I am porting the northbridge 82845e for my
motherboard. While coding
raminit.inc file, I took the file from the 82830 chipset directory and
modified as per the requirement of the 82845e chipset. Now I want to know,
How to get the register value of the regsiters, like DRB DRAM ROW BOUNDARY
REGISTER and etc. Do I need to read these regsiter value from the system
using normal BIOS? I could not find much details about the values in the
specification. Is my assumption is correct?
At least on the 430tx, the DRB is programmed with the highest amount of memory
in each row, in 4MB chunks.
In my particular case, I have one single 64M dual-sided SODIMM in Row 0. So
my DRB0 has a value of 0x10 (16*4 = 64) and DRB1-5 have the same value since
they are not adding any memory.
Realistically you should be using a memory detection algorithm to try and find
out how much memory is at each row and then programming the DRB registers
correctly. I have never done this, though.