A
An
Hello!
From IBM PC/XT harware books,I know that PC's RS-232 port
uses SN75154 as RS-232 to TTL converting chip. The threshold
control pin is connected to VCC in the hardware book.so the
threshold voltage should be -1.1V,see the the figure.But it
seem's that is not the case,the threshold voltage is about
1.4V in modern computers. Who could please tell me how the
hardware about UART of modern computers changed?
----------------
An
From IBM PC/XT harware books,I know that PC's RS-232 port
uses SN75154 as RS-232 to TTL converting chip. The threshold
control pin is connected to VCC in the hardware book.so the
threshold voltage should be -1.1V,see the the figure.But it
seem's that is not the case,the threshold voltage is about
1.4V in modern computers. Who could please tell me how the
hardware about UART of modern computers changed?
----------------
An