IBM manual MaxLoader User’s Guide

MaxLoader User’s Guide

NOTE: Erasing EPROMs. In order to clear data in an EPROM, the chip should be exposed to a short wave UV (Ultra violet) light. Most erasers require between 5 and 30 minutes erasing an EPROM. Some types of chips take longer to erase than others. An EPROM based part (a PLD or Microcontroller) with a security bit feature is designed so that the security address is typically the last bit to be erased. If the window of a chip is not clear, try cleaning the window with alcohol or a solvent. Erase chips if the chips are exposed to sunlight and fluorescent light for months or years; your chips can be erased. You should cover the window of the programmed chips with an opaque label to make the data permanent. Some EPROM based parts can't be erased because they do not have a window. These chips are called one time programmable (OTP) EPROMs.

An EPROM has a quartz window located on the chip just above the die. An EPROM is erased by exposing it to high-frequency ultra-violet light waves. Erasing an EPROM usually takes from 15-20 minutes, but may be shorter or longer, depending on the device. Many manufacturers make EPROM erasers. If you wish to purchase an eraser, call EE TOOLS at 408-263-2221, sales@eetools.com. When an EPROM is not being erased, the window may be covered with an opaque label. Sometimes (over a period of years) an EPROM will start to erase due to the level fluorescent light in the room. Direct exposure to sunlight also has this effect and happens much more rapidly and commonly.

NOTE: In order to decide if the device is blank, the user should read the target device. If the buffer is filled with all FFs or 00s, the device is most likely in an erased or unprogrammed state; otherwise, the device is not erased.

CAUTION: Some devices such as Philips P98C52 can pass the BLANK

CHECK routine after they are secured even though they are not blank.

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