|Full Name||IBM 101-Key Keyboard with 25mm Trackball - PS Style|
|Part NumberPart Number
The number used to describe this keyboard's specific release; usually specific for a target region, language or SKU, etc.
A designation from my own type naming scheme used to categorise this keyboard with or from others by their common features and market intent but may/may not be derived from official names.
|Model M5-2 Trackball Keyboard|
The name of the known switching mechanism that lies under this keyboard's keys.
|IBM membrane buckling springs|
|Original KeycapsOriginal Keycaps
The keyboard's original keycaps' material and text/symbol printing technique.
|PBT with dye-sublimated legends|
The style of this keyboard's flip-out or extendable feet. If applicable, this may also state how many levels of height adjustment are available and whether the feet could be rubberised.
|Single-setting flip-out feet|
The protocol(s) this keyboard can use to speak to the host computer (eg, scancode sets).
|IBM scancode set 2|
The keyboard-to-host connection. This is could be a description of a cable (its colour, whether its coiled, whether its detachable, and what connector is at its end) or the name of a wireless technology.
|Grey coiled-style detachable 6-pin SDL to dual mini-DIN PS/2 cable|
|Form FactorForm Factor
The standardised or universally acknowledged name for this keyboard's layout form factor.
|Built-In MouseBuilt-In Mouse
Possible pointing devices this keyboard could carry. This could be a brand name, name of the sensor technology behind it, or a generic description in lieu of the former details.
About this keyboard type
The Model M5-2 is one of two variants of the Enhanced Keyboard featuring an integrated trackball pointing device attachment, along with the M5-1. The M5-2 uses a 25mm trackball placed on the top-left corner of the keyboard case and features eight mouse buttons; two for left and right click and two for left and right stepped-click, with both pairs repeated on the back-side of the trackball module. Unlike the M5-1, the M5-2 has remained in production and continues to be produced by Unicomp as the Unicomp Classic Trackball Keyboard (also previously called "On-The-Ball"). Collectively, the M5s were the last introduced Model M variants to feature a modular SDL connection. However, Unicomp has since moved the M5-2 to a fixed cable design.