NEC uPD98502 System Controller

CHAPTER 1 INTRODUCTION
28 Preliminary User’s Manual S15543EJ1V0UM
1.5.3 System controller
System Controller is
µ
PD98502’s internal system controller. System Controller provides bridging function among
the VR4120A System Bus “SysAD”, NEC original high-speed on-chip bus “IBUS” and memory bus for
SDRAM/PROM/Flash.
Features of System Controller are as follows;
•Implements 4-word prefetch FIFO buffer between SysAD and Memory
•Implements 32-bit×64-word FIFO buffer for each Tx and Rx to IBUS
•Implements 32-bit× 4-word FIFO buffer for each Tx and Rx to HBUS
•Provides bus bridging function among SysAD bus and IBUS (internal bus) and Memory
•Supports Endian Converting function on SysAD bus
•Can directly connect SDRAM (MAX. 32 MBytes) and PROM/Flash (MAX. 8 MBytes) memory
•Supports all VR4120A bus cycles at 66 MHz or 100 MHz
•PROM/Flash data signals multiplexed on SDRAM data signals
•Supports 266-MB/sec (32 bits @66 MHz) bursts on IBUS
•Generates NMI and INT
•Supports NS16550 compatible Universal Asynchronous Receiver/Transmitter (UART)
•Supports separated 2-ch Timer
•Supports Deadman’s Switch Unit (Watch Dog Timer)
•Supports Micro Wire interface
Figure 1-5. Block Diagram of System Controller
System Controller
IBUS
SysAD BUS
PHB
PBUS-HBUS Bridge
PFUR
FAST-U ART
HARB
HBUS Arbiter
IHB
IBUS-HBUS Bridge
Flash
PROM
SDRAM
RS-232C/Micro Wire
HBUS
HBUS
HBUS
PBUS
ROM-IF
SDRAM-IF
System
Bridge
Memory
Arbitor
HBUS
MIF HIF
VRIF
DSU
TIMER
REGISTER