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+# Default keymap for m122-3270
+
+This keymap is intended to make the PC/3270 122-key IBM keyboard work as closely as possible to the standard
+PC/3270 keyboard's (part number 1397000) original mapping. Two layers are defined: layer 0 is the PC layout,
+using the blue legends on the PC/3270 keys (as shipped by Unicomp; I don't have the original keycaps, and I
+know there are a few differences), while layer 1 is the 3270 layout, with keycodes selected to make the `x3270`
+suite do the right thing with each key as pressed. The idea here is, eventually, to get `x3270` to
+automatically shift the keyboard to layer 1 when it gains focus.
+
+When layer 0 is active, the upper left key of the 10-key pad is Escape, the Reset and Enter keys are Control, and
+the comma and dot keys act like normal PC keys (< and >, repectively, when shifted). The Ctrl key (bottom right
+of the left-side 10-key cluster) is always the left GUI key. PA2 and Jump/PA3 are PgUp and PgDn, respectively,
+and the backtab key is End. The Rule/Home key is Home. The key next to the Escape key is Scroll Lock when unshifted,
+and Num Lock when shifted.
+
+When layer 1 is active, the keys do their labeled functions. The only keys that don't do anything are CrSel,
+ExSel, and Jump, though only a few of the alternate functions (on the front of the keys) work: left/right/delete
+word and PA3. The rest aren't emulated by x3270. Many of the keys that have function in PC mode will *not* have
+that same function in 3270 mode, since x3270 uses different keystrokes to accomplish the same function.
+
+To manually switch to layer 1, hold the Zoom key (the one on the far lower left of the keyboard) and press Clear
+(the one at the top right of that same block of 10 keys); to switch back to layer 0, hold the Zoom key and hit
+Attn (the one at the top left of that block of 10). Holding the Zoom key and the spacebar gets you to keys that
+control QMK itself: Zoom-space-R resets to the bootloader, Zoom-space-E erases the EEPROM (which currently does
+nothing), and Zoom-space-D turns the debugger on and off.
+
+Note that you need to set your Linux system to use the Scroll Lock key as the Compose key in order to get the
+cent sign to register as intended, and add the following lines to a file in your home directory named `.x3270pro`
+to make Dup and Field Mark work:
+```
+x3270.keymap.m122: #override \
+ Ctrl<Key>F: FieldMark()\n\
+ Ctrl<Key>D: Dup()
+```
+You need to then invoke `x3270` with the parameter `-keymap m122` to activate those definitions.