The serial terminals did that as well and you couldn't unconfiure it on early sun4 prom revisions. You could get around it by using a rs232 breakout box with a

The serial terminals did that as well and you couldn't unconfiure it on early sun4 prom revisions. You could get around it by using a rs232 breakout box with a resistor soldered in it and then screw that box to the back of the unit. That was standard practice. I remember when sysadmins were good with a soldering iron...