FPGA

FPGA stands for field-programmable gate array. It is an ASIC that can reprogrammed after it is manufactured — a programmable logic device. Device manufacturers include Xilinx (http://www.xilinx.com/), Altera (http://www.altera.com/), Lattice (http://www.latticesemi.com/), Actel (http://www.actel.com/), Agere (http://www.lucent.com/micro/netcom/orca/index.html) (formerly Lucent), Cypress (http://www.cypress.com/cypress/prodgate/prog.html), Atmel (http://www.atmel.com/) and QuickLogic (http://www.quicklogic.com/).

Many modern FPGAs have the ability to be reprogrammed at 'run time', and this is leading to the idea of reconfigurable computing or reconfigurable systems - CPUs that reconfigure themselves to suit the task at hand.

Basic Process Technology Types

• SRAM - based on static memory technology. In-system programmable and re-programmable. Requires external boot devices. Usually CMOS.
• Anti-fuse - One-time programmable. CMOS.
• EPROM - Electrically Programmable Read-Only Memory technology. Usually one-time programmable in production because of plastic packaging. Windowed devices can be erased with ultraviolet (UV) light. CMOS.
• EEPROM - Electrically Eraseable Programmable Read-Only Memory technology. Can be erased, even in plastic packages. Some, but not all, EEPROM devices can be in-system programmed. CMOS.
• FLASH - Flash-erase EPROM technology. Can be erased, even in plastic packages. Some, but not all, FLASH devices can be in-system programmed. Usually, a FLASH cell is smaller than an equivalent EEPROM cell and is therefore less expensive to manufacture. CMOS.
• Fuse - One-time programmable. Bipolar.

Links

• FAQ from Optimagic (http://www.optimagic.com/faq.html)
• Programmable Logic Jump Station (http://www.optimagic.com/) - Comprehensive links to FPGA, CPLD, and reconfigurable computing sites, from Optimagic.