Mike's PCjr Page

Hi folks,
I'm getting near the end of my rope here. I finally got around to hooking up my jr-IDE after months of preparing and research. After checking both Mike's jr-IDE page and Alan's, I figured I would go with the Kingspec 8GB DOM (https://www.amazon.com/Kingspec-40PIN-M ... ngspec+DOM). Unfortunately, it didn't work. I plugged it in and got a message telling me the drive was too old to use LBA addressing, or something to that effect. So I figured maybe I got a bad DOM because when hooking it up to my laptop, it wouldn't show up either. Anyway, I figured I'd move on to using a CF card with an IDE adapter, the card being a Transcend 8 GB (https://www.amazon.com/Transcend-Compac ... dpSrc=srch). I've tested the card on my laptop and it does work, so I figured this was the way to go. Hooked it up to the jr-IDE, and once again, drive is too old to use LBA addressing, which I think is crap, but there was nothing I could do to make the jr-IDE recognize it. Anyway, rather than take another spin on the roulette wheel, I was hoping there was a place where there is a DEFINITIVE compatibility chart that shows what works, and what doesn't. I really don't want to blow any more money on buying junk that won't work. I know Mike has a small list on his page, but let's face it, that thing is one tiny list and those hard drives aren't very easy to get a hold of. Can anyone point me in the right direction? Or, if my problem is something that anyone has seen before, would anyone know what the solution is or if I'm doing something wrong? Thanks.

I think the short list you found might be the only list, plus a few reports scattered around these forums.

I have had luck with this Transcend 1GB DOM:
https://www.amazon.com/2KA3369-Transcen ... B00138PHV0

And another person reported this Transcend 4GB DOM works:
https://www.amazon.com/Transcend-4GB-Fl ... B00138NFDW

If those work, then the 2GB version probably will work and might actually be restocked on Amazon:
https://www.amazon.com/2GB-40P-Flash-Mo ... B00138PHVK

Hope this helps.

This one worked for me (although out of stock at the moment)

https://www.ebay.com/itm/2-piece-lot-SM ... 2749.l2649

OK, I'm an idiot. I wasn't supplying enough power to the CF. It works! But now I have another dilemma...after I formatted the CF under DOS 2.1 (the only DOS floppies I own), I am unable to read the CF card under Windows 10 (which I was kind of expecting to happen, but still held out hope) so I can copy all my disk images and whatnot over. Is there an easy way to get my CF to be recognized on my Win 10 laptop? Or is there some other piece I'm missing? Do I need physical copies of a higher DOS version with which to format the CF with? I had images of 3.3 and the patched 5 ready to load on the CF and write to a 5.25 disk, but I can't even get that far now

Generally, you boot the system and format the card with a patched MS-DOS 5 or 6.22, or IBM PC DOS 7 (ie. IBM PC DOS 2000). Then, run "fdisk /mbr" to lay down a new master boot record, then run fdisk and make one large 2G primary partition. (This should also mark it active, but just in case it doesn't, after fdisk reboots, go back and mark it active.) Once the system reboots off of floppies again, "format c: /s" to prepare the partition, then make sure to patch the newly-laid-down DOS on the CF card so that the PCjr can boot from it. You should be able to boot the PCjr from the jrIDE after that, and if so, you should be able to read that primary partition in Windows.

In Windows 7, this works for me, but I cannot see logical drives in any extended partitions, only the primary partition. I hear in the latest update to Windows 10, people are now starting to see the logical drives in the extended partition, which is good news.

So it absolutely needs to be a patched 5 or 6.22 in order for Windows to see it? 3.3 or 3.31 won't cut it?

No, it needs to be formatted with a patched DOS 5 or higher so that you can boot off of it on the PCjr. DOS versions 5 and later don't boot the PCjr unless you patch them.

DOS 3.31 is actually Compaq DOS 3.31 and I believe it needs to be patched too.

You want to stay away from 3.3 and lower because they only support partitions 32MB in size. 3.31 and later support 2G per partition.

Maybe I'm not wording this correctly. I'm not concerned about being able to boot the jr from the CF card, I can do that right now using DOS 2.1. I also don't care about the max partition size. Here's what I want to do. I want to format the CF card on the jr with a file system that will be recognized by modern versions of Windows. As of right now, I just have 2.1, and when I format the CF card in 2.1, the jr. sees it just fine, but when I take the CF card over to my Windows laptop to transfer files to it, Windows does noy recognize the file system and sees the card as unformatted. I thought I remember reading something somewhere that DOS 3.3 could format a drive as FAT, and it would be read on both the jr. and my Windows laptop. Is this not the case? Because right now, the only way I can get a hold of a patched 5.0 DOS disk, is to get it from the .img file I currently have on my Windows laptop. And if I can't transfer that from my laptop, to the CF card, and ultimately to the jr. to write to a 5.25 disk, it does me no good.

I have never tried to read a FAT12 partition in Windows. I have always used a FAT16 (ie. MS-DOS 3.31 and higher) partition, and that has read fine for me.

Awesome, that was the info I was looking for. Thanks, Trixter!