The 486DX-50 project – part 3: The storage solution

The CF card issue

It bugged me that I couldn’t get the CF card to work. I read online that it probably had to do with resetting the MRB. But that could only be tried while booting from a floppy with the CF card as the only connected harddisk. That was a problem, because the PSU only has one floppy connector and I don’t have a Molex to floppy adapter cable. I solved this by powering the CF to IDE adapter with the PSU of another PC.

Booting from a floppy didn’t prove easy. I had already tried to replace the floppy drive with a Gotek, but that didn’t work. I tried formatting floppies but that didn’t work either. I suspected a faulty floppy drive, but I didn’t have a replacement on hand. I tried it with the Olivetti 386 PC, but because I had taken that apart, I refused to boot, due to a locked keyboard message. As there is no keyhole on the case, there’s probably a connector on the motherboard somewhere. But that’s an issue for another time.
Then I remembered that I also have a Pentium IV system that has Windows 98 on it and has a floppy drive. I succeeded in formatting at least one of the few floppies that I had lying around (about half of them gave errors) and that let me boot up the 486!

I reconnected everything for the millionth time which wasn’t easy because the IDE connector on the CF to IDE adapter is very tight (I broke a bit of plastic on the connector when I first inserted the cable.) I was lucky to recover the tiny jumper cap that I also switched for the millionth time. And then I ran FDISK /MRB. That didn’t seem to do anything, so then I ran regular FDISK. That allowed me to set the first partition as active and voila: The CF cards boots up! Yeah!


I did all this primarily to have a quieter system as the old IDE harddisk made a lot of noise. The only other source of noise comes from the PSU. I opened it up and cleaned it out, but it wasn’t too dirty so that didn’t do much. I’ve ordered a new 80mm fan and hope that that will make it quieter. I didn’t remember which way the fan blew though, so I choose to let it blow air out of the system. I don’t know if that is right though. I guess we’ll see.


I also made some pictures of the RAM and cache chips in case I want to add some memory or replace them.

Now what?

Now that this works, I guess I’ll see if I can get it properly installed in the case and if it also works with the CD-ROM as slave. I’ll probably need some extension cables. And I’ll need a extra floppy power cable. I’ll also need to connect the audio from the CD-ROM to the sound card. And I’ll keep my eyes out for a VLB video card, probably a Cirrus Logic CL-GD5424 or something like that. And I’ll try to order a Gotek. And a case badge…

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