Web site: www.formosa21.com
MBM-530NS User’s Manual -15-
1.3 Keyboard Controller
The 8042 processor is programmed to support the keyboard serial interface.
The keyboard controller receives serial data from the keyboard, checks its
parity, translates scan codes, and presents it to the system as a byte data in
its output buffer. The controller can interrupt the system when data is placed in
its output buffer, or wait for the system to poll its status register to determine
when data is available.
Data can be written to the keyboard by writing data to the output buffer of the
keyboard controller.
Each byte of data is sent to the keyboard controller in a series with an odd parity bit
automatically inserted. The keyboard controller is required to acknowledge all data
transmissions. Therefore, another byte of data will not be sent to keyboard
controller until acknowledgment is received for the previous byte sent. The
“output buffer full” interruption may be used for both send and receive
routines.
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