This is also the pin driving the on board LED and I’d rather use that for status information without risking corrupting the EEPROM. I’m also going to move /WE away from pin 13 of the Arduino. To get this to work we need be able to drive all three of the EEPROMs control lines. I’m assuming here that you already have Ben’s programmer for the 28C16 available to modifyīen’s design permanently connects /CE to ground and drives /OE via one of the 74HC595 shift registers.
#Eprom programmer 27c256 update#
Since I’ve already written code to write to a chip with software data protection via a Z80 I thought it would be helpful to update my own ‘BenPrommer’ to handle the 28C256 and to document both the hardware and software changes needed.
![eprom programmer 27c256 eprom programmer 27c256](https://3.14.by/files/1000/TL886-3.jpg)
My original ‘BenPrommmer’ with 28C16 EEPROM If you have a dedicated EEPROM programmer this is not a problem, the programmer will handle the data protection for you, but many hobbyists prefer to save a few pennies and using Ben’s own breadboard EEPROM programmer. The SDP can be disabled but this requires a similar command sequence 1. You can do the same with the 28C256 if the SDP is disabled, but if it’s enabled then you need to send a specific ‘command sequence’ to the chip. With the smaller 28C16 (as used by Ben) you can write data in the same way you would with a RAM chip, just by strobing the write pin.
![eprom programmer 27c256 eprom programmer 27c256](https://i0.wp.com/dragaosemchama.com/wp-content/uploads/2016/10/schematic.jpg)
![eprom programmer 27c256 eprom programmer 27c256](https://320volt.com/en/wp-content/uploads/2011/01/universal-programlayici-devresi-willem-programmer.jpg)
And some of those are using larger EEPROM chips such as the 28C256.īut there’s a catch with the 28C256: it has something called software data protection (SDP), which protects data from being accidentally overwritten. And many of those are either moving on to more advanced projects or using slightly different hardware for the build. Many people are learning, like I did, about computer hardware by following Ben Eater’s 8-bit breadboard computer build.