Datanetics Rev B Keyboard
is one of the most common keyboards that can be found with an
Apple 1. Here is a link to an original set of directions
how to connect this keyboard to an Apple 1.
get a chance I'll clarify and provide more understandable
instructions (check out my blog).
I have built a reproduction. As part of
the reproduction process, I reverse engineered the board and created
their own patented keyswitches. I've run across two types of
these keyswitches, those with straight stems and those with slanted
stems, as shown below. The Datanetics rev B used switches
far as I can tell, sources for original new keyswitches and caps are
non-existant. However, very early Apple II and Apple II plus
computers used keyboards made by Datanetics. Most of the keycap set
used by Apple is close enough to the Datanetics keyboards to be
Early Apple II plus computers may be considered the only
source for these Datanetics keyswitches and key caps.
other difficulty is the keyboard encoder. This part is a
National Semiconductor MM5740/AAE. This part is difficult,
sometimes impossible to find. When you do find them, they
frequently come with a mysterious defect that causes randomly
key strokes. They are also sensitive to static electricity,
handle them with care, if you do find one. If you can't find
working one, a micro-controller could be programmed to perform the
function. It would have to be mounted on a daughter card,
the power connections on the MM5740 are in non-standard locations.
The data book and app. notes for this part can be downloaded
is a not to scale rough drawing of the stiffeners used by the
Datanetics Rev b
is my reproduction Datanetics rev B connected to the Mimeo.
Build Your Own Datanetics Reproduction Keyboard
See my Datanetics
for more information my reproduction.
A parts list can be derived from the schematic.
A couple of things to be aware of before taking on this project.
- 7 resistors
- 2 100 ohm
- 1 360 ohm
- 1 3K
- 1 3.6K
- 1 30K
- 1 510K
- 3 capacitors
- 250 pico farad
- .01 micro farad
- .68 micro farad
- 5 dip sockets
- 1 40 pin
- 2 16 pin
- 2 8 pin
- 5 ICs
- 1 MM5740/AAE (hard to find, but occassionally available from
- 2 555 timers
- 2 7404 inverters
- 56 datanetics keyswitches with key caps (most practical
source is to pull from an "early" apple II plus) - be aware
a few extra keys beyond what you can pull from a single Apple II
- 1 datanetics spacebar assembly - spacebar, supports on each
end and support wire (most practical source is to pull from an
"early" apple II plus)
- brackets - dimensional drawings above
Corey Cohen wrote this build manual based on his experience
building a reproduction Datanetics.
- The matrix vias are plated through and must be drilled out to
eliminate connectivity between top and bottom copper layers
- this must be done carefully or you risk delaminating the
- the holes are drilled undersize, to .026 mils dimension, you
should drill them out to about .036 mils (an 1/32" drill
- use a sharp drill bit, in order to reduce risk of
- I recommend drilling partway through from each side, to
reduce the possibility of delamininating pad
- check connectivity after drilling out with an ohm-meter to
ensure that the connectivity is removed.
- This reproduction faithfully reproduces a mistake that existed
the original Datanetics rev B. Fixing this requires
trace in two places and jumpering. My blog has details of
- The fit of the plastic studs on the keyswitches to the PCB
may be tight. If you can't get a keyswitch to mount flat
keyboard, you can ream the mounting holes slightly. There
electrical connection in these holes, so removing plating is not
- There is no stiffener across the top of the board because
it is insulated, it would short out the traces running across
Datanetics PCBs are all sold - As they were very slow sellers, I'm not
sure when or if I will make another run. If you can
find around 10 friends that would all commit to buying them,
I would do another batch.