DP8344 datasheet(56/184 Pages) NSC

56 / 184 page

30 Transceiver (Continued)

lates odd parity on the data byte (B2 – B9) and transmits this

value for B10 If TCR 2

is high B10 takes the state of

TCR 0

Odd Word Parity OWP controls the type of

parity calculated on B1 – B11 and transmitted as B12 the

frame delimiter If OWP is high odd parity is output other-

wise even parity is transmitted In this manner the system

designer is provided with maximum flexibility in defining the

transmitted 3270 control bits (B10 – B12)

When data is written to RTR

the least significant 4 bits of

TCR are loaded into the FIFO along with the data being

written to RTR

The same TCR contents can therefore

be used for more than one frame of a multi-frame transmis-

sion or changed for each frame

When a 3270 frame is received and decoded the decoder

loads the parallel data into the receive FIFO where it propa-

gates through to the last location and is mapped into RTR

and TSR

Bits B2 – B11 are exactly as received Byte Pari-

ty BP is odd parity on B2 – B9 calculated in the decoder

Reading

RTR

will advance the receive FIFO therefore

TSR must be read first if this information is to be utilized

TLF9336 – 47

(a) 3270 Data and Command Frames

TLF9336 – 48

(b) 3299 Address Frame

FIGURE 3-9 32703299 Frame AssemblyDisassembly Procedure

DP8344 Datasheet(PDF) 56 Page - National Semiconductor (TI)