The most important chip in commodore 64 computer is the PLA chip. When this chip is broken, nothing will work and most certainly you will get a black screen after you try to turn it on.
FPGA's and CPLD's are certainly very cool devices. It is possible to create you own logical circuits and emulate real hardware chips on the lowest level. For this test project we will use Alera CPLD which is also known as MAX3000A and it's full code is ALTERA EPM3064ATC44-10.