[sf-lug] Hardware hack for laptop - Raspberry Pi in the optical slot.

[Rick Moen]

Quoting Bobbie Sellers (bliss-sf4ever at dslextreme.com):

> Hi LUGers,
> 
> I asked sometime back one of our knowledgeable members about
> this sort of thing and was told it was impossible.
> 
> <https://www.tomshardware.com/news/raspberry-pi-zero-replaces-broken-laptop-optical-drive>

I very much doubt that anyone claimed _this_ sort of thing is
impossible.  It appears the problem is that you probably didn't
properly understand what Oliver Child, the experimenter, did.

> The laptop now runs on the Raspberry Pi.

No, it very much does not.

Oliver's RPI Zero W merely lives inside the hollow space normally
occupied by the Lenovo ThinkPad T420's modular, slide-in optical drive
(which got broken).  The _only_ connection between the RPI Zero W and
the computer that houses it is power-feed pins from a SATA cable, thus
supplying +5VDC and ground cables that he soldered to the connection
pads for power connection on the back of the Pi.

There is no other wired connection of any kind between the two
computers.  In particular, the only way to have a network connection
between them is courtesy of the RPi having a wireless network chip.
Towards that end, Oliver connected a small LED display to the RPi so the
RPi can display its DHCP-assigned IP address, there, for the user to see
by peering over at it, shining out through the bezel on the side of the
optical drive bay.

Armed with that IP address, the user can then connect to the RPi over
wireless TCP/IP, e.g., for a VNC connection.  The user can of course do
this from the Lenovo, _or_ from any other machine able to reach the
RPi's wireless network.  (In theory, Oliver could have extended an
ethernet connection out of the size bezel, instead, but didn't.)

So, it's a nice little way to give a tiny RPi computer a home and power
it off a laptop's power supply -- but it's nothing like the laptop
"running on the Raspberry Pi".

> But it takes a 3D printer to produce the board that makes mounting the
> RP in the optical drive slot possible.

Well, I don't know about _that_.  Oliver found that the most expedient
way to make a plastic carrier with the same size and shape as the
optical drive tray -- by 3D-printer extruding one.  However, obviously
any other approach that gives the user a widget the right size and shape
to slide into the optical drive tray would serve fine -- including maybe
detaching the optical drive from its tray and using the latter.