Production ROM for the 1702 Family - The Intel 1702 is the world’s first EPROM (Erasable Programmable Read Only Memory). In the early 70’s, before DVD’s, CD’s, hard disks, and even diskettes, programmers had a real challenge in storing data in small computers when they were turned off. RAM (Random Access Memory) chips were great for storing information, but all bits were reset to zero when the power was turned off. At that time, data and programs were stored on ROMs (Read Only Memory) chips that had to be created in chip making factories. If the data or program needed to be changed, a new chip would have to be ordered, which could take months for delivery. EPROM’s were a huge jump in productivity for computer designers. As with many great inventions, the EPROM was an accident. The permanent memory ability of the EPROM was discovered when some standard RAM chips, which should have been reset when the power was turned off, didn’t. Subsequent investigation led to a very useful new semiconductor device. EPROM’s can be programmed electronically to any bit pattern and they will hold those patterns for 30 plus years. However, when strong UV (Ultraviolet) light is shined on the chip, the bits are reset to zero, with no factory involvement at all. Intel’s 1302, 1602, and 1702 devices all used the same chip, which was inscribed with a 1602 designation in the lower right corner. These are 2048 bit EPROMS organized as 256 bits by 8 (a tiny fraction by today’s standards). This 1702 EPROM was manufactured in the early 70’s. This one is a beauty. It has gold legs, a white ceramic case, and a gold top with a quartz window (used to shine UV light to erase the memory). You can easily see the chip and wires. These chips were used in some of the earliest computers that used the Intel 4004, 8008, and 8080 microprocessors.
