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

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Upload this code to your Arduino board and open the terminal program that you installed earlier. For the purposes of this tutorial, I'll assume you're using TeraTerm. On the computer we run a Python script that sends commands to the Arduino which responds by either reading or writing data. If you have the original files, there may be tools to describe programme flow (this will depend on the specific processor / controller). The key routines for this article are writeEEPROMSDP which writes a byte of data whilst SDP is enabled and disableSDP which disables SDP so you can write to the chip with the normal writeEEPROM function. disableSDP()

This adapter technique can be also used to read or program EPROMS that are not supported by your programmer as I did with these 2532 EPROMS for my Pet 3032. The programming "delay" is incorrect. There will be a setting for this somewhere in the software. It normally defaults to some value when the IC is selected. Try smaller or larger values and see if this fixes the problem. I found I had to change the delay value from default 5ms to 1ms before I had success burning my 2716 and 2732 EPROMS with my Top 853. Bear in mind an unsuccessful burn will probably require the EPROM to be blanked again.

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And we can finish off by moving the /WE connection from Arduino pin D13 to pin A2 and adding connections from A1 to /OE and from A0 to /CE. I don't know your programmer. But normally, you clear the buffer (fill the whole adress space of the 2716 EPROM with ffs), then read your file at the beginning of the buffer. So the ffs of the first half of the buffer will be overwritten by the content of the 2708 file. The second half will remain ffs. Then you can burn the buffer into a 2716. Key cloning is one of the most important part of our job. My policy is “better cloned as programmed”, because a cloned chip works for sure; while you can have lots of unexpected errors when you try to add a new key. DIP, SDIP, PLCC, JLCC, PGA, LGA, SOIC, SOJ, SOT, QFP, TQFP, PQFP, VQFP, MQFP, LQFP, TSOP, SOP, TSOPII, PSOP, SSOP, TSSOP, SON, EBGA, FBGA, FTBGA, VFBGA, μBGA, CSP, SCSP, QFN, HVQFN etc.

Here is an important piece of advice. KNOW THE CORRECT Vpp OF THE EPROM YOU WANT TO BURN. The incorrect voltage can kill it. Chances are your EPROM programmer will require you to select this value. Search Google and get a datasheet for your EXACT EPROM. Not just the size but also the manufacturer. Different manufacturers used different Vpps for their EPROMS. For example, one manufacturer might use 21vpp for their 2716 ICs whereas another may use 25vpp. Make sure you know the specs you're dealing with.

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Mike, your intro nails my situation. I’ve built Ben’s 8-bit computer and am working on an expanded version using AT28C256 chips. I only stumbled onto SDP a couple of days ago by using a TL866ii Plus programmer, experimenting with the EEPROM I so far could not write to, and then later was able to write to the chip using Ben’s programmer (already modified to fit the AT28C256). My brisk research turned up a number of references but yours stood out. However, I’ve now made the HW changes and have tried to get your code to work with it but nothing I’ve tried seems to result in disabling SDP, including adding capacitors to my board. Additionally, when I ran your code as is, I was able to discover that without manipulating /CE, a read after write was actually always returning the value that had last been written, and, in fact, nothing had been written to the EEPROM. This was verified by making sure /CE was low when reading and the actual contents of the EEPROM were returned. Have you been able to verify the contents of your one AT28C256 separately from your sketch code? On the other hand if you DID actually get it to work, I’m curious as to what I am overlooking and would welcome any additional insights you may have. NOTE: Although I do have a separate EEPROM programmer, I really want to get the BenEater version working for this. We can now turn to the software. I’ve made a fair few changes to the original software, largely to improve performance and remove redundancy.