name:         HT6513B
function:     M+ Plug & Play Mouse Controller
package:      DIP16,16
manufacturer: Holtek

      +--()--+
HB_LB | 1  16| VDD
 TEST | 2  15| Y2
   MS | 3  14| Y1
 OSCI | 4  13| X2
 OSCO | 5  12| X1
  RTS | 6  11| L
 RXDB | 7  10| M
  VSS | 8   9| R
      +------+


This pinout came from the Chipdir:
http://www.chipdir.org/