Anyone who cares... Using my XOR S-4 S-100 computer I built IBM 3740 disks (SDSS) tonight. I had to replace a cap near the 7812 and one of the 1488 drivers on the CPU I/O card first, to get the system to work, but after that I was all set. 128 bytes 26 sectors per track, ~241K capacity. There were a lot of disk formats back then, I had to double check I was building the right thing as the old systems are flexible yet cryptic. So, should I attempt to build or image disks using the catweasel MK4 as the drive controller I have an actual disk to play with, or image disk. The XOR S-4 system I am using has Mitubishi M2896-63-02U drives, they're 8" DS/DD and the disk controller uses a 1795 FDC chip. The computer with the Catweasel has a Tandon 848. I'll post more details on my site as I make progress with photos. Bill