The Digicool Things TL866 EPROM Programmer Adapter for 27C400/800/160 and 27C322 16bit EPROMs, gets a celebratory update to v2 for 2025.
Some years ago. In fact, way back in 2017, I designed an EPROM Adapter for reading and programming popular Retro 16-bit ROMs, using the low cost and hugely popular TL866 series Programmer (which many retro hobbyists have to hand).
As far as I know, this EPROM Adapter was the first one to implement my innovative “Rotary Switch” Bank select.
Join me, as I celebrate my improved Adapter, by coming up with an even further improved v2 design.
Background
At the time (circa 2017), I was frustrated with the various fiddly DIP switch or jumper based Adapters, which were randomly available (and not always even available), from different sellers on eBay.
Therefore, I designed the current Digicool Things EPROM Adapter, and over the past few years many have been shipped, to all corners of the world.
In addition, I’ve seen at least one copy of my original Rotary switch based design.
Given how my adapter has helped many other retro enthusiasts with their own projects over the last few years, I decided it would be fun to revisit the design.
I thought I’d take the time to see if I can celebrate my improved Adapter, by coming up with an even further improved v2 design.
Given the proven success of the existing v1.2 model, this would seem an interesting challenge.
Designing Version 2
So, I worked away in the background, and produced a “new improved design”, that I was finally happy made a worthy successor!
Not to stop there, I then also made real use of the new design, regularly and exclusively, for the past few months, to further ensure that I was 100% happy that it was a worthy upgrade!
So, without further ado, I now present the EPROM Adapter v2.
Version 2 Enhancements
The first thing you’ll notice about the new v2.0 Adapter is that I’ve chosen to go with a black PCB, instead of the standard green PCB of the prior version.
I decided the black PCB looked a lot nicer, and gave a more finished look for this open PCB based product.
Now, apart from the PCB colour, the v2 Adapter includes the following enhancements:
- A more appropriate 8 position Rotary switch was chosen, to match the maximum 8 banks supported. This replaces the BCD / 10 position switch of the prior version.
- The Rotary switch has been upgraded to a 3:3 pin footprint package, to ensure optimal mechanical robustness. This replaces the 1:4 pin footprint of the prior version, where one side only had one pin mechanically securing the switch to the PCB.
- For the new design, the surface-mount device count has been reduced from 7 components to just 5, improving the manual surface mount assembly efficiency.
- The Bank Selected EPROM Address pins are now nicely “logic gate” level driven, instead of just using direct-switched pull-up resistors. Making for a much more elegant solution.
No Price Increase!
Now, to cap it off, despite this list of design improvements, the v2 Adapter remains at the same price as its predecessor.
I decided that even with some additional component cost, I would absorb this, so that there was no additional cost for end users.
Updated “Black & Gold” Edition
In addition to all this, the v2 enhancements have also been applied to the special “Black & Gold” edition that was release for 2024.
Combined with the new black coloured PCB, this makes the “Black & Gold” edition now really look the part!
Conclusion
So, there you have it. I think my perfectionist tendencies towards this Adapter have now been fully satisfied.
If you’d like one then please visit my Tindie Store.
If you already have enjoyed the use of v1, then you might even consider celebrating with me, by also upgrading to v2.
Have fun!
Discussion
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