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Intel386™ EX EMBEDDED MICROPROCESSOR USER’S MANUAL
11-24
11.3.5 Receive Buffer Register (RBR
n
)
Read RBRn to obtain the last data word received. Use the interrupt control or DMA units or poll
the serial line status register (LSRn) to determine whether the receive buffer is full.
Figure 11-14. Receive Buffer Register (RBR
n
)
Receive Buffer
RBR0, RBR1
(read only)
Expanded Addr:
ISA Addr:
Reset State:
RBR0 RBR1
F4F8H F8F8H
03F8H 02F8H
XXH XXH
7 0
RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0
Bit
Number
Bit
Mnemonic
Function
7–0 RB7:0 Receive Buffer Bits:
These bits make up the last word received. The receiver shifts bits in,
starting with the least-significant-bit. The receiver then strips off the
asynchronous bits (start, parity, and stop) and transfers the received
data bits from the receive shift register to the receive buffer.
NOTE: The receive buffer register shares an address port with other SIO registers. Bit 7 (DLAB) of
the LCR
n
must be cleared in order to read the receive buffer register.