Usenet link explains how to use AT keyboard with AT clone Wyse PC. and the arthur DID.
it means either
1) Wyse PC has added feature in it's BIOS that it can accept Wyse proprietary keyboard, XT keyboard and AT keyboard.. or
2) Wyse PCE keyboard is essentially same with AT keyboard except RJ9 modular connector.
I examined the PCB and determined pin assignment as attached jpg.
made an RJ9 to PS/2 cable and then hooked the board to my main system.
Result; LEDs all came on upon powering up PC, no blinking but just stayed there lighting.
unable to type p/w to log in windows like I couldn't before.
Conclusion; 840358 might be incompatible with usual windows PCs if my pin assignment is correct. Wyse PC is something special like late PC XT which accepts both XT and AT keyboard.
Hope somebody can make it work with usual PC.