I'm working on writing a program for CP/M 2.2, and would like to make it stay 'resident' in the system memory. Is there any way I can locate to bottom of the CCP so I don't overwrite it, without doing it at compile time? I'm planning on using only Z-80 based systems (so I can use an offset-based jump) so I should be able to pretty easily make the code re-locatable. All I need to do is be able to figure out where the CCP is so I don't overwrite it. Alternatively, would it be a better idea to write something that loads its own replacement CCP under it, and overloads the old CCP just under the BDOS? I would probably need to intercept the 'JMP WBOOT' and 'JMP BDOS' vectors at address 0 and 5, and keep the old BIOS from overwriting my resident program. Or, would it be better to just modify and re-compile the BIOS for each machine I want to run this on (most of the code would probably remain the same...)? What I'm looking to do is provide a (small) SLIP or PPP based TCP/IP stack for a machine that will stay resident and can be used by CP/M 2.2 [or perhaps MP/M II] user programs. Thanks for any suggestions. -- Pat