UPD784938 Datasheet, PDF (481/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 20 IEBus CONTROLLER
20.3 IEBus Controller Configuration
Figure 20-10 shows the block diagram of the IEBus controller.
Figure 20-10. IEBus Controller Block Diagram
CPU interface block



Internal 
registers



8
BCR (8)
8
12
UAR (12)
12
12
SAR (12)
12
12
PAR (12)
12
8
CDR (8)
8
8
DLR (8)
8
8
8
DR (8) USR (8)
8
8
8
8
8
8
ISR (8) SSR (8) SCR (8) CCR (8)
8
8
8
8
RX
NF
TX
MPX
MPX
Internal bus
8
PSR (8 bits)
12
8
12-bit latch
TX/RX
Comparator
Parity generation
error detection
Contention
detection
Interrupt
control
circuit
INT request
(vector, macro
service)
Interrupt control block
IEBus interface block
ACK
generation
CLK
5 Internal bus R/W
Bit processing block
Field processing block
Preliminary User’s Manual U13987EJ1V0UM00
481