Mike's PCjr Page

After considering the 44-pin DOM discussed in a recent thread for my new jrIDE card, I concluded that getting the right 44- to 40-pin adapter in the right genders would be a little involved, so I found and bought this 40-pin 16GB DOM instead:

https://www.amazon.com/gp/product/B06Y4SWV1M

Although it comes with separate power wires to plug into a PC power supply, I found that it appears to accept +5v on pin 20 as well. This would make the power wire unnecessary so long as I moved the jrIDE jumper to provide +5v to that pin. I installed the DOM on the end of the jrIDE card (after a lot of online study to make absolutely sure I wouldn't get it upside down. Found plenty of IDE pinouts online, and confirmed things with continuity tests etc).

I then installed the jrIDE on the side of my PCjr's parallel port sidecar and started up the machine with a DOS boot diskette in A:.

After a screen with the IBM logo and color bar (reporting 640K), lines from the PCjr jrIDE BIOS appeared (reporting 112K base, 736K total memory). Then a couple of odd messages.

With the DOM installed but powered off, these lines appeared:

Drive 0:Not installed.
Drive 1:Not installed.

With the DOM installed and powered on, these lines appeared instead:

Drive 0:
Error! This drive is too old to support LBA access.

Drive 1:
Error! This drive is too old to support LBA access.

So -- does this actually mean this DOM is a no-go? Or can I try to format drive(s) anyway? I tried powering it both through pin 20 and through its separate power wires, and got the same results whenever it was powered on.

And also, just for my information -- I'm not clear on why two drives, 0 and 1, are mentioned. Does the jrIDE BIOS define two drives as existing there?

Just a follow-on thought. I noticed the discussion of LBA addressing here:

https://www.brutman.com/jrIDE/jrIDE.html

and it seems odd that the DOM I bought is flagged as not supporting LBA, since that page indicates that any drives 8GB or larger are required to do so. Or maybe that just applies to conventional hard drives, and not DOMs?

One other question. If in fact this DOM won't work on the jrIDE, I'd be interested if anyone knows where to buy a reasonably priced Kingspec 40-pin DOM with shipping from within the U.S. I see Kingspec mentioned favorably in other threads on DOMs here. All I can find on Amazon and eBay, though, is either high-priced (~$60-$70+ for an 8GB DOM), or ships really slowly from China, or both.

Is there a reason you are interested in a DOM over say a CF card with an adapter?

I have outfitted most of my older systems with CF adapters and they work great. The one I buy costs about $9 usd and then depending on the size of CF you want to use price can vary, but a 16 gig SanDisk CF is about $15 usd.

Both shipped from inside the US.

FWIW, half of the adapters and about half of the CF cards that I have don't work with the jr-ide. But, I have purchased three "approved" DOMs and none of them work.

Mike

Gremlin5 wrote:Is there a reason you are interested in a DOM over say a CF card with an adapter?

I was focusing on DOMs because I got the sense they were spoken of more highly in most of the threads I've looked at here. Not entirely sure why -- maybe lifetime write cycles? Or which are more likely to work with the jrIDE?

I'd be interested in giving a CF card and adapter a try at this point. But I'd really want to make sure that what I'm buying is known to work with the jrIDE. Do you have any links for the adapter you use? Given a choice I'd probably buy from Amazon if prices aren't too far off, because of their fast shipping. But eBay or elsewhere would be ok too.

It would also be great to know specifically which Sandisk CF card(s) work for you. I have drawers full of SD cards, but only one or two CF cards.

I'm fairly sure the DOM I'm using in my jrIDE is this one:
I could be wrong though. I'm hesitant to crack open the shell to check because the last time I did that I damaged it and I'd rather not risk more damage/repair.

Trixter wrote:I'm fairly sure the DOM I'm using in my jrIDE is this one:

Wow! Same make and very close model to mine:
The only apparent different is that mine is 16GB rather than 8GB. Also, the model number on mine is slightly different even from the pictures I posted above (which were from a product listing page); mine is DMV340S2I-016G-M013-B2. And, sadly, mine is reported by the jrIDE BIOS as not supporting LBA.

I'm curious why you guys are using such large DOMs? I have two jrIDE setups ..one with a 256MB Hyperdisk DOM and the other is 512MB. Both work great and I have a ton of software installed on both with plenty of space left over. Also, wouldn't the initial directory listing take forever on an 8GB DOM?

I'm using a large DOM because I'm developing TDL and you need at least 1GB to hold all software that can run on a PCjr (and 4G to hold it all uncompressed).

2GB is the max for 16-bit MS/PC/DR-DOS so my 8GB DOM is partitioned into C:, D:, E:, and a smaller F:. It takes about 50 seconds for the initial DIR on each of them, and then subsequent DIRs are normal speed, for reasons previously discussed.

My DOMs take 50 seconds for the initial DIR as well ... so disk size is apparently not a factor.

btw I installed TDL from another thread (with the 500 or so 1984/85 games included) and it works great! It only takes up about 30MB.