Hello Michau, > Controller/drive initialization failed > But what is really interesting, and what I have completely overlooked > the first time, is that when I select drive #0, the first error > message I receive is actually not a Timeout, but a Read error (on > block 0x00000002, whatever that means). So you mean the message above is a "drive initialization failed" and not a "controller initialization failed". This is a good idea! > Which leads me to this possible theory: maybe the drive is OK, and the > controller is OK, but the drive is simply not formatted? Which > explains the first read error. If i remember correctly the data lines from controller and drives are differential lines with a terminiator. Did you checked this termininator on both sides? > Then the computer tries do "something" > with the drive, which results in timeouts If the data lines are broken or the disk isn't formated, no marker can read. This can issue a timeout. > So, now the big question is: how to format the drive. From what I read > about MFM drive controllers, each of them can have a different > low-level format, not interchangeable with other controllers. Yes that's true. > The > controller here is WD1003-CMD, with some custom DMA channel > interface. Would it use the same format as a PC-compatible ISA > WD1003-something controller? All hard disk controllers have tolerance, so they are not 100% interchangeable. In the 80, when a ship data with hard disks, i put the passed controller with the hard disk. Martin > W dniu 2014-08-09 20:15, Michal Pleban napisal(a): >> Hello! >> >> I am back home, and I tried to fix the broken C900. Three RAM chips >> needed replacement, I exchaged them for new ones and the computer >> again boots normally. >> >> I disassembled the hard drive and there were no fuses inside, but >> after I rotated the drive by hand a few times and reseated all the >> connectors it started to spin again. After I assaembled it back it >> stopped spinning, so I repeated the process and it now spins >> properly. It looks like some kind of mechanical problem. >> >> Anyway, the computer is still not able to communicate with the drive. >> All operations result in timeout. I tried these solution: >> >> * Select all four "drive select" DIP switches. >> * Use another data connector on the controller. >> * Play with the undocumented first DIP switch. >> * Play with the "Set drive type" option in BIOS; apparently the >> option 2 is for 20MB disk. >> * Use "Park drive 0" and "Park drive 1" commands from BIOS. >> >> All I get is only a bunch of timeouts on every oepration (seek, >> reset drive etc.) >> >> Here are the theories I came up with: >> >> * The controller is dead. That doesn't seem to be the case, as >> removing the controller gives additional error message >> "Controller/drive initialization failure" which is not present when >> the controller is inserted. So there must be at least some >> communication between the computer and the controller. >> >> * The controller is partially dead. Maybe exchanging the ASIC chips >> with another WD1003 would help in such case, but all WD1003 PC >> controllers I found on eBay have the chips soldered. I wasn;t able >> to find a WD1003-CMD anywhere for sale, only WD1003-WA? ISA cards. >> >> * The drive is partially dead. I guess timeout issues would rather >> indicate errors on the PCB and not the drive mechanics. On the other >> hand, the drive is able to perform self-test and flash the LED, so at >> least it must be partially working. Maybe some chips related to the >> MFM interface are dead. Exchaning the PCB with another Miniscribe >> 3425 mught help here. If MikeS' offer to do that still stands, I >> would be glad to take it. >> >> * The computer is able only to communicate with select types of MFM >> disks and the 3425 is not one of them. This seems unlikely, as the >> WD1003 controller is pretty standard ans there should be no reason >> for some special kinds of disks to generate timeouts with it. >> >> Any other ideas would be welcome :-) >> >> Regards, >> Michau. >> >> >> Message was sent through the cbm-hackers mailing list > > Message was sent through the cbm-hackers mailing list Message was sent through the cbm-hackers mailing listReceived on 2014-08-22 13:00:42
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