Open a disk file, or a TCP client stream. Stream numbers are 1 to 10.
OPEN file$ [FOR INPUT|OUTPUT|APPEND] AS #n OPEN “TCP:host:port” [FOR INPUT|OUTPUT] AS #n
file$ - disk path #n - stream number 1 to 10 INPUT - read OUTPUT - create/truncate APPEND - write at the end
OUTPUT and APPEND open the file immediately. APPEND creates it when missing, even if nothing is written. A file or drive that cannot be written reports ?FILE at OPEN, so an OPEN/CLOSE pair can check whether a drive is writable. On the A: ramdisk and the desktop C:-H: drives, missing parent folders are created automatically; on an SD-card or USB FAT volume they must already exist.
TCP: host is an IP or DNS name; port is required. No FOR means both directions. One TCP client at a time. CONNECT and TERM use the same socket. TCP requires an active network (Wi-Fi or Ethernet); without one, OPEN reports network not available.
Example:
OPEN "A.TXT" FOR OUTPUT AS #1
PRINT #1, "HELLO"
CLOSE #1
OPEN "TCP:192.168.1.50:80" AS #1Source: docs/help/open.txt inmmcore. On the computer, typeHELP OPEN.