The history of FPGA#

Learning goals:

  • Know where the FPGAs come from

  • Differentiate FPGAs from PALs, CPLDs and similar predecessors

  • Understand which factors led to the success of FPGAs

Based on the video essay The History of the FPGA: The Ultimate Flex

Exercise 168

What is an FPGA in a single sentence?

Exercise 169

  1. How did the engineers prototype digital circuits before FPGAs?

  2. What are the downsides of these approaches?

Exercise 170

  1. What were first programmable circuits that can be used to implement combinational and sequential logic?

  2. How do they work?

The umbrella term for programmable (or reconfigurable) digital logic components is programmable logic device (PLD). According to Wikipedia the PLDs in increasing complexity are:

  1. Simple programmable logic devices (SPLD)

    1. PAL

    2. PLA

    3. GAL

  2. CPLD

  3. FPGA

Exercise 171

PLA was programmable both on the AND and OR planes. PAL was an alternative design to PLA. What were the differences?

Exercise 172

Burning the fuses is irreversible. Which technology had improved on this?

Exercise 173

One of the pioneers of programmable logic is Altera (bought by Intel). Altera’s first product was EP300. It was a PAL based on EPROM. Then Altera came up with CPLD (complex programmable logic device).

  1. What was the improvement of CPLDs (over PALs)?

  2. Which technological advancements led to these improvements?

Exercise 174

Ross Freeman was the co-founder of Xilinx and invented the first FPGA. Which belief or dream led him to this invention?

Exercise 175

The first FPGA is Xilinx XC2064 (later part of XC2000 family). What was FPGA’s improvement over CPLD?


CPLDs integrate a non-volatile memory, so they are immediately functional after power-up. Typical modern FPGAs have volatile memory (typically SRAM) and need to be configured after power-up. There are also FPGAs based on non-volatile memory like Microchip ProASIC and IGLOO FPGAs, but these do not offer the logic resources that SRAM-based FPGAs offer and are thus only popular in niche applications like aerospace and military.

The (1) instant functionality after power-up and (2) reduced complexity are distinctive features of CPLDs over modern typical FPGAs.

Exercise 176

FPGA and PAL chips were competing with each other back then. What were their differences?

Exercise 177

LUT count and wire length in FPGAs grew exponentially due to Moore’s law and improvements in semiconductor manufacturing (e.g., chemical-mechanical polishing.

What does wire length in an FPGA mean and what is it good for?

Exercise 178

Which business advancements helped to the success of FPGAs?

Exercise 179

  1. The PAL manufacturers depended on third-party EDA software which caused a problem later. Why?

  2. How did Xilinx deal with this problem?

Exercise 180

The author of the essay names the FPGA as the ultimate flex. What could be the reason?

Also interesting#