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h0trod

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About h0trod

  • Birthday 11/09/1975

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  1. There was one easy thing left to try. The FD1771 Floppy Drive Controller IC's are socketed. so I swapped the one from my good controller into my bad controller. No luck. I feel like I'm about to learn a lot more about floppy drive control signals, and get a crash course on how to use this digital oscilloscope..
  2. I spoke too soon. While the "repaired" disk controller seems to load programs OK from the drive, it does not save them properly. I generally get an I/O Error 66 after a save attempt. At this point, the Disk Controller LED remains lit. If I catalog the disk in DM II after one of these failed saves, I see a "program" with no name and a garbage "size" value. DM II disk tests, initialization, disk name all work fine. If I switch to my other working controller, I can save without issue. Beyond frustrated 😡
  3. After replacing the DSR ROMs.. it lives! Thanks a bunch to everyone in the thread for helping me work through the possible issues. It's very satisfying to see it work!
  4. Found some more dodgy solder joints and touched them up, and unfortunately I'm right back where I started. LED flashes at bootup. Stays lit and system hangs upon attempt to access the card (DM II startup screen or Extended Basic startup.) I have a set of DSR EPROMs I may as well try to install before I give up.
  5. Quick update, maybe getting somewhere. I replaced both the 74LS245 (again, and socketed it this time) and the the 74LS125. Still had the issue with the TI locking up at boot when the RS232 card is in. Removed all 74LS244s, RS232 behaves correctly. Trying one 74LS244 at a time, determined issue only occurs when a chip is installed in the center socket. Swapped around chips to verify it is indeed the socket not the chip. Found a short between two pins with the multimeter that I could barely see even with magnification. Good news: after fixing this, I no longer have issues with the card interfering with RS232. Bad news: still no sign of life from the card: not even the brief flash at power on. DM II gives me Disk Error 0. Will continue taking a close look at my solder job, and I have at least one spare for each of these chips and I will try some swaps. Will also try again to read ROMs. I may also replace the 5V regulator, despite it reading a solid 5V it gets very hot and has long since separated from the thermal paste that once upon a time sunk the heat, but I doubt this is the primary issue.
  6. An interesting thought, worth trying! And I did. I still get all zeros. I'm assuming the upper ROM starts at 0x5000 (20480 decimal). Since I don't think the card is being enabled, I'm not surprised by this result, but I appreciate the idea. I can almost type this XB program in from memory now 😂
  7. Yes, with the working card the test program works exactly as expected.
  8. Maybe I'm misunderstanding - but I think it must, or the program would be pointless, no? The program is linked earlier in the thread. FWIW, I got another disk controller card to try and it's working fine - so I suspect my problems are confined to the controller itself and not the PEB, firehose, etc. Still planning on doing my best to get the original card running, waiting on some parts.
  9. I have some ROMs on the way just in case. But the output from the XB test program that's supposed to read the beginning of the ROM contents has me believing that I'm not successfully reading the ROM, not that it's corrupted.
  10. Thank you. I appreciate your continued assistance! I have checked under magnification and tested adjacent pins for shorts and am fairly sure nothing is bridged. I have also begun checking every trace from the 245 and 244's to their destinations for continuity to be sure I didn't lose a pad or a trace in my soldering / desoldering efforts - that's still ongoing but so far I have found nothing. It's still possible I applied too much heat and damaged something downstream. I will try your suggestions.. I wish I had a local source for these parts!
  11. I have also confirmed that this is the same output I get when the card isn't even installed in the PEB. Not surprised, since when it is installed it's not "turned on" according to the LED.
  12. Yeah, I almost wonder if I made things worse with the chip replacements. The LED did flash at power on previously. We'll see what happens when I get the other Disk Controller card in. This isn't a project I want to throw too much money at. But I certainly want it working, and if I become convinced that the flex cable is the most likely issue, I'll pursue it.
  13. There are additional issues when the Disk Controller and RS-232 card are installed together. The RS-232 card works fine when the Disk Controller is not installed (to the extent I've already documented here.) But if both are in the PEB at the same time I get strange behavior. On my first attempt, I launched TE II and after going through the configuration screen, the TI immediately rebooted to the title screen. After shutting down and trying again, the TI won't boot to the title screen with both cards in, and the RS-232 led remains lit. If I take the Disk Controller back out, RS-232 worls fine again.
  14. No LED while running. Also happened to notice - it doesn't even flash briefly at power on.
  15. Progress, maybe. I replaced the three 74LS244s on the controller card, and attempted disk accesses no longer lock up the system. Any attempt to use Disk Manager to access the drive returns an instant "Disk Error 0". I was able to run the XB test program and it returned alternating rows of 0 0 0 0 0 0 0 0 . . . . . . . . So clearly I still have issues. I have another Disk Controller card on the way so I can compare behavior.
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