Community QBasic

Rebooting the QBasic we all know and love!

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Project maintained by Cory Smith

OPEN

To establish input/output (I/O) to a file or device.

Syntax

OPEN filename [ FOR access_mode ] [ ACCESS network_access ] [ lock_type ] AS [#] file_number [ LEN = record_length ]

OPEN mode, [#] file_number, filename [ , record_length ]

OPEN "COMn: basic_com com_specifics” [ FOR access_mode ] AS [#] file_number [ LEN = record_length ]

Comments

filename is a string expression containing the name of the file or device to open.

access_mode specifies how the file is to be used: INPUT, OUTPUT, APPEND, RANDOM or BINARY. The default is RANDOM.

network_access provides more detail on how the file is to be used in shared-file network environments: READ, WRITE or READ WRITE.

lock_type is the type of file locking used in shared-file environments: SHARED, LOCK READ, LOCK WRITE or LOCK READ WRITE.

file_number is the integer number to associate with the file for read, write and close operations.

record_length is the number of bytes in each record. For sequential files, the default is 512; for random-access files, the default is 128; for communications, the default is 128. The value cannot exceed 32,767.

mode is used for older BASIC programs. It is a single-letter string that specifies the access mode:

• A Append
• B Binary
• I Input
• O Output
• R Random

n is the number of the communications port to open, either 1 or 2.

basic_com represents the basic data-communications parameters, separated by commas, in the following form:

[ baud ] [ ,[ parity] [, [ databits ] [ , [ stopbits ]]]]

• baud is the baud rate of the device used: 75, 110, 150, 300, 600, 1200, 1800, 2400, 4800, 9600 or 19200.
• parity is the parity of the device used: N (none), E (even), O (odd), S (space), M (mark) or PE (enable error checking).
• databits is the number of bits in each data word: 5, 6, 7 or 8. The sum of parity bits and data bits must be less than or equal to 8. If the parity is set to O (odd) or E (even), one bit is used for parity. If parity is set to N (none), no bits are used for parity.
• stopbits is the number of stop bits for each word: 1, 1.5 or 2.

com_specifics is a list of data-communications specifics, separated by commas:

• ASC opens device in ASCII mode
• BIN opens device in binary mode
• CD[ milliseconds ] specifies carrier-detect timeout
• CS[ milliseconds ] specifies clear-to-send timeout
• DS[ milliseconds ] specifies data-set-ready timeout
• LF sends linefeed after each carriage return
• OP[ milliseconds ] specifies the OPEN statement timeout period
• RB[ bytes ] specifies the size of the receive buffer
• RS suppresses detection of Request To Send (RTS)
• TB[ bytes ] specifies the size of the transmit buffer

Example

OPEN "TEST.DAT" FOR INPUT AS #1

f% = FREEFILE
OPEN "NEW.DAT" FOR RANDOM AS f% LEN = 80

OPEN "C0M1:4800, E, 7, 1, BIN" AS #2

See Also

• CLOSE, FREEFILE