I have my IDE drive memory mapped to a 8051, and was able to read and write to the drive, please search this forum for other posts on this subject as I remember posting details about how I used the drive in LBA mode. If I remember correctly you have to set the drive mode correctly before using it.

For info mine is mapped so that the low 8 bits are directly connected to the 8051 data bus, and the upper 8 bits are 2 x 8 bit latches that I write to first, the second write to the low 8 bits also wites the upper bits from the latches, the read is similar in that all 16 bits are read, the lower directly and the upper bits latched, these upper bits are then read bu a second read to the location of the latch.

I have this implemented using 2 x 245's and 2 x 574's , but I am currently changing this so that it's all in a CPLD.