Programmable Logic/Programmable Hardware

This page is going to discuss what exactly programmable hardware is.

VLSI

VLSI stands for "Very-Large-Scale Integration", and is the term for a number of different chip architectures that are integrated (many components on a single chip), and are usable for a variety of different purposes. Some more modern chips are referred to as ULSI (U = "Ultra"), but VLSI and ULSI are essentially the same thing.

VLSI (Very Large Scale Integration) refers to integrated circuits with over approximately one hundred thousand transistors. Currently chips with many millions of transistors are sometimes referred to as ULSI (Ultra Large Scale Integration), however the complexity of the designs are approximately the same as VLSI.

Basic process technology types

Name	Description
Antifuse	One-time programmable. CMOS.
EEPROM	Electrically Erasable Programmable Read-Only Memory technology. Can be erased, even in plastic packages. Some, but not all, EEPROM devices can be in-system programmed. CMOS.
EPROM	Erasable 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.
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.
SRAM	based on static memory technology. In-system programmable and re-programmable. Requires external boot devices. CMOS.