I would like to close this old thread with my last try.
A SD card has to be checked if it is bootable? (after installation of extlinux and different distros on it)
- find a SD card adapter to USB
- go to your old PC; your PC has no bootable USB?
No problem, install plop on it.. see http://www.plop.at/en/bootmanager.html
and choose the plpbt.bin for the PC with PCMIA cards (like mine).
- boot your pc
- choose the grub menu "plop bootloader" (I made before)
- choose the USB boot of plop after it detected you putted your SD card on the USB adapter in the PCMIA card (USB 2.0)
- then it boots.. in the extlinux menu of the bootloader of the SD card (with tinycorelinux, knoppix, slitaz, partegmagic, puppylinux, HWtest, memtest. warrylinux..)
- then choose tinycorelinux
- then open firefox.. and write here.
So, my old machine, year 1997, without USB boot section in the BIOS, is booting from an SD card on an USB-adapter.
I am happy.