Fix UART hang in toy Verilator simulator
Fix UART hang in toy Verilator simulator

RGD2/swapforth,GuzTech/swapforth,zuloloxi/swapforth,uho/swapforth,jamesbowman/swapforth,zuloloxi/swapforth,jamesbowman/swapforth,zuloloxi/swapforth,RGD2/swapforth,jamesbowman/swapforth,RGD2/swapforth,jamesbowman/swapforth,RGD2/swapforth,GuzTech/swapforth,uho/swapforth,GuzTech/swapforth,GuzTech/swapforth,uho/swapforth,uho/swapforth,zuloloxi/swapforth