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Re: Troubleshooting - I'm Stumped! Help, please?
Posted: Mon Nov 11, 2024 5:25 pm
by DRG
I've been messing with computer junk for nearly 55 years and am still learning.
That's impressive. I'm no spring chicken myself either, and I don't subscribe to the "you can't teach an old dog new tricks" mentality as I'm always willing to learn something new - even at my age. Maybe it just doesn't stick the first (or second!) time around.
The way I look at it is that this knowledge I'm gaining from the forum is a different kind of investment for my retirement.
Re: Troubleshooting - I'm Stumped! Help, please?
Posted: Mon Nov 11, 2024 8:07 pm
by BigDumbDinosaur
I've been messing with computer junk for nearly 55 years and am still learning.
That's impressive. I'm no spring chicken myself either, and I don't subscribe to the "you can't teach an old dog new tricks" mentality as I'm always willing to learn something new - even at my age. Maybe it just doesn't stick the first (or second!) time around.
The way I look at it is that this knowledge I'm gaining from the forum is a different kind of investment for my retirement.
My wife often wonders why I still mess with this stuff at my “advanced” age. My explanation invariably is it is good for my mental health, which then starts a mutual insult session about my and her mental states. 
More seriously, there is some scientific conjecture that the deep thinking needed to do such things as write a book or compose music may be doing for the brain what aerobic physical exercise does for the heart and lungs. If that is the case, the thinking and planning needed to design and build a home-brew computer and write software for it should keep one’s brain as fit as a fiddle as old age creeps up.
In my case, however, my brain is only as fit as a viola. 
Re: Troubleshooting - I'm Stumped! Help, please?
Posted: Sat Nov 16, 2024 12:23 pm
by DRG
That's quite apt, as I am actually a Dave!
I'm going to stop here, abandon this current build and start a thread on the rebuild but setting out my aspirations so I can get group input on the correct way to proceed, rather than engaging the group in diagnostics and troubleshooting - which may be the source of my current woes: I have a design destined to always have problems.
Re: Troubleshooting - I'm Stumped! Help, please?
Posted: Sat Nov 16, 2024 10:14 pm
by BigDumbDinosaur
That's quite apt, as I am actually a Dave!
What a coincidence!
BTW, that cartoon came from a musician friend of mine whose name is Dave. Amusingly, he doesn’t play the violin or viola, or any other stringed instruments, for that matter. His primary instrument is the trombone, which I like to remind him is the loudest of the brass instruments. That’s why the trombones are placed in the back of an orchestra—so the conductor doesn’t suffer hearing loss, or get blown off the podium.
I'm going to stop here, abandon this current build and start a thread on the rebuild but setting out my aspirations so I can get group input on the correct way to proceed, rather than engaging the group in diagnostics and troubleshooting - which may be the source of my current woes: I have a design destined to always have problems.
Interesting you’ve decided to do that.
So far, I have designed and built four working examples of my POC V1 series contraptions. In each case, I worked out all aspects of the design “on paper” before even drawing a full schematic or doing a PCB layout. By doing so, “sleeping on it” for a few days, and then revisiting everything, I was able to catch errors—most of them, anyhow—prior to commencing a build that would have potentially fatal design problems. This procedure became especially important starting with POC V1.2, which was equipped with four TIA-232 channels in two DUARTs, which measurably added to circuit complexity and chip count (and increased firmware complication, especially in the IRQ handler). This isn’t to say that errors didn’t creep in now and then. However, I was largely able to avoid use of bodge wiring to fix things—POC V1.0 was the only one that needed bodging to be made operational.
The other thing that I and others around here recommend is to be realistic with your design goals. The greater the complexity, the greater the odds that you will have problems in getting it to work. Also, an idiosyncratic memory map usually means dense glue logic, increasing the odds of unanticipated problems, as well as constrained performance due to too much gate delay.
Bottom line is to keep your first try simple enough that you can troubleshoot it in a reasonable amount of time, and with the test gear at your disposal. In other words, learn how to fly a single-engine plane before you climb into a 747’s cockpit and take off for Tokyo.