PLD：
A programmable logic device is an electronic componet used to build reconfigurable digital circuits. Unlike integrated circuits(IC) which conist of logic gates and have a fixed function, a PLD has an undefined function at the time of manufacture. Before the PLD can be used in a circuit it must be programmed (reconfigured) by using a specialized program.
Early programmable logic:
1969-XC157(Motorola), a mask-programmable gate array with 12 gates and 30 uncommitted input/output pins.
1970-TI developed a mask-programmable IC based on the IBM read-only memory associative memory or ROAM.--TMS2000(17inputs and 18 outputs with 8 JK flip flop)
1971-General Electric Company was developing a programmable logic device based on the new PROM technology.
1973-DM7575(National Semiconductor)----with no memory registers with 14 inputs and 8 outputs.
1974-MMI(Monolithic Memories)
PLA:
PAL:
GALs:
CPLDs:
FPGAs:
How PLDs retain their configuration:
A PLD is a combination of a logic device and a memory device.
The memory is used to store the pattern that was given to the chip during programming. Most of the methods for storing data in an integrated circuit have been adapted for use in PLDs.
These include:Silicon antifuses(反熔丝)、SRAM、EPROM\EEPROM、Flash memory
PLD programming languages:
JEDEC files
HDLs
VHDL、Verilog
PALASM、ABEL、CPUL