Re: Not able to boot from SCSI disk on SYM21002 but all other works

Manfred Preussig schrieb:
hello,
I'm a newcomer here from germany so please excuse if something is miss-formulated or bad english.

I have an older 21002 with 53C896 on. It is a two channel SCSI hba with 16 bit SCSI (up to 80 Mb/s) and PCI interface. The system it was in was damaged some time ago so the mb is no longer usable. As I got a new mb from some friend I tried out the other parts and the supply was not correctly functioning but the other parts seems to be o.k. With one restriction: as I tried to boot the new system from the SCSI disk (as I done with old system too) it presents only "PRESS ANY KEY TO REBOOT' (all in capitals as here -I want to make it easier to recognize it- and the only seeable on the whole screen) and stops. Pressing any key reboots up to this point ... and all comes again.

I tried with some linux DVD useable as live systems (in germany -I don't know if this is the some in other countries- a lot of illustrated papers concerning computer themes puts into their product a CD or DVD with a lot of software on it. Some of these contains one -or more- complete linux installation packages -with live system included- belonging to different distributions). I can boot them all if I do it from the DVD writer which is IDE. The DVD-ROM (SCSI) isn't bootable as the disks. Most of the tries it is not not-bootable from beginning but it stops and hangs later on. I found out that the hangs came up if the boot image is a floppy emulation. Possibly there is a link. All SCSI devices can be reached from linux; all partitions -linux or windows- can be read. I tried a dd on the whole disks to see if there is any fault on them but it works all fine.

Starting from here all have to be new-interpreted. I have got from some friend another hba: SYM22801, which is two-channel too, which is 16 bit too and which bases on the 53C875 chip from Symbios Logic. Of course this could work before in another system but here it looks like the same. So it have to be another problem.

As I boot from floppy (which works fine) with a suddenly found old MS-DOS 6.2 boot disk I found out another thing: the system even don't know anything concerning the SCSI system. As I wrote C: (which would change the so-called active drive from the A: from boot to the first MS-DOS-partition to be found) nothing happens ... not correct, an error occurs. There is no C: at all. Of course the windows XP C: is not for DOS since it is with FAT32 formatted (not NTFS since up to some months ago Linux can't use NTFS completely) and DOS don't know anything about FAT32. But I have some other partitions (partly historical reasons but I use for some real old hardware like an eprom writer a DOS installation on the disk too) and some of them are FAT formatted (the older one). Of course there are some longer filenames on them but this don't blocks DOS from using this drive -that's only true for FAT32, not FAT16 with V-FAT (the longer names system). So if any of the drives in the SCSI system could be found this would be enabled as C: and up. If there is no C: there is no drive at all -and this is astonishing.

I had tried to boot from floppy disk with lilo and the SCSI hdd's. Only lilo and the map file on the floppy and the rest from the disk. But lilo stops. This didn't work. Now with this DOS information I think I know the reason:

The BIOS itself needs accesss to drives of course to boot and so on. This is implemented as a lot of routines with a central dispatcher called INT13. The BIOS works in real mode (a simple processor mode) and DOS too. What was easier to do as to use the INT13 from DOS too. And so it does. The Lilo of course boot in real mode too since that's the only mode the processor can do without help from OS (it needs some tables which have to be build in real mode and depends on the OS before it switches up to other modes). So the Lilo uses INT13 too. To dispatch the calls between the different drives the BIOS uses drive numbers a little bit similar to the major device numbers in Linux. Floppies are numbered from 0 up, hdd's from 128 (0x80) up. So if there is any drive in the system this would get the number 0x80 and the next 0x81 and so forth. The lowest numbered drive with some DOS-reachable formatted partitions on will contain C: drive then. If there is no C: this means either there is no disk with DOS-reachable formatted partitions on or there is no disk. Since I know there are such partitions on the disks (and I know from the linux boot tests that they are even there -not deleted or corrupted) the result have to be: there are no disks found. Even drive 0x80 doesn't exist.

Before since the mainboard damage causes some additional problems I thought it is the SCSI BIOS (which has INT13 routines inside too) which doesn't register the drives found on SCSI so there are no INT13 numbers asigned to them. That's seems to be the most plausible and simple suggestion what is happening there. So I wrote the other message here. But now since with another adaptor never inserted in the damaged system this have to be changed.

So the SCSI INT13 routines can not be the reason. The BIOS presents a message that the SCSI BIOS is installed during startup (before boot). This Installation includes the addition of the SCSI INT13 routines to the BIOS INT13 system dispather. So if the SCSI BIOS is installed this additional routines (which of course are needed since the normal BIOS routines knows nothing about how to handle SCSI) are installed too -even if the SCSI BIOS is not damaged but this we don't have to think of now.

The conclusion is: the SCSI BIOS is not damaged, the INT13 works correctly, the ROM BIOS is not damaged (since the damaged board is discarded and changed with another board working fine with Linux from DVD this we can believe I think) I don't know anything I can look for. FIXMBR I tried before but this of course (from setup cd I can boot off) (since there is no parameter) works on drive C: or in detail on the disk C: resides on ... with the same problems mentioned above.

So a problem with the disk I can rule out since Linux can use it and the partitions on it too. So the only problem thinkable on disk are the mbr or the boot sector of the partition. But if I switch active partition (which is normally the sda3 with Lilo on it) to sda4 (the windows XP one) the problem doesn't change. So there is only the mbr code. But in Linux a long time before I saved the mbr code since windows setup tends to write new information there and so I wanted to could go back if I need to do so. This file named sda-mbr (which of course is clear enough don't to think of using the wrong file) I have wrote back to sda at the beginning of the problems.

ROM-BIOS C-MOS-RAM deletion I have done. No change.

The essence is: I don't know what to do. I'm frustrated. I'm desparate. I can't boot windows from DVD (only the setup but this won't help) so all off the data, programs settings and so on on the SCSI disks are lost. Of course I could buy an IDE drive, make partitions there and copy all of it to this drives. But it's a real hard and long-term work and I'm not sure it works for all data since there are some data hidden from normal access (like licences for music for instance). It is a horror. Even more since all seems to work -even in spite of booting. So I have to think it's a kind of simple error. But what?

Any idea?

Manfred

p.s.: Of course I know this now could be an error not related to SCSI. But a IDE drive not bootable added for test seems to work (it stops but at another point and with another message). So it seems to be related to SCSI at all.
.

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