Home > CBM > BASIC > Keywords > Restore
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| Keyword | Abbreviation | Token (hex) | Version(s) | Classification | | RESTORE | RE{Shift+S} | 8C | 1.0 to 7.0 | Command and Statement |
RESTORE [ lineNumber ] ... | Parameters | Type | Legal Value(s) | Default Value | Note(s) | | lineNumber | Unsigned Integer | 0 ~ 63999 | first line of program | Only valid in v3.5+; lineNumber must exist if specified |
Internal BASIC state management / user DATA access management.
The statement resets the secret DATA pointer to (by default) the beginning of the program. In a way, it is the opposite of READ (which advances the DATA pointer). Without a lineNumber, this statement simply allows the program to re-read DATA that has previously been READ. It might be used to re-set the initial state of the program; or it might be used to READ the same DATA a second (third, etc.) time for some other use (parallel/duplicate arrays maybe). With a lineNumber (only available in v3.5+), the possibilites increase a lot. Instead of simply re-setting the DATA pointer (like rewinding a tape), it allows for random access to DATA (almost) anywhere in the program (like a random disk file). Almost anywhere means the RESTORE statement can only set the DATA pointer to the start of a program line. Most DATA statements have multiple values, but there is no way to specify which one (it always sets the DATA pointer to the start of a line). If a lineNumber is specified, it must exist or an UNDEF'D STATEMENT ERROR is generated. The lineNumber need not have DATA statements on it; in this case, some later line in the program should have DATA statements (otherwise the next READ would generate OUT OF DATA ERROR). Example:
NEW
READY.
10 DATA SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY
20 FOR I = 1 TO 7
30 READ D$(I) : NEXT : REM initialize table
40 RESTORE : REM reset data pointer
50 READ N$: PRINT N$: REM re-read first item, and print it
RUN
SUNDAY
READY.
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That isn't a very practical example... you could just PRINT D$(1) instead of re-reading the data!
But hopefully it makes the action of RESTORE clear to you.
CHAR, CLR, DLOAD, GOTO, LOAD, LOCATE, MOVSPR, NEW, RECORD, RUN, TAB
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