QBasic source code

dataport = &H378
OUT dataport, 0
SLEEP (1)
OUT dataport, 1
SLEEP (1)

Notes

This program was written in QBasic 4 , I believe . In QBasic you use the OUT function to send a value out of the specified port . In the above example the port is &H378 and we send a 0 ( led is switched off ) then we delay , switch the led on and then delay again .

Download

ledflash1.bas