VT82C686B

Manufacturer Part NumberVT82C686B
ManufacturerETC-unknow
VT82C686B datasheet
 


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Page 33/128:

Register Overview

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Register Overview

The following tables summarize the configuration and I/O
registers of the VT82C686B. These tables also document the
power-on default value (“Default”) and access type (“Acc”)
for each register.
Access type definitions used are RW
(Read/Write), RO (Read/Only), “—” for reserved / used
(essentially the same as RO), and RWC (or just WC) (Read /
Write 1’s to Clear individual bits). Registers indicated as RW
may have some read/only bits that always read back a fixed
value (usually 0 if unused); registers designated as RWC or
WC may have some read-only or read write bits (see
individual register descriptions for details).
Detailed register descriptions are provided in the following
section of this document. All offset and default values are
shown in hexadecimal unless otherwise indicated
Revision 1.71 June 9, 2000
R
EGISTERS
Table 2. System I/O Map
Port
Function
00-1F
Master DMA Controller
20-3F
Master Interrupt Controller 0000 0000 001x xxxn
40-5F
Timer / Counter
60-6F
Keyboard Controller
(60h)
KBC Data
(61h)
Misc Functions & Spkr Ctrl 0000 0000 0110 xxx1
(64h)
KBC Command / Status
70-77
RTC/CMOS/NMI-Disable 0000 0000 0111 0nnn
78-7F
-available for system use-
80
-reserved- (debug port)
81-8F
DMA Page Registers
90-91
-available for system use-
92
System Control
93-9F
-available for system use-
A0-BF
Slave Interrupt Controller
C0-DF
Slave DMA Controller
E0-FF
-available for system use-
100-CF7
-available for system use*
CF8-CFB PCI Configuration Address 0000 1100 1111 10xx
CFC-CFF PCI Configuration Data
D00-FFFF -available for system use-
* On-Chip Super-I/O Functions – PC-Standard Port Addresses
200-20F
Game Port
2E8-2EF
COM4
2F8-2FF
COM2
378-37F
Parallel Port (Standard & EPP)
3E8-3EF
COM3
3F0-3F1
Configuration Index / Data
3F0-3F7
Floppy Controller
3F8-3FF
COM1
778-77A
Parallel Port (ECP Extensions) (Port 378+400)
-27-
VT82C686B
Actual Port Decoding
0000 0000 000x nnnn
0000 0000 010x xxnn
0000 0000 0110 xnxn
0000 0000 0110 x0x0
0000 0000 0110 x1x0
0000 0000 0111 1xxx
0000 0000 1000 0000
0000 0000 1000 nnnn
0000 0000 1001 000x
0000 0000 1001 0010
0000 0000 1001 nnnn
0000 0000 101x xxxn
0000 0000 110n nnnx
0000 0000 111x xxxx
0000 1100 1111 11xx

Register Overview