< running on another computer (the same way they wrote BASIC for the Altair) < Would they have waited to receive a beta unit to test/develop it live afte < months of writing blind code based on IBM's specifications documents? Likely they used a intel MDS800 running asm86 or PLM86. They could run on intel ISB86 systems (multibus 8086 based). the 8086 was introdued in '78 and available in '79 so hardware was not a problem. Heck they could ahve used a Seattle Computers S100 8086 crate. < it to DOS6 code, it seems like the DOS1 boot sector loads both BIO and DO < back-to-back in memory (producing a single image, if you will), and then < jumps to BIO. DOS6, in comparison, the boot sector loads IO, which then < loads DOS. < < Any thoughts? I felt this qualifies as "classic" since the file dates < are May 7, 1982 <g> The monolithic load is an artifact of the CP/m heritage in general and specifically CP/M1.4. It's effect was to make loading drivers difficult. That resulted in later version loading the IO which is more extensable and then using the io to load the DOS. I may add that CP/M2.x put more of the burden in the bios and also seperated the load preocess more. Parallel development. Allison