Looping before changing batch files

I am experimenting a bit for fun I want a matrix-like transition between my call batch1.bat and my call batch2.bat so I have this command

echo off color 0a :start echo %random% %random% %random% %random% %random% %random% %random% %random% %random% %random% %random% %random% %random% %random% goto start call batch2.bat

and I want to set it to loop for 3 seconds before moving on to batch2.bat but I am new and I don't know how.