USB Programmer for EPROM 27C, (27C256, 27C512, etc.)

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a b c "1971: Reusable semiconductor ROM introduced". Computer History Museum . Retrieved 19 June 2019. For some reason I only had one rom that read correctly on the programmer. all the others showed up as blank, even though I knew they weren't. Then I noticed that one of the wires from the parallel port had come loose. Fixing that got everything working properly again. (it was either CA1 or PA6) We put 0xFF in there, because this is the value of an erased EPROM cell. So it could be programmed later without erasing the entire chip. The Program is extremely user friendly. However, make sure that the programmer is plugged in correctly before you start. Accompanying the main menu, there will be a 'test state' printed. The 'test state' will inform you of an EPROM'S presence in the programmer, if it is blank or not, and the size and name of any non-blank EPROM present. This test state is continuously updated as long as the menu is displayed."

The smallest currently available (from the main electronic suppliers) EPROM is a one time programmable [OTP] (you can ‘burn’ them, but there is no window to erase them) 256K bit (32K bytes) EPROM such as a 27C256. But only half (16K bytes) can be normally be seen by the microprocessor. You can wire up in an extra wire, then the machine will see one physical chip as two 16K byte ‘ROM chips’.Oklobdzija, Vojin G. (2008). Digital Design and Fabrication. CRC Press. pp.5–17. ISBN 978-0-8493-8602-2. Microsoft 64-bit operation systems doesn't allow direct access to LPT port, therefore the communication speed between PC and programmer is very low. In case of Windows x64 OS we recommend to use only USB connected programmers. And that’s it. I found I didn’t need any delays within the code and, despite what the datasheet shows, I didn’t need to toggle /CE between every write, but I’ve left them commented out within the code in case you have problems.

EEPROMs can be a bit temperamental, especially with fake chips around. Different brands can behave slightly differently, so what works for me with my setup may not work for others. Note: This example assumes you are using the latest version of the Arduino IDE on your desktop. If this is your first time using Arduino, please review our tutorial on installing the Arduino IDE. or 27C512 are double the capacity of a 27256 / 27C256. These require two extra wires. Then the machine will see them as four 16K byte ‘ROM chips’.I do still have some old eproms that have been stored in my mums loft for ages. These are the ones with the square window in. Signals are transmitted through the connection pins of the chip programmer into the target device. Some devices require data on the serial pins while others receive the data via a serial interface. I had a Willem but it died so my current programmer is a Top 853 out of China (fig 3). It's also inexpensive, is completely software driven and can supply all necessary programming voltages from a USB link. 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! It's almost completely unreadable. If you know the basics though the software is easy enough to follow.