This sale is for the four inch National Semiconductor 2716 EPROM wafer with case pictured and the matching chip. The chip has a 1981 date code so I assume the wafer was made within a year or two of that date. National built a four inch fab in 1976. Four inch silicon was state of the art at that time.

A small window in time
The Erasable Programmable Read Only Memory (EPROM) was a major innovation that came about in the 1970s. The 1702  was one of the first EPROM types at 256x8 bits. It was soon followed by the 2704 (512x8 bits), the 2708 (1Kx8 bits), the 2716 (2kx8 bits), etc.  A huge step above ROM (Read Only Memory), these EPROMs were electrically programmable and could be easily erased by a few minutes of exposure to ultraviolet light.

As memory manufacturing technology progressed very rapidly, each device lasted only a short time before it was made obsolete by the next larger device. This is one reason why the smaller sizes are becoming increasingly rare. Another reason is that many older chips contained pure 24k gold bonding wires and some were also gold plated on the outside of the packages. This made them very attractive to gold recyclers.

EPROMs eventually went to several megabits in size before fading into history as more advanced EEPROM (Electrically Erasable Programmable Read Only Memory) and more dense FLASH (large block erasable) memory took over the non-volatile memory market. 


Photos were taken under ordinary white room lighting.

See many other tech collectibles in my ebay store and thanks for looking!