PERIPHERAL INTERFACING – III 415
sync operation and writes two dummy 00 sync characters. An internal reset command may then
be issued to bring the chip to the idle state. e following sequence of instructions must precede
the program lines of Examples 11.3 and 11.4
MOV AL, 00 ;AL = 00
OUT CSR, AL ;send AL to CSR
OUT CSR, AL ;send AL to CSR
OUT CSR, AL ;send AL to CSR
MOV AL, 01000000B ;command word with D
6
= 1
OUT CSR, AL ;send to CSR for internal reset
The Serial Port of the PC
As already mentioned, the PC supports only asynchronous serial communication. It uses the
UART chip 8250 for interfacing. is chip is, incidentally, a more powerful chip than the
8251. e 8250 was improved along the years that the processors used ...