Midwest Scientific Instruments 6800

On Monday (08/01/2016 at 08:24PM -0700), Brad H wrote: Yup. PERCOM LFD-400. Two of the EPROMs on there make up their little "DOS". It's pretty crude in the modern sense in that you deal with everything by tracks and sectors and the MINIDOS+ extension in the second PROM adds simple named files but otherwise you are just saving and loading memory images to tracks and sectors on a floppy. Nothing handles recovery of deleted space or allows for non-contiguous blocks within a file. They were just getting started with floppies around 1977 when that board was first available. The entry point to this DOS was usually at $C000. So, if you can figure out how to get your monitor to jump to an address, that's where you'd want to go to get the DOS executing. I don't know what the third PROM would be for on your board. It might be driver extensions/support for another operating system or could be really anything. In my system, I put a Diablo daisy wheel printer driver into that third PROM. The PROMs are at $C000, $C400 and $C800. With MIKBUG monitor, to jump to $C000, you would put that address into RAM locations $A048 and $A049. $A048=$C0, $A049=$00 and then use the "G" function to GO to that address. With SWTBUG, the "Z" function jumped to $C000 directly. Maybe your WEEBUG has "G" or "Z"?? With both MIKBUG and SWTBUG, you could examine and change memory with "M", *M A048 A048 C0<cr> A049 00<cr> A04A 55<space><cr> * Yes. I haven't heard of WEEBUG until your posting. And see nothing after some web searching other than this old post, http://www.old-computers.com/museum/computer.asp?c=732&st=1 Where a guy named "Dana Peterson (Arizon)" says he was the designer of the MSI 6800. Maybe he can be tracked down? Good luck. It's a nice system. Chris -- Chris Elmquist