Hi al all, I have an old computer without any documentation and without its keyboard. Checking the 16-pin flat cable connected to the keyboard connector cannon 25pin I find that: Cannon Pin Segnale 5 to Bit0 Z80BPIO 6 to Bit1 Z80BPIO 7 to Bit2 Z80BPIO 8 to Bit3 Z80BPIO 21 to Bit4 Z80BPIO 20 to Bit5 Z80BPIO 19 to Bit6 Z80BPIO 18 to Bit7 Z80BPIO 17 to BSTB di Z80BPIO the default signal is a square wave 3Vpp 15 to +5Vdc 2 to GND 16 to Gnd 14 unknown where it would go and on defaut there is no signal 4 it is connected to pin 13,14,27 of one Z80DART and on default there is a square wave of 5V pp period 6,5microS 3 it is connected to pin 28 of the same Z80DART RxDB and on default there is a square wave1Vpp 1 it is connected to pin10 of a 74LS123 and at default there is a + 5V In an old review on this old computer was explained that it was necessary that to have the firmware prompt we need to press together two distinct keys called BREAK present on his keyboard. I tried to connect a parallel keyboard respecting the strobe, all the data bits and power supplies,and gound but I can not have the prompt. Here some pics of this machine: https://www.dropbox.com/sh/14hqo3o8e...m44JPYbta?dl=0 Ask to someone who could explain to me the meaning of those above links to a Z80 DART presents on a parallel port.. Regards