Communications Mode
CP 523
Figure 7-14. Transfer Memory Assignments for "Receive Message Frame"
CPU writes word 0
CPU writes word 0
Word 0
Data
CP transfers last message
block from Receive mailbox
to transfer memory
CP transfers 1st message
block from Receive mailbox
to transfer memory
CP transfers further
message blocks from
Receive mailbox to transfer
memory
Word 6
Data
CPU reads last message block ( 8 byte)
CPU reads further message blocks (8 bytes each)
If no message frame in
Receive mailbox, end here!
CPU reads 1st message block (8 bytes)
Word 0
Data
Word 2
Data
Word 4
Data
Word 6
Data
Word 0
Data
Word 2
Data
Word 4
Data
Word 6
Data
Word 2
Data
Word 4
Data
CPU issues "Receive message" request
CPU reads coordination information
Word 0
Job No.
A080
H
Word 2
Not
significant
Word 4
Not
significant
Word 6
Not
significant
Word 6
Byte 6/byte 7:
No. of message
blocks/No. of
message
frames
CP reads job request from
transfer memory and writes
coordination information
into transfer memory
CPU user program
CP functions
Word 0
Data
CPU writes word 0
Word 0
Data
8-byte
trans-
fer
memo-
ry in
CP 523
Word 0
Data
Word 0
Coordination
information
and CBR:
Coordination
byte 'receive'
*
Word 2
Message
frame
length
(in bytes)
Word
4
Not
signifi-
cant
*
Relevant only in 3964(R) mode.
7-74
EWA 4NEB 811 6044-02a
