I can't identify my bike... Serial number ACM05F006119 20 inch bmx?
Serial number is quite useless, but still, a bike with a similar serial number can be seen here:
https://bikeindex.org/bikes/633505

Serial number may be similar by chance, or it may come from the same factory.
If your bike is similar to the bike depicted there, you may have got a bmx branded MCS, unlikely it is from 80s, likely to be some mass produced aluminium thing similar to a bicycle. The bike in the picture above is from 2005.
Check this models gallery:
https://bmxmuseum.com/bikes/mcs/
to see if yours is similar to any of them.