OPEN

Action: This statement OPENs a channel for input and/or output to a peripheral device. However, you may NOT need all those parts for every OPEN statement. Some OPEN statements require only 2 codes:

1. LOGICAL FILE NUMBER
2. DEVICE NUMBER

The <file-num> is the logical file number, which relates the OPEN, CLOSE, CMD, GET#, INPUT#, and PRINT# statements to each other and associates them with the file-name and the piece of equipment being used. The logical file number can range from 1 to 255 and you can assign it any number you want in that range.

Each peripheral device (printer, disk drive, cassette) in the system has its own number which it answers to. The <device> number is used with OPEN to specify on which device the data file exists. Peripherals like cassette decks, disk drives or printers also answer to several secondary addresses. Think of these as codes which tell each device what operation to perform. The device logical file number is used with every GET#, INPUT#, and PRINT#.

If the <device> number is left out the computer will automatically assume that you want your information to be sent to and received from the Datassette^TM, which is device number 1. The file-name can also be left out, but later on in your program, you can NOT call the file by name if you have not already given it one. When you are storing files on cassette tape, the computer will assume that the secondary <address> is zero (0) if you omit the secondary address (a READ operation).