On 12/11/09 8:39 PM, ron minnich wrote:
On Wed, Dec 9, 2009 at 2:57 AM, Andrew Goodbody andrew.goodbody@tadpole.com wrote:
Luc Verhaegen wrote:
We have 892 bytes to our disposal in cmos. We can reserve 128 for board/cmos versioning, and reserve even 256 for the bootloader, and still have 512bytes left for coreboot options, which is tons when bits are used properly and when strings are not used.
Most boards I have used have a maximum space of 256 bytes that includes the RTC. Where does the extra come from?
On much of my hardware, the most I can assume is 128 bytes - subtracting many bytes that are weirdly hardware controlled (such as date).
Some of our hardware has 256 bytes.
The io ports only support an 8-bit address I thought?
The ports 0x70/0x71 even only support 7 bits... The 8th bit is used for NMI control.
Higher CMOS bytes can be accessed by 0x72/0x73, 0x74/0x75....
However, if you try to access the upper 128 bytes by setting the topmost bit in 0x70 it will just look like the upper 128 byte are a mirror of the lower 128 bytes.
Stefan