494 emulation

[sboy...@gmail.com]

I've spent a bit more time on the 494 / 1230 emulation and I have the real-time executive that Joe Cousins provided working. The time between invocation of the various routines seems reasonable but I doubt if they are millisecond accurate. I wouldn't try to use this for process control :) . You can download the latest version of the emulator including the real-time exec here:

https://www.dropbox.com/s/jvxojhek1kdp428/U494.exe?dl=0