Board Initialization
VL-486-4 Reference Manual
Configuration – 41
82C836 I
NITIALIZATION
The Internal Configuration Registers (ICR) of the 82C836 are accessed using I/O ports 0022h
and 0023h. The initialization data must be written to the 82C836 immediately after CPU reset.
To initialize the 82C836:
1. Output the ICR index number to port 0022h.
2. Output the initialization data to port 0023h (see table).
3. Repeat steps 1 and 2 for all the registers.
Table 19: Chips & Technologies 82C836 Initialization Data
Initialization Data
Index
Number
2M
DRAM
4M
DRAM
Description
01h
00h
00h
DMA Wait-State Control Register
40h
—
—
Version Register
41h
08h
08h
Channel Environment Register
42h
—
—
Reserved
43h
—
—
Reserved
44h
01h
01h
Peripheral Control Register
45h
—
—
Miscellaneous Status Register
46h
01h*
01h*
Power Management Register
47h
—
—
Reserved
49h
00h
00h
RAM Write Protect Register
4Ah
00h
00h
Shadow RAM Enable Register 1
4Bh
00h
00h
Shadow RAM Enable Register 2
4Ch
00h
00h
Shadow RAM Enable Register 3
4Dh
0Bh
0Ch
DRAM Configuration Register
4Eh
59h
59h
Extended Boundary Register
4Fh
00h
00h
EMS Control Register
60h
00h
00h
Laptop Features
61h
—
—
Fast Video Control
62h
—
—
Fast Video RAM Enable
63h
B0h
B0h
High Performance Refresh
64h
03h
03h
CAS Timing for DMA/Master
* When DRAM parity detection is enabled, this should be 41h.