#debugging

[poast-bot]

"de bugging" code ? why would you want to do that ? i like the bugs

[unbfacts]

Rubber duck debugging is a technique programmers use to find errors in their code. Explaining the code out loud to a duck or any inanimate object helps them spot issues as they talk through each step.

[posthumanwanderings]

Virtual-On Oratorio Tangram hidden debug mode w/Code Breaker Code: 00CF9F58 00000001 found via Sega Bass Fisherman

[techav]

Moving Slowly, but Still Moving

I've not said much about the new modular phase 2 PCBs I made for my PikaPC project since they arrived. Well, that's because they're still not working and I can't figure out why.

I was able to get some signs of life out of the host card. It did appear to be running code at least, but it was never able to boot to the PPC Forth prompt. Such a disappointment after how easily I was able to get it running on the prototype. I ended up setting it aside while I worked out the bugs on the video card, picking it up now and then whenever I learned something new about my bus timing or how to properly terminate bus signals. Nothing seemed to help. But I did find some errors in my design, such as completely omitting necessarily pull-up resistors on shared bus control signals.

Of course I had no idea if it was my host card or the DRAM card that was preventing it from running properly. Too many variables when trying to simultaneously troubleshoot two boards, neither of which have been confirmed to work properly.

I decided to pursue a couple different avenues.

First, I designed a new card that could hold up to 2MB of SRAM. The logic is much simpler for SRAM than for DRAM, and I thought I might be able to use it add memory to my prototype as well.

Second, since I already needed to make some revisions to my host board, I decided to squeeze in a couple 1Mx16 DRAM chips wired to the PPC403's built-in DRAM controller. This memory would be on the CPU's local bus instead of my expansion bus, so it would eliminate some of the variables for troubleshooting.

I got the SRAM board assembled first and tested it with my prototype. It appeared to work first try — I could write values to random memory addresses and read them back without error. Next I tested it with my (now heavily-bodged) first draft host card. Exact same behavior as I was seeing with the DRAM card.

So I assembled the new host card. This time I was met with … the exact same behavior again.

Disheartening.

It is running code up to the point of starting the PPC Forth cold start routine, so I know the CPU, clock, reset, and ROM are functioning well enough. But never gets past that point. I have identified a problem with it enabling machine exceptions during initialization, but even bypassing that step, it still doesn't make it though cold start. It's looking like main memory still isn't working … which is what I was hoping to avoid by adding the on-board RAM to the new host card.

I need to do some more work with the logic analyzer to confirm it is properly addressing main memory and that the DRAM RAS and CAS signals are behaving as expected. It could just be I have misconfigured the PPC403 bank registers that define how it accesses memory.

I was hoping to have the modular system running in time for VCF Southwest. The show is next week, so I'm pretty much out of time. But until then I'll keep probing away at it in the hopes that I'll finally have a breakthrough.

If you're within range of Dallas / Fort Worth airport, come check out VCF Southwest next weekend, May 29-31, 2026. I will be there — alongside over a hundred other exhibitors & vendors — with my Wrap030 project, my PikaPC prototype, and, with any luck, my phase 2 PikaPC system.

[farronking]

Some days are like this :D

[pressplay-if]

I’ve noticed with the siblings background MC when you give them different names they still show up at Linda and Elliot is that a bug or intentional <:D

OH DAMMIT DAMMIT DAMMIT

...needless to say from that reaction, it's not intentional

[frog707]

debugging my office

Tonight I got distracted by a fly buzzing around my office. I guessed the root cause: flies are attracted to light, and my office was the only room with lights on. I tested my hypothesis by turning off the overhead light in my office and turning on the one in the hallway. In support of my hypothesis, the fly flew into the hallway. I then toggled the lights and closed the door.

Now there's a fly in my office again. I'm unsure whether it's a different fly. It could be the original fly bypassed the door, perhaps while I was fiddling with the lights, a known race condition. So now I'll repeat the process...