written 5.6 years ago by |
Like so many names in the rapidly evolving field of computer technology, names for PLDs are somewhat confusing. Originally, in the 1970s, PLDs consisted of programmable AND arrays and programmable OR arrays and were known as programmable logic arrays or PLAs. In the mid-1970s, a company named AMD developed PLDs that instead had OR gates with fixed rather than programmable inputs and the other PLD figures and referred to such devices as programmable array logic or PALs.
PALs were originally fuse-based and hence one time-programmable. A company named Lattice Semiconductor Corporation developed a PLD using a memory based programming approach rather than fuses, resulting in reprogrammability and referred to such devices as generic array logic or GAL. As PLDs became more complex, PLDs based om PAL or GAL architectures became known as simple PLDs or SPLDs to contrast them with the more complex PLD varieties.
Today, numerous companies manufacture SPLDs and often state that their SPLD architecture is based on PAL or PAL/GAL architectures, with the distinction between PAL and GAL not seemingly relevant in that context. SPLDs typically support tens of logic gates to hundreds of logic gates.