External Devices

Control External Devices.

1. A device that OS recognizes as an ordinal file.
   This can be controlled as an usual file.
   
2. A device that are connected to a serial port.
   This can be handled as an usual file with the file name COM1, COM2, and so on.
   Refer to COM-ports(RS-232C).
   
3. A device that becomes a virtual COM-port
   This can be used as usual. COM-port numbers above 10 can be used.
   
4. A device with Windows API compatible driver.
   Refer to DLL and Win32 API (BASIC HELP), How to use Win32 API
   
5. A deice with ActiveX.
   OLE automation, OLE Automation (OCX).
   
6. A device that is connected to a parallel port.
   When manipulating I/O ports of CPU directly is required, use VBIOSCM libraly.
   Refer to How to use a DLL.
   

In any case, be careful with the character coding and the line end code.

When you want to manipulate a byte as a character, write
OPTION CHARACTER BYTE
on each program unit.

Line end code can be assigned for an opened file as follows.
SET #n ENDOFLINE CHR$(13)
This sets CR as the line end code.
When the Line end code is LF, CHR$(13) should be replaced by CHR$(10).
When the opposite uses CR+LF as the line end, this SET statement is not needed.

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