Z85C3010VSG Datasheet, PDF (38/83 Pages) Zilog, Inc. – CMOS SCC Serial Communications Controller

CMOS SCC Serial Communications Controller
Product Specification
30
Read Operation
When WR15 bit D2 sets and the FIFO is not empty, the next read to status register RR1 or
registers RR7 and RR6, is from the FIFO. Reading status register RR1 causes one location
of the FIFO to become empty. Status is read after reading the byte count, otherwise the
count is incorrect. Before the FIFO underflows, it is disabled. In this case, the multiplexer
is switched allowing status to read directly from the status register. Reads from RR7 and
RR6 contain bits that are undefined. Bit D6 of RR7 (FIFO Data Available) determines if
status data is coming from the FIFO or directly from the status register, which sets to 1
when the FIFO is not empty. Not all status bits are stored in the FIFO. The All Sent, Parity,
and EOF bits bypass the FIFO. Status bits sent through the FIFO are Residue Bits (3),
Overrun, and CRC Error.
PS011707-1013
Functional Descriptions