Frank it’s a long time since I was there last! So I inserted a V2 version of our 80286 card in the system using the onboard monitor (V10.33). The CPU was 8MHz, with 1 wait state for ROM & I/O. MSDOS V4.01 booted up fine with the monitor C command. So I’m not sure what the problem is. Do you have the IDE board, and can you boot MSDOS on that board and then see the floppy within MSDOS itself. The fact that you are able to run correctly all the PC-BIOS ZFDCDIAG commands suggests to me there is a problem with your MSDOS software on the disk. Are you absolutely sure you can read the sectors correctly and that the sector information you are getting is the same as that you get if you read that same sector on a PC under MSDOS using the Debug disk read sector command. The “3DH” error returned by the ZFDC board is a timeout error. You sent a command to the ZFDC board which it could not complete in a reasonable time. You may have to copy your monitor to RAM and single step through the BIOS sections or modify it displaying outputs on the screen as you go along. Alternatively use the serial port debug option. The way the monitor is currently configured it’s expecting a standard 1.44M 3.5” floppy in drive #3 of the ZFDC for MSDOS. Does the 3.5” drive LED light up on boot. John From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Frank Schieschke Hello John, -- |