Price is $75 for each PCB and includes shipping. No components or hardware is included.

See my web page for details:

http://www.willegal.net/appleii/apple1-datanetics.htm

Despite very limited demand for these keyboard reproductions, I decided to pull the trigger on another batch. I think I am having more than enough made for everyone that has expressed interest, but in any case, let me know, if you are seriously interested in getting one or more.

This time, I will be only selling blank PCBs, no brackets or anything else, so these are for the advanced hobbyist, only. I may do a brief instruction sheet, if I have time, but most of the info needed to build one up, is already on this blog (check the Datanetics category) or my website. I have to think some more about price, but I expect they will be around $80, including shipping. Even to me, this seems high for a blank PCB. However, keep in mind that these are fairly big boards by modern standards, and I only make a few in a batch.

Like all my PCBs, they are made to a very high quality standard, right here in the USA.

While working on a micro-controller replacement for the MM5740/AAE keyboard decoder used on the Datanetics keyboard, I discovered a way to send the unique Apple 1 backspace keycode (0x5F). You need to connect line X4 of the matrix to one lead of a blank keyswitch and Y3 to the other lead of the same keyswitch. Then by holding down shift and pressing that blank key, you can generate the 0x5F needed to backspace the Apple 1 monitor.

Note that you could also rewire the left arrow key of a MM5740 based Apple II keyboard to accomplish the same thing. Unfortunately there is no easy way to avoid the requirement of pressing the shift key to generate the correct code.

In the PDF at the end of this post, I have captured some notes associated with an abandoned project to use an ATMEL AVR – ATMEGA16 in place of a National MM5740 keyboard decoder. Both parts come in 40 pin DIP packages, which makes the AVR substitution idea work pretty well.

The initial idea was to check to see if the AVR could be used as a plug in replacement, with some socket stacking and rewiring. I was also considering building a Datantetics Apple 1 and Apple 2 compatible keyboard using Cherry key switches and an AVR as the encoder. The reason why I stopped this project is that costs would probably have forced a selling price of close to $200. These notes are associated only with mapping the pinouts. I had assumed that if I could make a reasonable mapping that the software would be pretty straight forward.

It turns out that there are just enough pins to do the job without any loss in functionality. The strobe control, Output enable (OE) and shift lock functions are not used on Apple II/IIplus or earlier Datantetics keyboards. The Bounce Mask function can be accomplished in the AVR’s software. The clock of the AVR can be generated by either the internal RC oscillator or an external crystal input.

The PDF follows:
MM5740-to-AVR-mapping

I’ve done several online searches for a complete MM5740 data sheet over the last several years. There is a version that can be found on many of the data sheet archive search engines, but it is missing at least one page, containing crucial information. I knew it was part of National’s MOS/LSI data book from the mid ’70s, but I couldn’t locate an online version of that book, and I really didn’t want to buy a physical copy. One of the key questions that couldn’t be answered with the existing online data sheet, is what exactly is the difference between the AAC/AAD/AAE/AAF versions.

Finally while exploring the possibility of using an AVR as a replacement decoder for the MM5740, I did another search and the data book turned up as a PDF at bitsavers.org. The last page of the data sheet show that the AAE version has N-key rollover and the AAF version has 2-key rollover. Otherwise they are the same. This means that the AAF version should be usable in the Apple/Datanetics keyboards, only with the loss of the n-key rollover feature. Also, in this data book are some app notes, that provide information on the AAC and AAD versions. Those versions decode the matrix differently, in order to make using an external PROM decoder simpler. They will not be compatible with Apple/Datanetics keyboards.

Once I figure out the best way to cut it out of the complete data book, I’ll put a copy of the complete MM5740 data sheet and associated app notes up on one of my web pages. For now, you can try to download the complete National MOS/LSI data book from bitsavers.org. Recently, I’ve have trouble accessing that site, but if you are persistant, you should be able to get through.

While I’m waiting for Brain Board beta feedback, I finished assembling the Datanetics Keyboard Enclosure I built to match my Mimeo 1 Enclosure. Here is the final result. Not my finest work, but it will have to do.