On 5 Feb 2010 at 17:01, Dave McGuire wrote:
8255s are frequently used to interface to IDE
drives, and mode
switching is required in that application, and it does get in the
way. Mostly people have dealt with it by using inverters on some of
the lines.
Really? I don't think I've seen a single piece of modern gear made
in the last 10 years that uses an 8255 to interface to an IDE drive.
They do have specialized chips to do that...
An 8255 is a ridiculous choice to interface to an IDE drive!. I've never
seen it used for that either. The IDE card in this machine uses a few TTL
buffers and a couple oF PALs for address decoding, etc.
If it's the hobbyist clan, well, that's a different matter. I'd
think even a small CPLD would do a better job.
This assumes you have the facilities to program the CPLD, the development
software _and somethign to run it on_. That is not always the case.
-tony