Used by the routine at E4AD.

any logical file that has already been opened by the OPEN routine, FFC0, can be defined as an output channel by this routine the device on the channel must be an output device or an error will occur and the routine will abort.

if you are sending data to anywhere other than the screen this routine must be called before using the CHROUT routine, FFD2. if you are sending data to the screen and no other output channels are open then the calls to this routine and to the OPEN routine, FFC0, are not needed.

when used with a device on the serial bus this routine will automatically send the listen address specified by the OPEN routine, FFC0, and any secondary address.

possible errors are:

• 3 : file not open
• 5 : device not present
• 7 : file is not an output file