UPD784938 Datasheet, PDF (492/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 20 IEBus CONTROLLER
(8) Unit status register (USR)
Figure 20-22. Unit Status Register (USR) Format
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4
3
2
1
USR 0 SLVRQ ARBIT ALLTRNS ACK LOCK 0
0 Address After reset R/W
0 0FFBBH 00H
R
LOCK
Lock Status Flag
0 Non-lock status
1 Lock status
ACK
ACK Transmission Flag
0 Transmits NACK
1 Transmits ACK
ALLTRNS Broadcasting Communication Flag
0 Individual communication status
1 Broadcasting communication status
ARBIT
Contention Flag
0 Wins in contention
1 Loses in contention
SLVRQ
Slave Request Flag
0 No slave request
1 Slave request
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Preliminary User’s Manual U13987EJ1V0UM00