Mike's PCjr Page

I turned on my PCjr that has a jr-IDE and DOM attached. It didn't find the DOM. I have had that before. Wiggled the power connector and then it found the DOM. But right after it finds the DOM and fails to find a second device, it prints ERROR and stops. Any ideas about what might be wrong? I haven't put any effort into this yet so I don't know what the display on the jr-IDE is reading. It would be nice to create a clear shell for this sidecar so you could view the LED and POST display without taking it out of the shell.

Is there a way to bypass the jr-IDE BIOS and boot to floppy so I can use tools to look at the DOM?

It does not look like there is a method to bypass the BIOS at startup. That was something added into a later version of the BIOS that never made its way over to Mike.
I assume the "ERROR" message you're reporting is actually "Error! This drive is too old to support LBA access."?
That is the #1 message printed when the BIOS cannot communicate at all with the drive, which brings us back around to your power connector wiggling causes some behavior to change, so that is the place to start investigating for a bad connection.

No, it is just ERROR. Last night I noticed that the floppy drive light comes on but I doesn't spin or seek. I think the floppy drive isn't getting power or has failed. Since I keep having problems with the DOM sometimes losing power, I am going to look at the Y-cable that is powering the DOM and floppy drive. I think spreading the ends of the male connectors may fix it. I will post the solution here once found. I think the jr-IDE BIOS is looking to see if there is a bootable floppy in the drive and aborting with an error out when it can't access the drive.

Interesting. Unless Mike added messages to the jrIDE BIOS that I'm unaware of, there's nothing in the jrIDE BIOS that says "ERROR" with no other information, and definitely nothing in all caps like that.

I think you may be onto something with the floppy issue. Don't forget about those built-in PCjr diagnostics! I've never actually used it to diagnose a problem before.

OK, it was definitely a power issue to the floppy drive. The first thing I did was to just connect the floppy drive, taking the y cable out of the setup. Not only did that get rid of the error, but the DOM is still active! Apparently the DOM is also able to pull power from the jr-IDE directly. So now we know what getting an error like this means. I also found another issue, but I will start a new thread for that so searches will work.

Hargle wrote:Interesting. Unless Mike added messages to the jrIDE BIOS that I'm unaware of, there's nothing in the jrIDE BIOS that says "ERROR" with no other information, and definitely nothing in all caps like that.

I think he's seeing the PCjr BIOS POST "ERROR" string. The full string should have had a letter or something after it.

I think maybe, if I left it on longer, I would have gotten the rest of the message. It seemed to be locked up, but maybe it was just retrying the floppy.