It's always been an option to use shielding rather than rad-hard chips or in combination. RCA's SCP-234 aerospace computer weighed 7.9 pounds, plus 3 pounds of lead sheets to protect the RAM and ROM. The Galileo probe used sheets of tungsten to protect the probe relay receiver processor, while the Galileo plasma instrument used tantalum shielding. (I was just doing some research on radiation shielding.)