Hi Frank/Gary in particular. I’m still not clear where to start on figuring out where to start of figuring out why you both cannot boot MSDOS with the ZFDC board and floppies. To get started and to make sure we all have the same starting points I have uploaded the V3.5 version or the ZFDC 28C256 ROM “monitor” for the board. A .pdf file and .zip file containing the source code, .lst and .hex file is there. See bottom of this page: http://s100computers.com/My%20System%20Pages/ZFDC%20Board/ZFDC.htm MOST CURRENT ZFDC.Z80 (V3.5 8/15/2014) MOST CURRENT SOURCE CODE FOR ABOVE FILES (8/15/2014) Can you confirm that is what you are using. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Frank Schieschke Hello John, -- |