Hi guys , hope all is well with everyone. So i just started to learn about ICs that convert a BCD nicely into a 7 segment display . I have learnt about the 4511 and 7447. the 4511 is cmos. when i looked at the truth table for the 7447 IC i found that everywhere the LEDs should be "high" they are on "low". It seems that this IC does exactly the opposite of what you would want it to do. I am sure the guys who made this IC knew what they were doing, but my question is why are the outputs exactly opposite of what you would expect. For example here is the table to display the number 1.
Decimal LT RBI BI/RBO D C B A a b c d e f g
1 H X H L L L H H L L H H H H
Decimal LT RBI BI/RBO D C B A a b c d e f g
1 H X H L L L H H L L H H H H