Folks, thanks for your suggestions. I found that:-
/lib/modules/2.4.18-rmk7-pxa3-embedix/kernel/drivers/block/sharp_mmcsd_m.o
(without .rom in the path) also gave a Read-only file system error.
So I tried the remount,rw and then copied the file to:-
/lib/modules.rom/2.4.18-rmk7-pxa3-embedix/kernel/drivers/block/sharp_mmcsd_m.o
which gave no errors. Then ran the SDHC IPK which also ran without errors (I was lazy and used the GUI package manager) so presumably I had chosen the correct file location.
The old 256MB SD is still recognised seemingly without any problems, but the 32GB card is giving me a headache. After fun & games trying to backup the old card onto the new and the new 32GB card not being recognised, I suddenly realised it was formatted to FAT32. Nil desperandum, I thought! I just went to the
OESF SD And CF FAQ and formatted it. No, this doesn't seem to work - gives an error about the size of the card! OK, I'll do it on my PC - eventually (finger &/or brain trouble!) However, now it's FAT16 but still not working correctly. Sometimes it sits there saying "Updating Information", sometimes it doesn't. But it always seems to lock up the Zaurus.
Of course, I may have a duff SD card - it is an Ebay special after all! Also, I note the comment in the FAQ that SD cards work fine so long as the filesystem is left alone. I'm not beaten yet but I've got other stuff to do. I'll let you know how I get on.
Thanks again. All for now,
Richard