On Sun, Nov 11, 2018 at 6:32 PM Rob Jarratt via cctalk <cctalk@classiccmp.org> wrote: > > I am still working on the causes of a Reset on my Pro 350. One 8-pin DIP > chip that I have traced to is marked as follows: > > > > 9643TC-B1 > > F 8313 > > KOREA > > > > It is very close to the F-11 chips at the bottom left and marked E135 in > this picture > https://rjarratt.files.wordpress.com/2018/10/system-board-labelled.jpg
How about a Fairchild 9643TC dual TTL-MOS level shifter? I found a datasheet with Google. The pinout seems to be : 1 : Input A 2 : Enable Input 3 : Input B 4 : Ground 5 : Output B 6 : Vcc2 (Output stage Vcc) 7 : Output A 8 : Vcc1 (Input stage Vcc, normally +5V) -tony