Complex Programmable Logic Device It is a non-volatile hardware chip that allows for one time (or EEPROM-style) gate programming to implement logic in a lower up-front cost solution than an ASIC and a cheaper and "instant-on" capability that FPGAs lack. They tend to operate in the megahertz range, from around 10Mhz-200Mhz depending on the chip. The prices for CPLDs vary widely, I've seen some in the same series cost down near $5 and up to $100. The more expensive ones typically have military specs or other hardening. https://en.wikipedia.org/wiki/CPLD https://github.com/mikeroyal/CPLD-Guide https://hardwarebee.com/introduction-to-cpld/ https://www.intel.com/content/www/us/en/products/details/fpga/development-kits/max/v-cpld.html # Atmel/Microchip CPLDs Microchip sells a CPLD - the [ATF2500C](https://www.microchip.com/en-us/products/fpgas-and-plds/spld-cplds) - that houses 2,500 logic gates. This is their highest-capacity offering. This is not a lot really, but it should be enough to implement a [[6502]] instruction set if one is careful. It uses 5V communication, with a tolerance of `-2`-`+7`V. And typical draw is around 80mA of power but can peak at 110mA. If I am reading the [data sheet](https://ww1.microchip.com/downloads/en/DeviceDoc/doc0777.pdf) right, this family of chips has a maximum ideal clock speed of 71Mhz as its internal PWM clock period cannot go below 14ns. But I think the actual clocks are limited to 40-52Mhz depending on the exact chip. That would be blazing fast for a 6502 (which capped out at 3Mhz) and the clock speed is on par with mid-90s CPUs (even though the number of logic gates is much lower). The ATF2500C-20KM (SMD) and ATF2500C-20GM (DIP) are rated for miliary temperature range. One step down from that is industrial, and then finally commercial. | Variant | Package | Temp Range | Availability | Cost | | ------- | ----------- | ---------- | ----------------- | ------- | | 15JC | PLCC | 0-70 | | | | 15JI | PLCC | -40-85 | | | | 20JC | PLCC | 0-70 | | | | 20PC | PDIP | 0-70 | Discontinued/Ebay | $8 | | 20JI | PLCC | -40-85 | | | | 20PI | PDIP | -40-85 | Discontinued | | | 20KM | Cer JLCC | -55-125 | Limited | $95 | | 20GM | Cer DIP | -55-125 | | | | 15JU | PLCC (RoHS) | -40-85 | | | | 20PU | PDIP (RoHS) | -40-85 | Limited/Ebay | $10/$16 | | | | | | |