| Com (hardware Interface) |
Article Index for Com |
Website Links For Com |
Information AboutCom (hardware Interface) |
|
Most PC-compatible systems in the 1980s and 1990s had one or two ports, with communication interfaces defined like this:
As of 2007 , most systems ship with one or no physical COM ports. I/O ADDRESSES The COM ports are interfaced by an integrated circuit such as 16550 UART . This IC has seven internal 8-bit Registers which hold information and configuration data about which data is to be sent or was received, the Baud Rate , interrupt configuration and more. In the case of COM1, these registers can be accessed by writing to or reading from the I/O Address es 0x3F8 to 0x3FF. If the CPU, for example, wants to send information out on COM1, it writes to I/O port 0x3F8, as this I/O port is "connected" to the UART IC register which holds the information that is to be sent out. SEE ALSO |
|
|