here is a Active ps/2 usb converter that works with 99% of the old keyboads
model m and equiv
  On 7 Nov 2011 at 20:50, Tony Duell wrote:
  Howeever, since the PC/AT keybaord itnerface is
well-docuemtned,
 wouldn't it be better to design a proper (i.e. without bugs) PC/AT
 keyboard to USB converter? 
 The guy offers the artwork for a replacement PCB that mounts in the
 Model M; he's done the programming--the job is essentially a solder-
 ti-togethere-and-program-the-AVR no-brainer.
 I can buy AT-to-PS/2 converters; some might even work correctly.  Why
 would I want to build one?
 --Chuck