I wanted to store the date and time on the IBM XT 5160, and thus i stumbled upon a great project on Tindie.
For a small card it’s a fun thing to solder together and get working. But it needs some explaination if you want to use it on a XT.
Take a look onto the github page of spark2k06 the creator of the card.
The software i use you can find here: RTC.zip
I’m using the following in the Autoexec.bat:
c:\rtc\get_rtc 576
Where as the 576 stands for: port 240h