From: utzoo!decvax!harpo!zeppo!whuxk!whonxa!netnews Newsgroups: net.micro Title: Re: CP/M BDOS Article-I.D.: whonxa.130 Posted: Fri Sep 10 08:25:28 1982 Received: Sat Sep 11 01:27:42 1982 References: sri-unix.3178 I dont know anything about Osborne CP/M, but there are obvious answers to all of your questions concerning standard CP/M. I would recommend the Digital Research Guide to CP/M Interface with the proviso that you COULD have to review the addresses for your particular implementation. To answer your major questions: CP/M uses only the default DMA address and FCB, but allows an interface to change either. If changed, any disk access will use the current DMA address (presuming that you dont restart the system) and you (the user) specifies the FCB address in the BDOS call. John Beal either at the address shown in the header (except this machine will be down all next week) or whuxg!beal or Bell Labs Whippany NJ 201-386-5060