[Arm-netbook] Warning about tablets/netbooks with detachable keyboards

Luke Kenneth Casson Leighton lkcl at lkcl.net
Wed Dec 14 19:20:18 GMT 2016

On 12/13/16, dumblob <dumblob at gmail.com> wrote:
> Hi Luke,
> just a tiny note about your mentions of a "tablet/netbook" in
> https://www.crowdsupply.com/eoma68/micro-desktop/updates/latest-from-shenzhen

 i do wish that crowdsupply could provide on-post comments, but then
they'd have to monitor them.

> In case you're planning to have the keyboard detachable (even worse if this
> detachable piece should have some connectors like USB), think of it twice
> as per experience of many users of different such tablets/netbooks (youtube
> is full of such reviews), the detachable connection is very fragile
> (because the detachable design requires a shallow or rather just "touching"
> connection in contrast to "sliding" deeper connectors like USB).

 ok.  first thing: have you heard of the alwaysinnovating touchbook?
it was the world's very first hybrid netbook / tablet.  most people
don't even know it exists, sadly.  as a monolithic design it would
ordinarily have a lifespan of about... six to eight months, but
because it was targetted at linux users that was actually
about...eighteen months / two years.  what killed it was the use of a
720mhz ARM Cortex A8, RAM limited to 512mb... no means of upgrading
except a whopping $50k for replacing the entire main PCB.

 anyway: the casework was extremely robust, with the
keyboard+extra-battery portion having inch-long "arms" at the sides to
securely and firmly hold the main tablet part in place... in a
standard USB socket.

 you have to bear in mind that i'm being quite realistic about this
whole exercise: if i can't design it to be robust in PLA with a
standard mendel 3D printer, and i can't get off-the-shelf generic
parts that are commonly available from multiple suppliers in huaqiang
rd, futian district, shenzhen, china, it ain't going in.

 so whilst what you're seeing is complaints based on a
fight-to-the-minimum (in terms of both thickness and price), i will be
designing stuff that's "chunky", realistically maintainable by a
lego-mindsetted individual, and built to last.

 therefore, i will *NOT* be attempting to replicate the existing slew
of magnetic catches and so on, apart from anything i won't be able to
get hold of them as they will have been custom-designed for specific

 i _do_ have a background in physics and mathematics which gives me
some mechanical design aptitude :)

> Therefore there will be a need for advanced SW means (from Linux kernel
> through all daemons up to GUI) to cope with interrupted keyboard input,
> interrupted USB communication, etc.). I'm though not aware of any such
> comprehensive solutions, so this will most likely become very painful and
> will stay so forever if introduced.

 USB.  simple as that.  problem goes away.  USB's already designed to
be interruptable.  people unplug keyboards and mice all the time.  the
linux kernel's had USB support since forever.  i don't expect there to
be any software problems at all.


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