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 a
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 useful.
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 repeating
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 same
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 blog entries
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 littlediode.com)
- 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 you'll need
a few extra keys beyond what you can pull from a single Apple II plus
- 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
Bare PCBs with no components or hardware are now available for $75, shipped. Send me an email for ordering information.
- 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 copper pads
- the holes are drilled undersize, to .026 mils dimension, you
should drill them out to about .036 mils (an 1/32" drill bit will
- use a sharp drill bit, in order to reduce risk of delaminating pad
- 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 on
the original Datanetics rev B. Fixing this requires cutting a
trace in two places and jumpering. My blog has details of this
- The fit of the plastic studs on the keyswitches to the PCB holes
may be tight. If you can't get a keyswitch to mount flat to the
keyboard, you can ream the mounting holes slightly. There is no
electrical connection in these holes, so removing plating is not
- There is no stiffener across the top of the board because unless
it is insulated, it would short out the traces running across this area.