I have realized an HDD Interface to an DS80C320. Now i am modifing the desing to have an EPROM with a bootloader that can store the data into an SRAM with 20ns. the data is coming from the serial port as an HEX file or from the harddisk (in future via FTP). after downloading (from what source ever) it reboots and starts executing from the SRAM.
This makes me very flexible. i do not need to programm any eprom again, i do not need to use an eprom-sim. and i can download lot's of old version from the harddisk within a short time.
this is faster as a flash solution.

As i goody, i have implemented the CS8900A 10Mbaud Ethernet Chip as Well, but this source is still empty. (no time for this yet)

Unfortunatly it is very hard to get eproms with 40nsec tacc so but i am working on that. The design will run at 33MHz and if the DS80C390 becomes available here in Germany. The layout will have a place for it running at 40MHz (thats the reason for 20nsec SRAM)

The SRAM will be bankswitched if SDCC will support this .... please Sandeep ..

Back to your question, the IF is more than simple. some guys here talked about using an 8255 and such strange and too complicated solutions. you just need some 573 latches to store the upper / lower data while reading / writing the HDD in 16-Bit mode. an 245 and some pure logics. The HDD can only do data io in 16-bit mode. some regs are 8-bit wide(short). The software is more than simple. just a reset cmd, a recall, a get drive params, and then start reading or writing. you will need a buffer as the HDD stores data in blocks of 512bytes.

If you can wait a few more weeks, a will post the web page where you can download HW & SW (maybe gerber also).

But first comes my childs, my wife, my house and then this project. So check out the SDCC open knowledge resource web page.