@acadiel
imho xta does only support up to 40 MB.
After spending some time on the interface I only see one solution for connecting cf-cards on xta bus:
- interface has to handle xta bus commands and datas
- interface has to handle ide bus commands and datas
- interface has to interpret commands and datas from xta bus to ide bus and vice versa
- and all very time critical
Might be the reason that up to now no solution exist.
A simpler solution may be possible if you drop the requirement to be compatible with the xta protocol and xta BIOS. The xta bus has two address bits (A0 and A1) that allow to select 4 8-bit registers, while the ide bus has three address bits (A0,A1,A2, for 8 registers) plus the CS1 signal to select two "alternate registers".
With some shuffling of the pins you can connect an IDE drive to an XTA interface, however only four registers will visible, depending on how you fix the missing A2 and CS1 signal.
So I am thinking that it may be possible to the following:
- use one of the xta registers (say, A0=0, A1=0) to select wich ide registers expose throug the other three xta registers
- create a custom version of the xt-ide unversal bios to support a cf-card in 8 bit mode
In this way the interface has to implement only the register remapping logic, and don't need to interpret nor translate protocols. The XUB variant takes care of setting the register remapping before accessing an IDE register.
I don't know how crazy or realistic this solution is, I am only speculating out loud here. If it works, it may be useful for scenarios where you can add an option rom or reflash the onboard xta bios but you don't have a free slot for an xt-ide card.
