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It’s almost completely unreadable.
If things are OK, you’re done. Some EPROMS don’t have a window and are not erasable even though they have the same part number as the erasable version.
EPROMS , , , , , , ,
Usually these ICs start with either a or a prefix but there may be others. These are inexpensive devices that can be found on eBay.
There are 8 kilobits in a kilobyte.
It is not the harmless UV found in disco lights. 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. Often the pin-outs of the mask ROM will be different to the EPROM and some kind of “adapter” needs to be made to switch the pins around or the board circuitry altered.
Here is one of my efforts regarding the latter.
The incorrect voltage can kill it. The other voltage is the programming voltage Vpp. If you know the basics though the software is easy enough to follow.
Willem programmers appear popular fig 2. Getting to grips with EPROM programming, and having the gear to do it, is worthwhile if you want to maintain a vintage computer collection. Typically, my eraser will blank a chip in about 20 minutes. 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!
Otherwise there is great risk of zapping the ROM because voltage is applied to the wrong pin! Usually a status bar shows progress. What you need to do will differ depending the machine. The UV wavelength used is the same as that used for sterilizing equipment.
2532/2732 EPROM Adapter
Don’t look directly at the bulb when the door is open. However the programming devices mentioned below do handle these other chips. Beware though, as many modern ones will not handle the smaller capacity ICs like the and ones found in very old microcomputers. Once reprogrammed or “burned”they can hold their data for many years.
The Willem requires you to set jumpers and dip switches whereas my TOP allows chip selection from software. Not just the size but also the manufacturer. The software that comes with the programmer will manage the burning process. They are cheap and flexible but have a bewildering array of jumpers and switches to set.
EPROM: ICs & Processors | eBay
TOPS software showing a binary loaded into the buffer and ready to go! The ICs hold code, often an auxiliary program such as an application, utility or game which can be loaded immediately on startup. One is the READ voltage. Modern programmers use menu-based interfaces that are easy to use. There are a number of programmers on the market.
Typical values are 25v, 21v or These have a “C” between the prefix and size number e. Eprm example, one manufacturer might use 21vpp for their ICs whereas another may use 25vpp. Fig 1 shows my eraser.
For your average vintage microcomputer, EPROMS can be recognised by their clear transparent windows, normally covered by some kind of label.