The DEL key will get you into the AMI BIOS. At least I assume it is the DEL key. It's the top right-hand key on my AZERTY keyboard marked Suppr.
Should you need it the default Wyse password of Fireport works.
In the opening screen it shows the BIOS version as THIN Client R1.05. In the linux dmesg output I find the date: 03/25/2008.
The BIOS is fairly conventional with a limited range of options. In the Boot screen you have the option of setting the Boot Devices in order of priority. In my simple check it looks like the devices that get listed for you to choose from are anything the BIOS happens to find that it thinks it can boot from. To start with this was:
1st Boot Device [Network:VIA BootAg]
2nd Boot Device [HDD: 512MB ATA Fla]
If you plug in a USB pen drive and reboot then the options become:
1st Boot Device [Network:VIA BootAg]
2nd Boot Device [HDD: 512MB ATA Fla]
3rd Boot Device [USB:USB2.0 FlashDi]
As usual the +/- keys let you reorder the list.
The X90 runs XPe. On the Wyse website under 'Downloads for X90 / X90e' I found: 'Windows XPe WFR2 V5.01 Build 617 for X90\X90e, (387.28 MB) 09-Feb-2009'.
My initial attempts to install it on my X90, whilst apparently completing successfully, always resulted in a 'Missing Operating System' whenever I tried to boot from the flash drive.
Later I had another look at it and got there but by a rather roundabout route. I don't know if it can be shortened. So here's one way of installing a fresh copy of XPe. The preparatory work I do on a PC so, when talking about paths in that environment (as opposed to Linux) I use a '\' character.
To get round this problem I also install Tiny Core as (a) it is an easy way of installing the syslinux boot loader to replace the not-working Grub boot loader, and (b) We'll also be using Tiny Core in the final step.
LABEL Wyse MENU LABEL Wyse X90 re-flash TEXT HELP Wyse XPe flash of X90. ENDTEXT KERNEL /kernel/vmlinuz INITRD /initrd/initrd.pxe APPEND rw root=/dev/ram ramdisk_size=131072 vga=785 waitusb=5 splash=silent ide_generic.probe_mask=0x03
dd if=/mnt/sdb1/Image/par1.raw of=/dev/sda2
You can speed up the process if you want by increasing the block size.
A bit of a rigmarole but it gets you there.