Basic computer language commands

Basic computer programming language

IOCTL Statement

Purpose:

To allow GW-BASIC to send a "control data" string to a character device driver anytime after the driver has been opened.

Syntax:

IOCTL[#]file number,string

Comments:

file number is the file number open to the device driver.

string is a valid string expression containing characters that control the device.

IOCTL commands are generally 2 to 3 characters followed by an optional alphanumeric argument. An IOCTL string may be up to 255 bytes long, with commands within the string separated by semicolons.

Examples:

If a user had installed a driver to replace lpt1, and that driver was able to set page length (the number of lines to print on a page before issuing a form feed), then the following lines would open the new lpt1 driver and set the page length to 66 lines:

OPEN "LPT1:" FOR OUTPUT AS #1
IOCTL #1, "PL66"

The following statements open lpt1 with an initial page length of 56 lines:

OPEN "\DEV\LPT1" FOR OUTPUT AS #1
IOCTL #1, "PL56"

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