I was able to find some in-depth information on the LK201 keyboard, as well as the DEC mouse used with Windows 1.0 on DEC Rainbow 100 (also on later DEC VAXMates).
Linux people already have a working LK201 and LK401 keyboard, as well as a mouse driver (below, though i can't tell if it's of use) :-)
The DEC hockeypuck mouse (VSXXX-AA and -GA) had a proprietary, 7 pin 'PS/2 style' adapter and had to be plugged into the serial printer port of the DEC Rainbow 100 (via another adapter).
It was in fact a "200 counts per inch" serial mouse (4800 bps, 1 start bit, 8 data bits (LSB first), 1 parity (ODD), 1 stop bit, half-duplex) with a SIGNETICS SCN2661.
There are probably some similarities to Logitech mice (rumours say the Logitech C7 serial mouse for PC could be switched into a DEC compatible mode, at least for AutoCAD, and the DEC VAXMate mouse could be switched into a PC compatible mode via MOUSE.COM and/or MOUSE.SYS).--------------------------------------------------------------
APPENDIX B : LK 201 Keyboard specification
(pages 357 +)
APPENDIX C : Mouse sub system; chapters C3 => C-12
(pages 403 and on)
HTML index was easy to find, only the original, 120 MB PDF was not (working mirror below):
VCB02 Video Subsystem Technical ManualCompany: Digital Equipment Corporation
Part: EK-104AA-TM-001
Date: 1987-02
Keywords: LK201HTML INDEX:
http://manx.classiccmp.org/details/1,21 SLOW DOWNLOAD (119 MB!):
http://z80cpu.eu/mirrors/oldcomputers.dyndns.org/rechner/dec/manuals/decimages/104aatm1.pdf--------------------------------------------------------------
"News about proprietary mice made by Digital Equipment Corporation"
http://web.archive.org/web/20080509094502/http://www.cs.utk.edu/~shuford/terminal/dec_mouse_news.txt --------------------------------------------------------------
DEC LK201 and LK401 keyboard driver for Linux, based on sunkbd.c (C) by Vojtech Pavlik
(DEC Rainbow 100, also for DECstations + VAXstations)
http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/drivers/input/keyboard/lkkbd.c --------------------------------------------------------------
Bits of information from PAGES 53 - 70 of
http://www.bitsavers.org/pdf/dec/ethernet/EK-DEPCA-PR-001_Apr89.pdfThe mouse has two operating modes, prompt mode and incremental
stream mode. In prompt mode, which is the powerup default, the mouse generates a report in response to a request mouse position command.
In incremental stream mode, whenever the mouse moves it generates a report of that movement. It also reports a change in button position since the last report. No report is generated when the mouse is motionless and no buttons have been changed
The mouse can transmit two reports, a 3-byte position report and a 4-byte self-test report.
Table 3-1 Mouse Command Summary
ASCnValue Hex Value Function D 44H Prompt Mode
R 52H Incremental Stream Mode
P 50H Request Mouse Position
T 54H Invoke Self-test
Zx 5AH :xx Vendor Reserved function
- - - - - - - - - - - - - - - - -
EDIT: "GPL Driver for DEC VSXXX-AA and -GA mice by Jan-Benedict Glaw <jbglaw@lug-owl.de>"
http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/drivers/input/mouse/vsxxxaa.c 
