I think I am now OK. I cannot load Knoppix. It stalled when trying to set up graphics. My version does not appear to allow running it from the command line. The message says it is reading from Xorg/configure but the there is no activity on the hard drive or the cd.

I tried Wheezy live but of course could not get into superuser mode. Mount showed all drives as rw. Unfortunately this left me with /var full and without being able to write to any drive I can't empty it. I have done a full install of Debian 9 and mount shows all drives rw. I will have a lot of work setting everything up again so at the moment I can't access my 20gb backup drive but I can access driveb which also has a backup. I must have done something wrong when I partitioned the drive during the first installation.

I had a lot of trouble when I first tried to install 9 when it became available. It stalled creating the bootloader. After a lot of research I looked at the bios. I have Gigabyte and I found that it had been changed to uefi (is that right) and I had to reset it to legacy. The boot order gets changed too. I have had better bios systems but that's what came with the computer. It's offered as an empty machine and supplied by PB Technologies. I don't know if they exist outside NZ.

Thanks for all your help.

Alaric

I don't use UEFI or GPT.

if /dev/sda PC will never have windows 8 or higher on it, its safe to stay with MBR and the 4 maximum primary partitions
or 3 primary one extended and quite a few logical.

Personally I see no benefit in having so many mount points but is just me.

as I have no skills with UEFI I suggest you mark this one as solved,
research the pro and cons of going to a GPT partition system and if still unsure
create a new post asking for help on that issue.