How to read whole compact flash card

[yys2000]

Hi:
I has a compact flash card. And I want to read whole compact flash card.
It has been formatted by Linux and has three partitions. It also has a pre-partition part which contains all important information.
When I plug it in, Linux will mount three partition automatically as: sdb2,sdb5,sdb6. Linux will not mount the pre-partition part, so I can not read the part.
My question is how can I read whole compact flash card?
Can I build a raw device and read the whole raw device byte by byte? If yes, how can I do it?

thx

[yys2000]

The pre-partitopn part starts with sector 1. Maybe ends in sector 2. And all three other partitions start with sector 3.
So maybe my question should be: How can I read whole compact flash card starts from sector 1?
I have to use raw device? or any other open source tool to read?

thx!