11. System Registers
ÛZIATECH
69
System Register 2
Digital I/O ASIC System Register 2
7
6
5
4
3
2
1
0
DSB RSV
BRAM
RSV PFN SBN
Register:
Address:
Access:
System Register 2
E4h
Read and Write
STD Bus NMIRQ (Input)
0 Inactive
1 Active
Power Fail NMIRQ (Input)
0 Inactive
1 Active
VMX
Reserved for Ziatech
Static RAM Block Selection (Output)
00 1st 32 Kbyte Block
01 2nd 32 Kbyte Block
ZT8907F11-02
Video Multiplex (Output)
0 Inactive
1 Active
Reserved for Ziatech
†
Always write these bits as zero.
Disable STD Bus Access
0 Normal
1 Disable STD bus access
†
10 3rd 32 Kbyte Block
11 4th 32 Kbyte Block
Mapped at
D8000h-DFFFFh
†
†
†
†
††
††
Register bits managed by Ziatech operating system software.