JrIDE and a CF card

[Kablamabam]

Maybe someone can explain what happened here because I certainly don't understand. All of a sudden I couldn't boot off the JrIDE anymore. After some preliminary troubleshooting steps I backed up the files and reformatted. No dice still wouldn't boot. Deleted and re-created the partitions with fdisk and that's when things went real wacky. I would get an unrecognized file system error and it wouldn't format. When running fdisk again it would list 2 Non-DOS partitions at 2 gigs each plus the 2 partitions I created, also Non-DOS. I found that really weird because the entire CF card is 2 gigs and here it was showing 6 gigs worth of partitions! Tried repartitioning/reformatting on all 4 of my CF cards trying different ways in different ways like don't make partition active, use or not use /MBR, different size partitions, etc... every time it would reboot and have the same non-DOS partitions.

I came across a post on a different forum that suggested I run this little program in debug:

mov ax, 309
mov cx, 1
mov dx, 80
int 13
int 20

So I did and it worked! Restored my backup and everything back to normal now! The poster said this little chunk of assembly wiped the partition table and speculated that partition table issues is what causes issues with the JrIDE and CF cards in general. I guess I Don't understand why fdisk isn't, or wasn't able to wipe the partition table when deleting/recreating partitions. IDK it has me stumped but I am glad to have things back to working now!

The post:
https://www.pcjribm.com/phpBB3/viewtopi ... bf2927662c

[Brutman]

Too much has happened here to tell you what went wrong, but it sounds like something altered your MBR (Master Boot Record) which contains the bootstrap code for DOS and the partition table.

FDISK /MBR can usually fix these things. In case of emergency there is a debug script you can run that will fill the MBR with zeros, which erases it but also unblocks FDISK from working with it. See Appendix A of "Patching DOS 5 for the PCjr" (https://www.brutman.com/PCjr/docs/Patch ... e_PCjr.pdf") for the script. That script is actually better than what you found, as what you found assumes there is an XT BIOS present. After that you run FDISK /MBR to create a proper MBR, and then patch for the PCjr if needed.

One last note - I couldn't read the content at that link because registration is required. I find it odd that somebody felt the need to spin up entire separate PCjr forum running the same software, with a similar structure, and then presenting a lot of the same original content that has been around for many years. Links like that should not be posted here unless they do not require registration to read them.

[Kablamabam]

A lot of that went over my head but I think I get the gist. Basically something jacked up the MBR in a way that fdisk couldn't fix. Last thing that happened was a game being launched and EGA graphics inadvertently being selected. Caused the system to crash/reboot and that's when the troubles began. I don't know what a bootstrap is but I think I'll look for an article explaining the DOS boot procedure and try to learn about it. The confounding thing for me is I had 4 identical CF cards and I guess just randomly picked the only one without a jacked up MBR. When I initially set up the JrIDE it went smooth with no assembly required. After it gets screwed up I find out that the other 3 CF cards were already screwed up in the same way. Weird.

I would like to make a patched DOS boot disk on my own too using a boxed copy of PC-DOS 5. The plan was to install it on a different machine and use that machine to make the patched boot disk because I don't think the install disk can be patched. Right? I have an 8088 PC and monitor, just need a CGA cable for it. I was holding out for an IBM branded one to pop up on ebay but I think I might just get a 9-pin serial cable instead. Its the same pinout so I guess that should work too. I'll pay close attention to Appendix A as I work through the how-to and I got 3 CF cards with issues to practice on

Sorry about posing a link I should not have. I was surprised to see another PCjr page out there too. I've googled PCjr stuff semi-frequently for 20-30 or so years. This site has always come up but I never came across that other one until last week so it's either a lot newer or hidden enough avoid popping up on google. I gotta say, though, the guy's PCjr setup is really impressive A triple stack PCjr with 3-d printed case parts, JrIDE and FDD emulator. A few other hardware mods I'm not familiar with too. Anyway apologies for the faux pas I will be more aware of any future links I share.

[Brutman]

No problem, and nothing for you to really apologize for. We just couldn't see the link ...

