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Number $143B
Decimal 5179
Short desc. Reads data from serial port, write sets the baudrate
Bit Mask %0001 0100 0011 1011
Readable Yes
Writable Yes
Subsystem UART

Read a byte from the receive buffer. If the buffer is empty, 0 is returned.

Writes the lower 14-bits of the UART's prescalar value that determines baud rate

If bit 7 = 1
bits 6:0 = upper 7-bits of the 14-bit prescalar value
If bit 7 = 0
bits 6:0 = lower 7-bits of the 14-bit prescalar value

The UART's baud rate is determined by the prescalar according to this formula:

prescalar = Fsys / baudrate ; Fsys = system clock from Video Timing Register ($11)

Eg: If the system is HDMI, nextreg 0x11 indicates that Fsys = 27000000. The prescalar for a baud rate of 115200 is 27000000 / 115200 = 234.