Печатная плата Apple ][ 80-Column Text Card #142

1 отзыв на Печатная плата Apple ][ 80-Column Text Card #142

1. 

   Williams James – 14.01.2021

   I have enjoyed most of the PCBs from this shop but this one is really poor, it has taken me weeks to get it to work and it should be listed as untested as it could never work in its current configuration.

   The problems are:
   1. A0 to A6 of the external bus have incorrectly connected to the internal bus. you will need to cut the tracks to isolate them.
   2. If you are using a 74273 at U18 you will need a pull up resistor at X5
   3. U1 is a 7486 and not a 7485
   4. U3 should be a 2708, if you use a 2716 you will most likely destroy it because of the +12V and -5V supplies

   Tested on a Apple 2 Europlus — Now that I have fixed the above issues it works well
   Regards
   James