* Updates to tx3904 peripheral simulations for ECC.

* Updates to tx3904 peripheral simulations for ECC.
Tue Jun  9 12:29:50 1998  Frank Ch. Eigler  <fche@cygnus.com>
	* dv-tx3904cpu.c (deliver_*_interrupt,*_port_event): Set the CAUSE
 	register upon non-zero interrupt event level, clear upon zero
 	event value.
	* dv-tx3904irc.c (*_port_event): Handle deactivated interrupt signal
	by passing zero event value.
	(*_io_{read,write}_buffer): Endianness fixes.
	* dv-tx3904tmr.c (*_io_{read,write}_buffer): Endianness fixes.
	(deliver_*_tick): Reduce sim event interval to 75% of count interval.
	* interp.c (sim_open): Added jmr3904pal board type that adds PAL-based
	serial I/O and timer module at base address 0xFFFF0000.