I setup my conner hd as primary and quantum traiblazer 850mb with ontrack ddo as secondary. Jumpers on both dirves set as primary and slave respectively. CMOS setup acoordingly and can autodetect both disks but when in dos mode i get invalid disk for D: as well as in win 3.11 in file manager D drive is not shown. But when i reverse them as both can be seen. Can anyone help please?

Hi, Seems you had settings right. Leaves trial and error method. Anyway, by reversing, I assume you changed Master and Slave drive jumpers and also the position on ribbon cable (master on end and slave in middle). Try to remove jumpers entirely from one or the other or both. And also try any cable select, slave, and master combinations you can think of (keep track). If all attempts fail, do you have the option of putting the Quantum on secondary IDE cable?

Have you formatted the secondary disk?

The overlay (ONTRACT) on the drive prevents it from being seen unless it is set as boot drive. If your motherboard supports the full drive remove the overlay fdisk and format it, If not then you'll have to use it as your boot drive. If you have info you don't want to lose go to QUANTUM and see what their current overlay program can do about removing the overlay without losing info. HTH james

1. I think I must connect the Quantum as slave at the MIDDLE of the ribbon cable and my primary Conner a the end to get it to work. 2. But I still don't understand why even if my AMB bios can autodetect the quantum's full capacity of 850mb it will not boot as a primary if the Ontrack DDO is not installed and throws out a "I/O disk error" message. Any thoughts?

When the ontrack is installed it controls the disk function. If you remove the overlay and fdisk and format then the motherboard controls the disk function. HOWEVER if you look inside your computer the disks are likely attached through a controller card and not through the motherboard. I have run into many 486's that the motherboard BIOS would recognize the full disk size but the onboard controller card would not. That is possibly your problem. Simplest solution if you have all your necessary disks for a reinstall would be to remove the overlay and see if your computer will utilize the full disk without the overlay. Some will, Some won't. Make sure you have good backups before doing this as you could lose all stored info. James