New to jrIDE - DOS version? CF or DOM? 3.5" drive?

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New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby EEBuckeye » Wed Dec 03, 2014 6:50 am

I was lucky enough to get a jrIDE for my 'new' PCjr and any help you could give would be appreciated!

1) Which DOS version is recommended?

2) I would like to use compact flash so I could transfer files easily from my PC. Is this difficult to install/use?

3) If CF is ok what IDE/CF adapter and CF card is recommended?

4) If I use a DOM how do I transfer files to it since I do not have a 5.25" drive?

5) Can I use a 3.5inch drive on a parallel port expansion card? Where could I get this drive? I did see one on eBay but was unsure if it would work.

Thank you!
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby Hargle » Wed Dec 03, 2014 9:49 am

some answers:

1) most of us seem to like DOS 5.0
It will need to be patched to use on the PCjr, instructions and even a utility to do it for you are here on this forum if you poke around some.

2+3) I'm only using DOMs so I can't suggest which one works. CF to IDE adapters are easy to source on ebay.

4) I attached my DOM to a USB->IDE converter and moved all of the files I'd (hopefully!) ever need onto it in one afternoon using my modern machine.
Before did the bulk file upload, I fdisked and formatted the DOM on the PCjr and verified that the DOM was working properly and bootable.
I have several 'tweener machines with 5.25" drives so if I ever need to get additional files on there, that's the route I will take. I realize that doesn't solve your problem, unless you'd like to buy a 'tweener machine from me. :)

BTW: congrats on getting an IDEjr. it will change your life.
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby EEBuckeye » Wed Dec 03, 2014 11:01 am

Thanks! I did not even think about a IDE to USB adapter to move files to the DOM.

I guess I plug in the DOM and boot the PCjr and it seems the new drive but needs to be formatted, etc..
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby Brutman » Wed Dec 03, 2014 9:31 pm

Some other answers ...

1) I've used DOS 2.1, 3.3 and DOS 5 on my jrIDE. DOS 2.1 is a waste of time - do not install it. DOS 3.3 is reasonably good, runs well on the PCjr, and with the magic of extended partitions you have many 32MB partitions for data. DOS 5.0 needs to be patched and it has an irritating pause when computing drive free space, but it allows you to use much bigger partitions.

I have a utility that I wrote that behaves like a boot manager. It lets me switch between DOS 3.3 and 5.0 on the drive by hiding the partition that is not active. That way, all of the other drive letters with the data on them do not move.

2/3) I have no experience with CF. I like spinning rust hard drives - they seem more authentic. DOMs are designed for this application and should be more durable than CF, but then again with the way these machines are being used I think that CF is probably more than adequate. Not all CF cards are created equal, so find one that works with XT-IDE.

4) You need a "mothership" system - something that has all of the drive types on it. I use a 386-40 for that. There are lots of options.

5) Yes - the Backpack drives work fine. Except the drivers come on a 3.5" floppy disk, and you need to boot with the driver in your CONFIG.SYS file. And obviously, you can not boot from a drive on the parallel port. They are also fairly slow. But yes, it works for basic data transfer.
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby EEBuckeye » Thu Dec 04, 2014 5:41 pm

Can I install DOS from my PC to the DOM or CF by creating 3.5 DOS disks from image files I have?
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby Hargle » Fri Dec 05, 2014 8:31 am

Maybe.
If you were to hook up your DOM using a USB adapter, it is possible that a windows based USB format tool (HP makes a popular one) might be able to create a FAT partition and read DOS files off a floppy disk and that DOM might actually be bootable on your jr when you attach it. There is a lot of planetary alignment that would have to happen to get it to work. Remember too that if you're going to use DOS 5.0 it has to be patched first or it will not boot on the jr.

Otherwise, if you were to attach a DOM directly onto a motherboard's IDE controller and boot to a 3.5" disk, as long as the DOS you've booted to can "see" the DOM and fdisk+format it, that probably has a better chance of working than doing anything in windows.

This is part of the magic/appeal/frustration of working with vintage machines. Good luck on your journey.
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Re: New to jrIDE - DOS version? CF or DOM? 3.5" drive?

Postby Brutman » Sun Dec 07, 2014 5:14 pm

There are a few things that have to be done to make a bootable hard drive image. Lets assume DOS 3.3 and you are on the PCjr to keep things simple.

  • A DOS 3.3 partition needs to be created.
  • The DOS 3.3 partition must be marked as bootable
  • The boot sector needs to have the bootstrap code sequence
  • DOS must be installed from floppies. (The hidden files need to be in a specific place.)

Under normal circumstances, DOS FDISK takes care of the first three. Sometimes the partition is not marked as bootable; FDISK can take care of that. Sometimes the bootstrap code is missing from the master boot record. When that happens the FDISK command with the /MBR option can be used to rewrite it. (That might not be true for DOS 3.3 - that might be a DOS 5 ism.)

If I had to do this without being on the machine (due to a lack of floppies) I would experiment with VirtualBox, VMWare, or QEMU. All of those can emulate a machine. You can install DOS into a virtual machine. Then you can experiment with moving the virtual machines hard drive to the DOM using a USB to IDE adapter.

Virtual machine hard drives are not raw block devices. So there is probably an import or export utility. You should be able to find that easily. Getting that raw block level image onto the DOM is the trickier part. You need to make sure you have a good MBR and a good partition on it. The Linux DD command can do the movement of data; I'm not sure what people do under Windows.

If you decide to do it this way, write up a how-to ... it would be helpful to others.
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