Mike's PCjr Page

Hargle wrote:There are adapters o' plenty that can convert SATA and 40/44 pin ATA devices to USB.

Thanks! 40-pin IDE to USB would be very handy in my case.

Brutman wrote:DOMs that are female are designed to plug straight into the motherboard. The USB adapters are female too, as they expect you to be plugging in a drive with pins on it. There are cables for this; you just need to be aware of the pinout and ensure the pins go to the right row.

I noticed this issue with my 40-pin DOMs and some ribbon cables I had around. Ordered some of these to try:

https://www.amazon.com/gp/product/B003PU1EVG/

That's a trap!

You actually want this ... https://www.amazon.com/gp/product/B00JSYDCK4

(Note: that's the 44 pin version ... you might want the 40 pin version depending on what you bought.)

Note the cable; it is not just plumbing the pins straight through; it is swapping rows 1 and 2. Draw it out on paper and you'll see why you need to do that.


Mike

Brutman wrote:That's a trap!

Now that you mention it, I immediately see why -- no diagram required.

Thinking maybe this would work:

https://www.amazon.com/CablesOnline-40- ... 00G0174IO/

Pins aren't as exposed, but I think/hope the DOMs and ribbon cable connectors won't have any issues getting into these.

Thanks for straightening that out!

Franko wrote:Sorry for a tangental question, but how do you connect a DOM to a modern machine?

I purchased a female to female IDE adapter. I plug it straight in to my IDE cable on my desktop box. I cut/bent the key pin on the adapter on one side since my desktop IDE cable has the pin hole filled.
https://www.amazon.com/gp/product/B00G0 ... UTF8&psc=1

I ended up hooking my jr floppy drive to my desktop, and after a lot of playing around I got it to start reading/writing to the 360k floppies properly (I booted to an incompatible DOM which I installed DOS 6.22 on and preloaded with all the floppy images and Mike's DSKIMAGE utility). Then I wrote the PC-DOS 3.30 images to a pair floppies, reconnected the floppy drive to the jr, and was able to boot to PC-DOS from floppy. Upon running FDISK, I saw some strange partitioning (could be a result of MS-DOS 6.22 2GB partition), and the first partition was labeled non-DOS. I tried to delete everything, but couldn't, and ended up using DEBUG to wipe the partition map (see the below URL for reference).
http://www.after10.net/Debug.html

After that, I was able to use FDISK to create the 32MB partition at the beginning of the disk, format it, and copy the DOS files over from the floppies.
Now my jr boots to DOS!

Now, I prefer to run DOS 6.22 because I'm more familiar with it, but perhaps the memory size "patch" isn't doing what I expect for some reason. I suppose the next step is to see if I can find a 360k DOS 6.22 floppy set (I think I have an upgrade floppy set) and try to format the drive ON the jr and see if that makes any difference.

In the end, I can report that the 16GB Kingspec DOM (https://www.amazon.com/gp/product/B00ZY ... UTF8&psc=1) is indeed bootable on the jrIDE.

Glad you got it working, and that you've finally found a DOM that works!
DOS 5.0 is a good substitute for 6.22; that's what I run on my PCjr. It'll get you 2GB partitions and is compatible with disks made with 6.22, which is what I run on my 486 machine. Both 6.22 and 5.0 seem to be compatible with modern OSes, so all the machines in my office can play well with each other.

Not that you'd want to do this whole DOM prep thing again, but since you're a pro at it by now, I do suggest trying 5.0.

Thanks Hargle. I have no problem using DOS 5, and after posting I realized I should check...I might have DOS 5 360k floppies around here somewhere...I need to check on it.

Is everyone using PC-DOS 5...or is MS-DOS 5 also known to work properly with the memory detection patch?
Also, will DOS 5 load WITHOUT jrconfig installed/setup (as in booting from a floppy disk)? I realize jrconfig is needed to get optimal memory usage...but if I don't need it to boot the floppies, I won't bother with it.

I was also successful in installing and booting DOS 3 on the SD card adapter:
https://www.amazon.com/gp/product/B00DG ... UTF8&psc=1

I also used a standard PATA IDE cable along with this 44-to-40 pin converter:
https://www.amazon.com/gp/product/B0000 ... UTF8&psc=1

Maybe worth noting I used a 4GB micro SDHC card. I note that since SDHC all can use block addressing, which is more similar to LBA.
Not sure that it matters, but I thought I'd mention it anyway.

Will tackle the DOS 5 thing another day...