Editing MX13 SpaceSaver Keyboard (section)

===TrackPoint IV===
[[Image:MX13-TrackPoint.jpeg|thumb|right|300px|TrackPoint IV device on the MX13 keyboard (shown with raspberry-color cap).]]

A defining feature of the MX13 SpaceSaver keyboard is the integration of a [[Trackpoint|TrackPoint IV]] pointing device.
The TrackPoint IV is the newest iteration of IBM's TrackPoint line and includes convenience features such as a middle mouse button, negative inertia, and press-to-select.
The middle mouse button can be used in conjunction with the pointing stick to simulate a scroll wheel.
Negative inertia (marketed under the name ''QuickStop response'') contributes to more precise positioning of the mouse pointer.
Press-to-select allows a downward pressure on the pointing stick to emulate clicking and dragging the primary mouse button.

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====IBM SpaceSaver II Keyboard====
[[Image:IBM-SpaceSaver-II.jpeg|thumb|right|300px|IBM Space Saver II keyboard.]]

The IBM SpaceSaver II (SSII) keyboard is a great source from which to harvest IBM TrackPoint components for use in custom keyboards and keyboard modifications.
The SSII uses a rubber-dome mechanism to implement its key switches and on that basis is not terribly interesting as an input device.
What makes the SSII stand out, however, is the inclusion of a TrackPoint IV with sufficient height to be usable on so-called "mechanical" keyboards.

The only other TrackPoint IV product known to have sufficient height is the [http://support.lenovo.com/en_US/product-and-parts/detail.page?&LegacyDocID=MIGR-4WKSWX IBM TrackPoint USB Space Saver Keyboard].
Other extant TrackPoint keyboards with sufficient height (e.g., the IBM Model M13, IBM TrackPoint II keyboard) are TrackPoint II devices, which lack the negative inertia feature of the TrackPoint III and the middle mouse button (used for scrolling) of the TrackPoint IV.
All other known TrackPoint implementations are for low-profile keyboards, such as those used on ThinkPad laptops.

It also helps that the TrackPoint stick on the SSII keyboard is black, which looks nice, and the button assembly does not take up a lot of space.
When selecting parts for the prototype build, other TrackPoint IV keyboards were surveyed (including those from ThinkPads), and the SSII button assembly had the smallest footprint as could be determined from pictures.

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[[Image:SSII-screws.jpeg|thumb|right|200px|SSII case screws hidden beneath middle mouse button.]]
When disassembling the SSII keyboard, it is necessary to carefully remove the middle mouse button to access and remove two screws, as seen in the picture on the right.
More information about the process is available [http://www.58bits.com/blog/2008/10/18/the-internet-is-amazing here].

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[[Image:SSII-TrackPoint.jpeg|thumb|right|200px|TrackPoint pointing stick and button assembly removed from an IBM SpaceSaver II keyboard. The pictured button assembly was cut from the SSII enclosure using a Dremel (i.e., it is not separable without damaging the keyboard).]]

The TrackPoint stick is easily removable from the SSII and can be adapted to staggered Cherry MX layouts with some modifications to the key switches.
The TrackPoint controller is implemented on the same circuit board as the SSII keyboard controller, however.
So it is harder, if even possible, to physically separate, though the two circuits are powered separately and can be run independently.
The approach taken on the MX13 therefore is to embed the entire SSII logic board, but only activate the TrackPoint portion.

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====SSII Controller Board====
[[Image:Ssii-controller.jpeg|thumb|right|200px|IBM SpaceSaver II controller with labeled TrackPoint solder points.]]

The solder connections for wiring up the SSII controller are pictured on the right.
In order to fit the SSII controller in the MX13 case while keeping a low profile, it is necessary to de-solder the tall, female ribbon connectors from the board.
There are two ribbon connectors for the keyboard matrix, one for the external PS/2 mouse input, and one for the TrackPoint stick.
The latter is required to connect to the TrackPoint, although it is necessary to add extension wires between it and the SSII controller (points labeled "To TrackPoint" in the picture) since the TP ribbon does not terminate at the location where the SSII controller board will be positioned inside the MX13.
So make sure not to damage this connector when removing it!
The other connectors can be discarded.
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====Modified key switches====
[[Image:MX13-TP-switches.jpeg|thumb|right|200px|Key switches that have to be modified to accommodate the TrackPoint stick in the MX13 keyboard.]]

The G, H, B, N, and V key switches all have to be trimmed to accommodate the TrackPoint stick, as shown in the picture to the right.
To do so without removing portions of the switch that are critical to its operation, the switches are rotated 90 degrees.
It is very likely that these switches will not support spring swapping without complete removal of the switch from the keyboard matrix and mounting plate.

In the case of the B switch, it needs to be trimmed to the extent that its ability to grip the mounting plate is compromised, and must leverage the TrackPoint stick for support.
Super glue was also applied to the switch housing to bond the top and bottom parts together, as the clips on one side were removed.
In future designs, PCB-mounting could be useful for better supporting these keys.
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====TrackPoint LEDs====
====Mouse buttons====