	With the `XBUF' mod, not all device drivers (e.g. hp.c)
will compile - the only block-device drivers which have been
tried with this mod are RK05, RL01, RL02  SI/CDC  9762,TM-11 and TC-11.
	The RL driver has been re-written to cope with both RL01
and RL02 drives, at the same time checks have been put in for
off-line and write protected volumes. These checks have also
been put into the RK and TM drivers.
	The file 'rk.boston' is a modified V6 boston Childrens
Museum driver, which will handle overlapped seeks on multiple
rk drives. It lacks however the 'open' checks of the standard
driver.
