RISC OS 5.22 bug

If I set the WimpSlot to much above 256Mbytes, start BASIC and call SYS “Font_StringBBox” I sometimes get a fatal error (ERR=0) with corrupted error text but with ERL pointing to the line containing the SYS call. If I set the Wimpslot below 128Mbytes I cannot reproduce this error.

It is worse using the recommended SYS “Font_ScanString” call as that, in the same circumstances, stiffs the machine rather than return an error, requiring a power off.

I am told this is a RISC OS 5.2x bug and not an ARMX6 bug.