIS-II and RMX/SO, filenames correspond to the ISIS-II and RMX/80-DFS format (:Fn:name.ext, where n is the drive number). BASIC-SO also gives you access to disk file-handling commands:

•DIR, which lists the files on a disk

•RENAME, which changes the name of a disk file

•ATTRIB, which changes the attributes of a disk file

•KILL, which deletes a disk file (it is actually the system DELETE command, but the name must be different because BASIC-SO includes a DELETE command to delete lines from a program).

For more information about ISIS-II filenames or operations, see the ISIS-II User's

Guide.

Although both sequential and random I/O allow you to create, read, and write files on disk, sequential I/O is somewhat simpler in concepts and operation. If you haven't worked with disk files before, it would probably be better to start with se- quential 110 to learn the principles.

Sequential File 1/0

BASIC-SO Sequential I/O allows you to build sequential data files containing numbers and strings of up to 255 characters. In general, to use sequential 110 you must open the file, execute a series of INPUT (to read) or PRINT (to write) statements, then close the file.

A sequential file is open either for input or output. To switch from one to the other, you must close the file and open it again with the opposite attribute. Any 110 opera- tion that immediately follows an OPEN statement starts at the beginning of the file.

Opening a Sequential File

You open a sequential file with the OPEN statement. It specifies whether the file is to be opened for input or output, assigns it a file number, and specifies the filename. Up to six files can be open at one time. If the file named in an OPEN statement that specifies output does not exist, it is created. Once a file is open, it cannot be opened again without closing it first. If you attempt to do so, an error message results.

To open an input file named :Fl:DATES and assign it file number 1:

OPEN "1",#1,":F1:DATES"

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Contents BASIC-SO Reference Manual A108/0979/7500 FL Preface Page Contents Illustrations Invoking BASIC-80 Chapter Introduction to BASIC-80Introduction to BASIC-80 ExamplesBasic filename MEMTOPaddress FilenameRenaming a File Listing the Directory of a DiskChanging File Attributes Deleting a FileSave LP ,A You can now run, list, or edit the programStatements CommandsBASIC-80 Statements BASIC-80 Commands ContdBASIC-80 Functions BASIC-80 Statements ContdBASIC-80 Functions Contd Functions Representing DataInteger Constants ConstantsDecimal Integer Constants Hexadecimal Integer ConstantsOctal Integer Constants Single-Precision Floating-Point ConstantsDouble-Precision Floating-Point Constants String Variables String ConstantsThis is a string constant $ = Enter next data stringYI,1 L4! = Csng l4String Arrays BASIC-SO Operators in Order of Precedence Contd Arithmetic OperatorsString Operator Logical OperatorsNumeric Expressions String ExpressionsEntering and Editing Programs 30 A=8 30 A=8*5230 A=8*52 30 A=8*37 30 A--=8xx*522537 Control-R a = 8*37Command 3D press 3, then D results SubcommandInteger D If AB thenIf AB then 120 Else Null SET At this point, the other editing subcommands may be used Syntax of the X subcommand isInteger C character character Print Undefined SET The E subcommand is enteredMove the cursor to PRINT. Enter 2C RE L Print Undefined SET. Enter a LBASIC-80 Error Messages Syntax Error MessagesOverflow, Underflow, and Divide-by-Zero Error Trapping Trace Facility Error Handling Error SimulationRestarting Program Execution If line 40 is replaced withOpen 1,#1,F1DATES Opening a Sequential FileWriting to a Sequential File Refer to for further details of Print UsingReading from a Sequential File If executed four times, it would read all eight valuesValue of R$ would be Closing a Sequential FileBuffers Defining a Random 1/0 Field-FIELDField #3, 20 AS N$ Field #3, 20 AS N$, 9 AS SS$ Disk File Input/OutputReading from a Random 1/0 File Opening and Closing a Random Disk FileAny of the parameters can be variables To read the next recordInteger Writing to a Random 1/0 FileSingle-precision value Double-precision valueMKI$ Attrib Fdrive numberfilename, WO Attrib Fdrive numberfilename, W1Auto first lineJ, increment Clear expression,addressClose Commands and StatementsRules for function name are the same as for variable name DEF FNXDefsng Defdbl Defstr Defint Delete DIMDIR ErrorEdit ENDExit Error expressionField FOR-NEXT-STEPGosub GETFor variable=expression to expression Step expression GET I file number ,record numberIF-THEN-ELSE InputGoto LET KillLine Input ListLoad LSET, RsetNEW Merge9 16 NextOn ... Gosub On ... GotoOpen Option Base OUTPoke Print Using PrintString Fields If X$=SEVEN and Y$=EIGHT, the results of line 40 would be Numeric fieldsPUT PrunRead RandomizeREM Return ResumeRUN line numberlstring expression ,F SaveLine number RUN filename 60 END? 5,8,2 TRON, TroffWidth WaitATN ABSCHR$ CintFunctions CVI CVS Csng10 A# = 1.00/3.00 AO/o =EOF DskfOk· FIXHexs INPInputs INT InstrLEFT$ LOC LENLOF LOGMID$ MKI$ MKS$ MKD$OCT$ Peek expression RightsPOS integer RIGHT$ string,integerSIN SGNSpaces 10 a =1SPC integer SPCIf A$ = 2 then Print Correct Else Goto SQRexpressionSTR$ expression TAB expressionTAN expression 60 AO/o = Here is an example of how the USRn statement is usedTable A-I. BASIC-80 Error Codes Appendix a BASIC-SO Error CodesTable A-I. BASIC-SO Error Codes Contd Appendix B BASIC-SO Reserved Words Page Level To halt program execution and return to commandTo tab across the line To resume program execution after it is stopped byPage Appendix D Ascii Codes Table D-l. Ascii Code ListBEL Table D-2. Ascii Code DefinitionAppendixe Calling Subroutines Figure B-1. Internal Representation of Numbers and Strings RESULT=USR%1VARPTRA, VARPTRB, VARPTRC» PRINTA+B+C= Result Some Real ExamplesFigure E-2 /8085 Assembly Language Program Figure E-3. PL/M-80 Program Appendix F RMX/SO BASIC-SO ISIS-II BASIC-SO Initializing the Predefined RMX/SO BASIC-SO ConfigurationOOOOH-OFFFH Table F-l. Sample Configuration Jumper WiringBASIC-80 Source Files Generating Boot-Loaded and PROM-Based VersionsBASIC-80 Object Files BASIC-80 Executable FilesGenerating a Boot-Loaded RMX/80 BASIC-80 This option is used to allocate memory. It is 1 if the boot That are not boot loadedSetting baud rates, refer to the RMX/SO Users Guide This option enables your user-written I/O drivers if youISBC 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 Adding BASIC-SO to an Existing RMX/SO Configuration Configuring DFS on an iSBC 80/10Configuration Requirements ISBC SO/10 System ClockPublic Variables Open 0,#1, L1LlST Adding User-Written I/O Drivers to RMX/SO BASIC-SOFigure F-S. Sample User-Written 1/0 Driver Routine Burning a BASIC-80 Program Into Prom Altering BASIC-80 WorkspaceBaprom F1HEATER.BAS Page Index Ase BASIC-80 RIGHT$,7-1O Request for Readerscomments 111111