name:         HT6P20D
function:     2**24 OTP Encoder
package:      DIP/NSOP16,16
manufacturer: Holtek

    +--()--+
 D1 | 1  16| D0
 D2 | 2  15| PGMB
 D3 | 3  14| SIO
VSS | 4  13| VPP
 NC | 5  12| VDD
 NC | 6  11| DOUT
 NC | 7  10| OSC1
 NC | 8   9| OSC2
    +------+


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