Intel 9800758-02 manual Mki$

Page 40

Disk File Input/Output

BASIC-SO

Remember that random disk files are stored as strings. Just as you must convert fields that represent numeric values when you read them (using eVI, CVS, or CVD), so must you convert numeric values to their corresponding strings when writing to a random file, using the MKI$, MKS$, and MKD$ functions. Again, you must be sure to allow for the number of bytes required to store the three numeric data types.

Integer	MKI$	2 bytes
Single-precision value	MKS$	4 bytes
Double-precision value	MKD$	8 bytes

For example, assume that you open a random file and define two fields: the first 2 characters as P$ and the next 4 characters as C$; the first field represents a part number and the second its cost. The following statements open the file, set P$ equal to a variable P A and C$ equal to a variable CO, then write the two values to file number 5:

10OPEN "R", #5, ":F1 :PARTS"

20FIELD #5, 2 AS P$, 4 AS C$

30LSET P$ = MKI$ (PA)

40RSET C$ = MKS$ (CO)

50PUT#5, 1

The part number, of course, must be between -32768 and 32767, and the cost will be accurate to 7 digits.

Two other functions are related to random disk 110: LOC and LOF. LOF returns the number of the last sector in the file; LOC returns the number of the sector that was last read or written.

5~8

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Contents BASIC-SO Reference Manual A108/0979/7500 FL Preface Page Contents Illustrations Chapter Introduction to BASIC-80 Invoking BASIC-80Examples Introduction to BASIC-80Basic filename MEMTOPaddress FilenameListing the Directory of a Disk Renaming a FileChanging File Attributes Deleting a FileYou can now run, list, or edit the program Save LP ,ACommands StatementsBASIC-80 Commands Contd BASIC-80 StatementsBASIC-80 Statements Contd BASIC-80 FunctionsBASIC-80 Functions Contd Representing Data FunctionsConstants Integer ConstantsDecimal Integer Constants Hexadecimal Integer ConstantsSingle-Precision Floating-Point Constants Octal Integer ConstantsDouble-Precision Floating-Point Constants String Constants String VariablesThis is a string constant $ = Enter next data stringL4! = Csng l4 YI,1String Arrays Arithmetic Operators BASIC-SO Operators in Order of Precedence ContdLogical Operators String OperatorNumeric Expressions String ExpressionsEntering and Editing Programs 30 A=8*52 30 A=830 A=8*52 30 A=8*37 30 A--=8xx*522537 Control-R a = 8*37Subcommand Command 3D press 3, then D resultsInteger D If AB thenIf AB then 120 Else Null SET Syntax of the X subcommand is At this point, the other editing subcommands may be usedPrint Undefined SET The E subcommand is entered Integer C character characterMove the cursor to PRINT. Enter 2C RE L Print Undefined SET. Enter a LSyntax Error Messages BASIC-80 Error MessagesOverflow, Underflow, and Divide-by-Zero Error Trapping Trace Facility Error Simulation Error HandlingRestarting Program Execution If line 40 is replaced withOpening a Sequential File Open 1,#1,F1DATESRefer to for further details of Print Using Writing to a Sequential FileReading from a Sequential File If executed four times, it would read all eight valuesClosing a Sequential File Value of R$ would beDefining a Random 1/0 Field-FIELD BuffersField #3, 20 AS N$ Disk File Input/Output Field #3, 20 AS N$, 9 AS SS$Opening and Closing a Random Disk File Reading from a Random 1/0 FileAny of the parameters can be variables To read the next recordWriting to a Random 1/0 File IntegerSingle-precision value Double-precision valueMKI$ Attrib Fdrive numberfilename, W1 Attrib Fdrive numberfilename, WOAuto first lineJ, increment Clear expression,addressCommands and Statements CloseDEF FNX Rules for function name are the same as for variable nameDefsng Defdbl Defstr Defint DIM DeleteError DIREdit ENDError expression ExitField FOR-NEXT-STEPGET GosubFor variable=expression to expression Step expression GET I file number ,record numberInput IF-THEN-ELSEGoto Kill LETLine Input ListLSET, Rset LoadMerge NEWNext 9 16On ... Goto On ... GosubOpen OUT Option BasePoke Print Print UsingString Fields Numeric fields If X$=SEVEN and Y$=EIGHT, the results of line 40 would bePrun PUTRandomize ReadREM Resume ReturnSave RUN line numberlstring expression ,FLine number RUN filename 60 ENDTRON, Troff ? 5,8,2Wait WidthABS ATNCint CHR$Functions Csng CVI CVS10 A# = 1.00/3.00 AO/o =Dskf EOFFIX Ok·INP HexsInputs Instr INTLEFT$ LEN LOCLOF LOGMKI$ MKS$ MKD$ MID$OCT$ Rights Peek expressionPOS integer RIGHT$ string,integerSGN SINSpaces 10 a =1SPC SPC integerIf A$ = 2 then Print Correct Else Goto SQRexpressionTAB expression STR$ 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 CodesTable A-I. BASIC-SO Error Codes Contd Appendix B BASIC-SO Reserved Words Page To halt program execution and return to command LevelTo tab across the line To resume program execution after it is stopped byPage Table D-l. Ascii Code List Appendix D Ascii CodesTable D-2. Ascii Code Definition BELAppendixe Calling Subroutines Figure B-1. Internal Representation of Numbers and Strings Some Real Examples RESULT=USR%1VARPTRA, VARPTRB, VARPTRC» PRINTA+B+C= ResultFigure 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-SOTable F-l. Sample Configuration Jumper Wiring OOOOH-OFFFHGenerating Boot-Loaded and PROM-Based Versions BASIC-80 Source FilesBASIC-80 Object Files BASIC-80 Executable FilesGenerating a Boot-Loaded RMX/80 BASIC-80 That are not boot loaded This option is used to allocate memory. It is 1 if the bootSetting 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 Configuring DFS on an iSBC 80/10 Adding BASIC-SO to an Existing RMX/SO ConfigurationConfiguration Requirements ISBC SO/10 System ClockPublic Variables Adding User-Written I/O Drivers to RMX/SO BASIC-SO Open 0,#1, L1LlSTFigure F-S. Sample User-Written 1/0 Driver Routine Altering BASIC-80 Workspace Burning a BASIC-80 Program Into PromBaprom F1HEATER.BAS Page Index Ase BASIC-80 RIGHT$,7-1O Request for Readerscomments 111111