Walk Through the Literal Erase Procedure Pull the Chip Run the Lamp

# Walk Through the Literal Erase Procedure: Pull the Chip, Run the Lamp

## 5. What Erasing an EPROM Actually Required, Step by Step

Erasing a programmed EPROM was a physical, out-of-system procedure, not a software command. An engineer had to power down the target system, physically remove the EPROM from its socket, peel back the opaque label covering its quartz window, and place the bare chip under a dedicated ultraviolet erasing lamp — a small benchtop box built for exactly this purpose — for a period typically quoted at around twenty to thirty minutes, depending on the specific part and how fresh the UV bulb was. The exposure erased the entire die at once: there was no way to target individual bytes or words for erasure, only the whole array. Once erased, the chip had to be reprogrammed, in a separate device, before being reinserted into the target system and the system powered back up. A single erase-reprogram-reinsert cycle routinely took the better part of an hour once lamp warm-up and programmer setup were included, and that hour happened with the target system offline.