OK, I now understand what's going on - I put a spare drive onto the secondary IDE bus and the Aos CD boots fine. With only the CD-ROM drive on the secondary bus, the IDE driver fails to reset (see previous trace, compared with working trace below) and IDE3 is not recognized. Any chance of fixing this? Note that exactly the same problem happens with Native - I hadn't tried mounting the CD before, but it only works if a hard drive is added to the bus. Presumably the same driver? Also, the old drive is recognized twice (it IS old, and I checked the jumpers are set correctly). Is this also something which could be fixed? See why Wirth built his own hardware? :) Aos 03.01.2003 Single-processor IDE0..1: 14 000001F0 000003F6 reset ok IDE2..3: 15 00000170 00000376 reset ok <--- that's better! IDE3: no reset IDE0: 520MB, 1057*16*63, ST3660A IDE1: 520MB, 1057*16*63, ST3660A IDE2: 38931MB, 16383*16*63, (79098*16*63), LBA, SAMSUNG SV4084H, ver 6.23 IDE3: packet cd-rom device, removable, IDE-CD ReWritable-2x2x6 IDE0..1: Bus-master enabled IDE2..3: Bus-master enabled SCSI - 1.0 / prk AosAdaptec7 - 0.41 / prk AosDiskFS: Index not found on RAM0 AosDiskFS: Scanning RAM0... marking 0 files AosDiskFS: 31992K of 32000K available on RAM0 AosDiskVolumes: IDE0ATA: early D0 50 invalid partition AosDiskVolumes: IDE1ATA: Status ctrl=000001F0 drv=1 hd=15 sec=0 cyl=0 err=04 st0 error 2817 AosDiskVolumes: IDE2ATA: early D0 50 invalid partition AosDiskVolumes: IDE3#0 {P0 AosDisplayLinear: GlobalSetCacheProperties = 2304} UsbUhci: Initialised USB UHCI controller at base 0D400H, Irq: 9 Default font installedManager.New finished Disp.format = 2 {P0 Bottom up... And so on. Paul Reed