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This is applied 27732 the Vcc pin and is typically 5 volts. If you know the basics though the software is easy enough to follow. Figure 4 shows a screen shot of my programmer with a 4k System 80 ROM image loaded. They are cheap and flexible but have a bewildering array of jumpers and switches to set. The other voltage is the programming voltage Vpp.
Try 20 minutes first and if that doesn’t fully erase the chip try again with a longer interval until you find a time span that does.
In particular make sure the Vpp is correct and that the IC is oriented correctly and in the right position on the IC holder. Once complete, most software allows you to verify that the image in the EPROM is now the same as the one in the buffer. It is not the harmless UV found in disco lights.
Here is one of my efforts regarding the latter. Be sure to check when ordering and make sure you get the UV-erasable version unless you want an OTP of course. Usually these ICs start with either a or a prefix but there may be others. There are a number of programmers on the market.
2532/2732 EPROM Adapter
Modern programmers use menu-based interfaces that are easy to use. A can hold 4k and so on. There will be an icon or menu selection for this. The software that comes with the programmer will manage the burning process. Fig 1 shows my eraser.
These have a “C” between the prefix and size number e. It’s almost completely unreadable. Usually a status bar shows progress.
EPROM Technical Data
There are 8 kilobits in a kilobyte. I had a Willem but it died so my current programmer is a Top out of China fig 3. Once reprogrammed or “burned”they can hold their data for many years. These are inexpensive devices that can be found on eBay. One is the READ voltage. After the prefix is a number such as 16, or 32, 64, etc. Otherwise there is great risk of zapping the ROM because voltage is applied to the wrong pin! It may even check automatically. It seems to work well, although at the time of writing the manual for this Chinese device appears to have been written using an early version of Google Translator!
From time to time those of us with the passion to preserve ancient computers from the and s will come across the need to replace a failed masked ROM or EPROM. The epgom voltage can kill it.
Typically, my eraser will blank a chip in about 20 minutes. The ICs hold code, often an auxiliary program such as an application, utility or game which can be loaded immediately on startup.
If things are OK, you’re done. First rule is to know the kind of EPROMS you want or are likely to want to burn and get a programmer that can handle them. Here is an important piece of advice. Typical values are 25v, 21v or The UV wavelength used is the same as that used for sterilizing equipment. Make sure you know the specs you’re dealing with. This article is just a basic primer.