Posted By
SukkoPera
on 2023-03-17
19:41:59
|  Re: New Project: Hannes-compatible 256k RAM Expansion
Right, I haven't updated this thread in a while, I guess it's about time!
I made a V2 of the board, which included a full 8-bit register and a 74x245 allowing to read it back. Somehow I managed to squeeze it all in a single PCB (whose chip count grew to 15!), which was *almost* perfect: the 6529 replacement circuit was the one suggested by @TLC but I decided to use a NE555 instead of the 74x74 and that required the trigger signal to be inverted, which I overlooked. The fix was easy but then I didn't order the new PCBs immediately as I had a few more ideas to develop. That took its time and I placed the order right this week. Production is almost complete, I think the boards will be shipped tomorrow and there will be a lot to test then! I will change job, city and even country in about a month, so I really hope to manage to build and test everything before that, as settling down in the new context will definitely take some time and I won't be able to work on these things for a while.
On a side note, now I know the board fits inside the case nicely and it can be closed. I didn't measure the power consumption as I was sure it would have scared me! It seemed to work fine with the stock regulator anyway, but I didn't have anything else plugged in. Then I replaced the regulator with a 2A switching one just in case, and I think this board will just be one more reason to do that.
Hope to send another update soon  .
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