Identifying a 2GB Compact Flash card to work with an older DynaTem CPU board.

I have an older (2004) Dynatem CPU which uses an On-board CF slot which the CPU boots and runs a Linux (RedHat 9) operating system.  We have been using a Lexar 2GB CF card (CF2GB-80-380) which currently works just fine.

The Lexar part has none gone obsolete, and we are trying to specify a 2GB CF card to replace it.  We tried experimenting with a Sandisk (Ultra P/N SDCFH-002G-A11) but the CPU Card would fail to read the partition tables on the CF device,

We contacted the vendor, and they informed us that the Card slot is not set up for DMA transfers as some of the control line for DMA are not brought through to the CF slot, specifically, DMA REQ and ACK.

So, does Sandisk make a CF card that will work natively in PIO mode and ignore the missing DMA control signals?

Thanks for you help.

all sandisk UDMA compatible cards can work in either UDMA or PIO mode. if UDMA is not present it should default to PIO mode. 

all sandisk cards that support UDMA support both UDMA and PIO. if UDMA is not present it will default to PIO transfer mode. 

Thanks for your responce but my problem still exists.  I suspect the way the SanDisk CF card identifies itself to the operating system may be my problem.

During the Linux boot process, I notice the following information from a query to the CF (identified as hdc)

hdc: 3928176 sectors (2011 MB) w/1Kib Cache, CHS = 3897/16/63,  (U) DMA

The operating system then tries to query the CF using DMA commands which then timeout cuasing the partions to not be read.

The Lexar CF identifies itself in a similar fashion but without the “(U) DMA” in the identification string.

My question is then is it possible to modify the CF to no long put the "(U)DMA in the identifing string?



I just wanted to let you know that I found a solution to my problem.

Using the kernanl parameter ide=nodma, forces the operating system to not use the dma mode when communicating with the CF device.

i.e. kernel /boot/vmlinuz-2.6.18-4-686 ide=nodma root=/dev/hda1 ro

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