ZMON in the 4FDC and later 16FDC were very Z80 in that they use the funky bulk input instruction (INIR?) to read tracks from disk. They also swap register sets in lieu of using a stack. Both worthless on the 8080A. The monitor was extremely simple (even simpler than the 2K z80 monitor I wrote) the only interesting bit was that it could read/write a track on the disk and manipulate bits in memory. I used it to bootstrap my Cromemco BIOS by having ZMON write the "media" type byte on the disk and then after loading CP/M doing a SAVE and having the rest of the system installed. --Chuck At 07:30 PM 7/22/99 -0400, you wrote:

At 07:30 PM 7/22/99 -0400, Bill wrote: Yes I have used the 1k "RDOS" monitor, one thing that made it useful was the source printed in their brown booklet. Back when, I modified it to use a Vector Graphics flashwriter. You might look for earlier Cromemco monitors that could use a 8080A. (Like with a 8k Bytesaver). If you aren't using a disk, the 3 most useful cammands are display memory, substitute memory, and jump to a location. I don't remember if any of these in the RDOS monitor would work with a 8080, but they aren't too difficult to program. That monitor source is how I "got my feet wet" with Z-80 assembly. I also have Cromemco "Control basic" somewhere in 3 2708's, but could not get it to run several years ago, either with a TUART or fixed serial port. (bit rot?) -Dave