For the information, I'm using a WDC31000 1 Giga disk (2100 cylinders, 16 headers, 63 sectors/track). I've got msdos on Cyl 0-1021, and BSD on 1023 to 2098. Oh! The boot block won't work right if the file system blocks containing the kernel are past cylinder 1023. This is due to a limitation in the old BIOS interface.