Hi Chuck I was thinking you had information on one of the controller boards based on the 8X300 with the WD11xx parts. I've already gotten enough information on both the WD11xx and the 8X300 to create a simple disassembler. I also needed some hardware specific inputs because the board I'm looking at does specific hardware fuctions based on the address that the 8X300 is executing ( similar to many bit slice designs ). This required a custom disassembler. I'm told that the TRS-80 Model4 used these parts for their hard disk controller. From looking at the code I have extracted code from WD's original application notes. I'd suspect the same for the TRS-80 controller as well. I noticed that there is a reset action that doesn't effect the M20's controller since it is used for DMA circuits that are not even connected in this controller. I suspect this was in the original app note. I'll have to do a little net digging on the TRS-80. I suspect I'll come up with the controller commands from the computer side. These are what I'm actually looking for. Dwight