A Brief History of Programmable Logic

You may have wondered, what's all this programmable logic stuff about anyway? To help answer that question, let's look at a history of programmable logic devices to give us some perspective on programmable logic devices, PLDs in general, and field programmable gate arrays, or FPGAs in particular.
FPGAs are a subset programmable logic devices. Here's a brief history of the development of programmable logic devices. The first programmable logic device was a PROM or a Programmable Read Only Memory. It was invented in 1956 but not commercially available until 1969. Followed in quickly by EPROMs are Erasable Programmable Read Only Memory in 1971. And then, PLAs, Programmable Logic Arrays in 1975. And PALs, Programmable Array Logic in 1978. We'll explain the difference between these in this video. The desire to have programmable hardware has been in existence ever since the very beginning of digital hardware. We can realize any logic equation to level some of product format. Let us denote the AND logic in a format which is easy for us to illustrate the AND and OR planes.
To the left is a traditional notion for a three input end gate. To the right is the notion that we will adopt for two level programmable logic blocks. A dot for hardwired, an x programmable link and a blank for no connect. As you can see, programmable logic is as easy as ABC. In fact, the first programmable logic is a PROM. The PROM has a fixed AND plane or product terms which is the address decoding logic. The OR plain or the sum terms is programmable through the change of memory contents. This is an eight by four PROM depicted here. Using this, we could implement the logic function output one equals ABC by storing in the first column of the PROM the eight bit word, 0 0 0 0 0 0 0 0 0 0 1. Then, only when A, B and C are all ones where the output, output one be a one. In the same way, we can make the OR plane fixed and make the AND plain programmable.
The following figure illustrates the general approach of a PAL which has a fixed OR plane but has a programmable AND plane. PAL devices are very popular and they're still used in many designs, with common part numbers like 22V10 or 16R8. Further development led to CPLDs, which were devices with multiple PALs in the same package with registered outputs and interconnecting programmable fabric.
The FPGA industry sprouted from the programmable read-only memory (PROMs) and other programmable logic devices (PLDs). In the 1980s, the Naval Service Warfare Center funded an experiment proposed by Steve Castleman to develop a computer that would implement 600000 reprogrammable gates.
The EP300 which featured a quartz window in the package that allowed users to shine an ultraviolet lamp on the dye to erase the EPROM cells that held the device configuration. For many years, Altera touted the benefits of the CPLDs architecture over that of FPGAs, but later relented and began making FPGAs as well. Xilinx co-founders, Ross Freeman and Bernard von der Schmidt, invented the first commercially viable fill programmable gate array in 1985, the XC2064. The XC2064 have programmable gates, programmable interconnects between the gates and therefore, the beginnings of a new technology and a new market. The XC2064 had 64 Configurable Logic Blocks or CLBs with two three-input lookup tables or LUTS which are still important in FPGA architecture today. More than 20 years later, Freeman was entered into the National Inventors Hall of Fame for this invention. In the early 1990s, FPGAs were primary used in telecommunications and networking. By the end of the decade, FPGAs found their way into consumer, automotive and industrial applications.
Programmable logic is just one part of the pantheon of digital logic devices. An ASSP or Application-Specific Standard Product is a semiconductor device integrated circuit product that is dedicated to a specific application market and sold to more than one user and thus standard. ASSP is marketed to multiple customers just as a general purpose product is but it's to a smaller number of customers since this is for a specific application.
Field Programmable Gate Arrays (FPGAs) are programmable logic devices made of gates, registers, and routing wires connected together in a pattern that can be programmed after the device is deployed. Creating the interconnecting pattern is the heart of FPGA design. Programmable Logic Devices (PLDs) include simple PLDs like PROMs and PALs, complex PLDs (CPLDs), FPGAs, and SoC FPGAs. PLDs are a subset of all logical devices and FPGAs are a subset of PLDs. FPGAs compete with Application-Specific Integrated Circuits, or ASICs, and Application-Specific Standard Products, or ASSPs, successfully displacing them in many applications. When it comes to digital devices, FPGAs appear to be the future