[coreboot] Dual flash chip mod

[Ivan Barrera A.]

Peter Stuge escribió:
>>> A few cm should be fine but keep them as short as possible.
>>>
>>> You need pins 2 (7 8) (9 10 11 12) 13 14 15 16 17 24 25 28 29 31 32
>>>
>>> Hm, that's 12 but some are the same signal. The ID pins and MODE can
>>> probably be tied to either VDD or VSS but check their connections on
>>> the original chip first.
>> If we're dealing with FWH chips on ICH, you can solder both chips
>> on top of each other with all pins except ID0. ID0 needs to be
>> connected to a switch so that exactly one of them is high and the
>> other one is low.
> 
> Yes, good point, the CE in this case is ID0, and it should be
> switched. ID pins are internally pulled-down so the switch circuit
> actually becomes trivial. Disconnect original ID0 from mainboard.
> Connect middle contact of switch to VDD via a 1k resistor. Connect
> each side contact of switch to ID0 on the respective chips. The three
> leads to the switch can be pretty long.
> 
> If they are PLCC chips it isn't very practical to solder two chips on
> top of each other, because the chip leads bend in under the chip and
> do not reach the top. Every lead on the upper chip would have to be
> bent to continue straight down to maybe reach the leads on the lower
> chip. I don't know if the leads are actually long enough to make that
> work. Also needs a few mm for the chip package on top of the existing
> chip of course. Often it's easier to put the second chip somewhere
> else on the board, and run wires. Yes, that needs a little more work.

Besides,
   in the case of a laptop, one of top of the other is out of the 
question. There might be enough space around the newly installed socket, 
but on top, space is pretty limited. (this is, of course, in case of a 
laptop).

   I'll also subscribe to the flashrom list, and send the output of my 
board.


> 
> 
> //Peter
>