More Hardware Woes
After my earlier hardware glitches were seemingly resolved, I added the RAM to BMOW, which is the last of the basic hardware components needed. Unfortunately, this created a huge new set of hardware problems that I can only describe as “everything’s broken.” I haven’t even attempted to use the RAM yet, but its mere presence in the system (and the wires connected to it) seems to have caused everything to go haywire, and now the old “BMOW is alive!” program no longer works at all. I haven’t had time to really nail down what’s going wrong yet, but there are so many signals that suddenly seem to intermittently get the wrong values, I feel like my whole house of cards has just collapsed.
Update: A ROM was loose. D’oh! BMOW is alive, again.
4 Comments so far
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Steve,
Don’t give up. We are rooting for you and BMOW.
My guess is that the extra capacitance of the RAM wiring and loading is stressing the limits. Does it work with the RAM chips removed? If not, maybe you can remove the wiring and wire up a connector of some sort, just to allow you to connect the RAM a bit at a time, I mean one data or address bit at a time.
Thanks for your kind words. I actually feel very silly right now, because I missed checking the obvious stuff before jumping to conclusions. It turns out that one of my micro-ROMs simply wasn’t pushed all the way into the board. Since I had the board flipped upside-down to get at the wire-wrap pins for the logic analyzer, I never noticed. I probably spent 10 hours over several days, painstakingly hunting gremlins in the wires, when all it took was a push of my thumb on the ROM to get everything working again.
Note to self: get better ROM sockets.
I know exactly what troubleshooting for days to find a small problem is like. I’m glad its all working now!
Too bad there is no save menu in real life :-/
Better analogy: Undo key in real life