What is it?  
This is a complete kit for an Atmel 28C256 adapter. (Does NOT include Atmel 28C256)  
Kit comprises of:  
1 x PCB  
1 x 47k Resistor  
2 x 14 way header  
1 x 4 way DIP switch  
1 x 28 pin DIL socket  
Why did you make it?  
When I am developing programs for inclusion in the 27C256 EPROM of my 65C02 SBC, I find it really tedious having to keep UV erasing them for any program changes.  
This adapter allows me to program a 28C256 EEPROM and then fool my 65C02 SBC into seeing it as a 27C256. Any changes needed are programmed into the chip after changing the switch settings back to program mode.  
What makes it special?  

It is a very simple and useable design.

Switch Settings  
1 & 4 on, 2 & 3 off : Program 28C256 (Read and Write)  
1 & 4 off, 2 & 3 on : Read 27C256  
I sell on Tindie  
(c) 2021,2022,2023 Paul Bartlett