[rescue] CF + IDE in Tandy 1000RL?

Barry Callahan barryc at rjlsystems.com
Thu Jul 14 15:02:16 CDT 2011

On 07/14/2011 03:46 PM, Nate Raymond wrote:
> CF uses the IDE protocol but in a different pinout.  IDE to CF doesn't touch
> the protocol, it just adapts the connector.  However, I have read reports
> that some adapters are made better than others and work better than others,
> but I've never read an explanation of exactly why that would be.

Most CF->IDE adapters basically just reroute the pins as necessary, and 
have only the required passive components to signal the card to enter 
IDE mode.  Some adapters provide better power supply buffering than 
others. Some adapters also provide buffering on the address and data 
lines to ensure clean transitions between the voltage levels.

> CF cards typically report themselves as removable media, which an IDE hard
> drive never would, and that can cause problems when using a CF card in place
> of hard drive for some controllers or operating systems.  Years ago SanDisk
> provided a proprietary utility at customer's request for changing how their
> CF cards report themselves, but they stopped providing it at some point,
> though I did find a copy elsewhere on the internet a few years back.

Got a link?

> Different brands of CF cards have different controllers, and some support
> DMA, and some don't.  DMA support can be important when using CF cards with
> certain IDE controllers (I've seen lack of DMA support cause issues when
> trying to use some CF cards as boot devices with at least some operating
> systems).  I want to say SanDisk also had a utility for turning DMA on and
> off on their CF cards, but I'd have to go digging to verify that.

For Ethan's specific application, I highly doubt that DMA is going to be 
an issue. If he's worried about compatibility with XT IDE, chances are, 
the controller only supports PIO Mode 0. ( 

Try to stick with older, smaller CF cards, preferably <= 512MB and I 
expect you'll maximize your chances of the controller on the CF card 
understanding the protocol version(s) spoken by your controller.

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