In the seventies and eighties, various programmable logic devices were developed. These included the Field Programmable Gate Array( FPGA), various versions of the Programmable Logic Devices( PLD), the Programmable Array Logic( PAL) and the Generic Array Logic (GAL).
The Generic Array Logic (GAL) has the same logical properties as the Programmable Array Logic (PAL) with the difference that it can be erased and reprogrammed. The GAL technique is particularly suitable for prototyping, since it is reprogrammable, bugs detected during this development phase can be quickly fixed. For programming and reprogramming, GALs used a PAL programmer or in-circuit programming.