I wouldn't patch a DOS install disk. Install DOS somewhere, then make a bootable disk using format /s and patch that instead. (Never alter your master disks ...)


Mike

[Kablamabam]

Reviving this thread again - had the exact same scenario happen: Running some software that froze up and when I restarted got a non-system disk error. Used a boot disk and could still see the contents of the CF card but couldn't boot from it. Tried several things to no avail finally deleting, rebuilding, and formatting the partition which also didn't work. It's strange because the formatting works but when I try to copy things over (such as JRCONFIG.SYS) and run a directory I get a bunch of @ @ @ @ @ @ . @ @ looking things in the directory.

Another crazy thing I am noticing is when I reset as apposed to power off/on, fdisk will show a bunch of non-dos partitions that add up to more than the total size of the CF card! Thinking back I've always had trouble getting it to boot from the CF card from a soft reset (like ctrl-alt-delete) but would just turn off/on the system and it would work fine. Any thoughts?

Anyway I'm putting the Jr. on the back burner for now and will give this whole thing another go my next day off.

[jason]

Reviving this thread again - had the exact same scenario happen: Running some software that froze up and when I restarted got a non-system disk error. Used a boot disk and could still see the contents of the CF card but couldn't boot from it. Tried several things to no avail finally deleting, rebuilding, and formatting the partition which also didn't work. It's strange because the formatting works but when I try to copy things over (such as JRCONFIG.SYS) and run a directory I get a bunch of @ @ @ @ @ @ . @ @ looking things in the directory.

Another crazy thing I am noticing is when I reset as apposed to power off/on, fdisk will show a bunch of non-dos partitions that add up to more than the total size of the CF card! Thinking back I've always had trouble getting it to boot from the CF card from a soft reset (like ctrl-alt-delete) but would just turn off/on the system and it would work fine. Any thoughts?

Anyway I'm putting the Jr. on the back burner for now and will give this whole thing another go my next day off.

Hmmm, wish I knew more to help...any chance it could be something messing up the master boot record?

[Hargle]

Booting to a DOS diskette (To be safe,always use the same DOS version as what was on the C: drive) and typing "fdisk /mbr" should be the 1st step in attempting to resurrect a non booting C: drive. It is quick, harmless and might get you out of a jam of having to re-install everything from scratch.

It's troubling to me to hear how many times this has happened to users here. Could be virus related, but anytime software crashes there is always a risk of a stray write getting blasted out to the hard drive. This is something we could put a locking mechanism in the jrIDE BIOS to reject writes to specific locations on the HDD- many BIOSes have a feature like that and there's no technical reason we couldn't do something too.

[Brutman]

The flakiness here kind of makes me think there is a hardware problem.

• A timing difference on the jrIDE vs. the CF card.
• A faulty component, possibly due to heat as it warms up?
• A plain crappy component, such as a weak solder joint on the CF adapter or pins?

Here is a good example of marginal weirdness: I have hard drives that will not run reliably on the jrIDE with a classical 40 pin cable, but run just fine with an 80 pin cable. The combination of the jrIDE, cable and hard drive is the determining factor. My solution is just to always use the 80 pin cable to give myself extra margin.

Not all CF Cards and adapters are created equal. What brand of CF card are you using? I've always stuck to Kingston, Transcend and Sandisk.

[Kablamabam]

I got this issue resolved. The short story is I found a 64MB Cisco flash card to use and it worked out okay. I copied everything off the old flash card after it wouldn't boot and when I copied it back over to the new flash card it started acting flakey again. Not like booting issue but corrupt directory listings with @@@@.@@@@ and some programs working some not. For example RTC.COM worked just fine from the backup but EDIT.COM did not. After another format I copied some stuff over from another backup I had taken much earlier and no issues there. So I guess the original 2GB Sandisk was the issue? for whatever reason I don't know but it seems to work fine in everything else I have and it worked for a couple years with the JrIDE too.

Oh and the soft boot thing is still an issue with the Cisco card too. The drive won't even be detected on a soft boot and the drive activity lite stays illuminated. Power cycling resolves the issue so I just don't soft-boot anymore