MM5740AAE Replacement Keyboard Encoder [MM5740AAE/N]

MM5740AAE Replacement Keyboard Encoder [MM5740AAE/N]


Universal Replacement for the National Semiconductor MM5740AAE/N, also known by other names.

Encoder should support ANY machine requiring the MM5740AAE/N – specifically the Apple ][ and Apple ][ Plus using “Datanetics” style keyboards.

Has been fully tested in: Apple ][ Plus with Datanetics Keyboard model 01-0425-05, and on an replica Apple I with the Willegal Apple I keyboard clone.

Encoder can support many other custom key mappings. If you would like a custom design, contact us for details.


  • Is your encoder actually faulty? Please note that not all keyboard issues are caused by a faulty encoder. Any number of other support chips in your vintage machine may cause similar symptoms.
SKU: MM5740AAE-R_v1 Categories: , , , ,


The keyboard encoder in my Apple /// failed and I didn’t want to scavenge another Apple /// to get one. So designed a replacement. And then I thought, why stop there?

I kept going and used my previous work as a base to replace the National Semiconductor MM5740AAE (a.k.a. MM5740AAE/N) keyboard encoder. Got a busted Apple ][ Keyboard? Need an off-the-shelf solution for your hobbyist electronics project? This will fit the bill!

Designed by Joe Strosnider, all key functions have been meticulously mapped, traced and tested. Extra testing and functionality confirmation by Logan Greer and Phillip Allison. Special thanks to Cole Rise for sending me his entire Apple I reproduction system for testing with an “authentic” setup.

Each unit lovingly assembled by hand in Ohio. ♥

Additional information

Weight 0.3 oz
Dimensions 2.1 × 0.75 × 0.75 in
Include 40 Pin Socket?

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