So I'm trying to write a tiny operating system for the TI, and I'd like to avoid as much of TI's original design decisions as possible. This is mostly for the challenge of it and to see if whatever I can come up with is better then what the original engineers made. This would also let me make maximum use of the limited hardware resources.
My most basic problem is that I need to do my development on an emulator since my actual hardware is packed away at the moment. So my first question is if there are any Ti99/4a emulators which permit direct access to the FD1771 floppy controller. I'm pretty sure Classic99 does not do this, but I think MESS does.
I tried writing a really basic driver for the FD1771 and ran it in MESS. The problem I had there was that any attempt to read from the disk failed. I was able to get a lot of functions working properly, but when I tried to read a sector, I only got the first byte. After that I got "disk not ready" errors.
I've been using Thierry Nouspikel's code as a starting point, along with dumps of the floppy controller firmware and the FD1771 datasheet.
That's a bunch of text. Here's the short version:
1) Does anyone know of an emulator that emulates the floppy controller hardware?
2) Has anyone come across code which directly interfaces with the floppy controller, bypassing the DSR?
I've included the code I'm using under the spoiler tag.