How do you create a bootable DOS disk from...

[Sharkey1331]

Hi all,
So, here's my setup:

1) PCjr, with working stock floppy drive. Can't find my discs. Pathetic, yes, but, it happened!
2) 486 computer, with working CDROM, plus HDD, 1.44 and 360k floppy drives. I call this machine "The mothership" because it can speak old computer and new computer! It is running DOS 6.2x, and also Windows 3.11.. It also features a ROM burner- but this is irrelevant here!
3) Modern computer, running Windows 10, with DVD/CD reader/burner drive, internet, etc.. This is what can go and get stuff off the web. I have downloaded IBM DOS 3.30 and also IBM DOS 2.10 .img files.

How do I create a 3.30 startup disk for the PCjr, using what I have above? I guess if I could find a program that can read/extract .img files, I'd be able to burn the individual files to CDROM, then put that in my 486, put a blank floppy in the 360 drive, and perhaps some format commands can be used? Or would that only work if I am able to somehow boot the 486 onto the same version of DOS I wish to format the 360 floppy with?

Jason

[Sharkey1331]

Ack- replying to my own thread! I don't have all the answers, but figured out some more stuff...

With my windows 10 computer, I mounted the .img files of each disk image using dosbox. I was then able to mount a new directory (which mapped to just a normal directory on my Windows 10 HDD) and copy *.* of the files in each .img to that directory, so now I can access/have extracted the files (in theory)..

I think I could burn these to a CDROM. Is it as simple as just putting the files on a 360 floppy using the 486, and then "Bob's your uncle"?

[monzamess]

Try Mike's "dskimage" program on your 486 to write out the .img files to 360k floppies. If it's a true 360K drive you should be good. If it's a 1.2MB it's less likely to work, but could.

https://www.brutman.com/PCjr/pcjr_downl ... l#DskImage

Extracting the individual files as you've done and just writi ng them to a formatted 360k won't make a bootable disk.

The process above will produce a bootable disk.

Alternatively, you can create bootable disks from DOS using "format /s". However that will create a bootable disk for that version of DOS (i.e. if you created one from your 486 it would boot DOS 6.22 which is not compatible with the jr). So this only helps you if you can already boot the computer into the desired version of DOS... Kind of a chicken-and-egg problem.

[KenG]

Download Mike's DSKIMAGE.ZIP from his PCJR page. Extract it and you will have dskimage.exe and dskimage.txt. Read the text and then use it to burn the image to a 360k disk. Once you have this working, you can get a lot of software by downloading image files to a modern computer. Others here can also send you images via email.

[Chuckphd53]

Jason, let me know I can send a boot,disk if all else fails...
You have my email, just let me know...
chuck

[Brutman]

Don't "mount" an image file with Windows. That is good for looking at files but it doesn't preserve the structure of the diskette or image that you mounted. In particular the layout matters, as do things like the first sector (the master boot record).

You have all of the pieces that you need. The DSKIMAGE program (pointed to previously by others) can either save a diskette to a file or write a diskette from a file. The important thing is that all of the diskette is written, including the boot sector and the unused portions while the structure is preserved. With a program like this you can make (or save!) diskettes.

Not all disk images are created the same way. I prefer raw, sector-by-sector copies with no meta data and that's what DSKIMAGE expects. Some programs like WinImage include meda data. You should be able to convert those other programs to a normal, sector-by-sector version that DSKIMAGE can use.

The nice thing about those diskette images is that they can be used with virtual machines too.

[Sharkey1331]

DSKIMAGE worked perfectly! Thanks so much guys!

Jason