Nama wrote:
I believe there are three LS157's connected to two 2114 ram. This RAM is then connected to the character ROM, which in-turn connects to the video generator circuit.
I take the DRAM statement back. I saw 3 rows of apparently DRAM chips and assumed this was all the memory. The 2114 is static memory, 1K by 4 bits. Two chips make a kilobyte that is apparently used as separate text video memory. Pin 4 is A3 but the address lines do not HAVE to be used in order. So check the traces from pins 1-7, and 15-17.
-Alex.