XT-IDE on PCjr

Hardware questions and modifications

Re: XT-IDE on PCjr

Postby GHiero » Thu Feb 13, 2014 4:03 pm

Is there any way to shorten the boot time with the jrIDE? It looks for a master and a slave device on the IDE port, but if you only have the master present, can you tell the BIOS to skip the slave detection? Is there a way to eliminate the floppy drive seek when booting to the IDE card?
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Re: XT-IDE on PCjr

Postby jmetal88 » Thu Feb 13, 2014 10:42 pm

You can skip the floppy seek by pressing Escape to view the boot menu and C to boot from the hard drive without checking the floppy. You have to do this twice with JRCONFIG.SYS installed, as the BIOS presents the boot menu again when JRCONFIG forces the soft reboot to update the memory count. I don't think there's a way to skip checking for both hard drives.
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Re: XT-IDE on PCjr

Postby monzamess » Sat Feb 15, 2014 3:44 pm

Finally had some time to try things out. Got out my 128K PCjr (with the larger PS board), plugged in the speech adapter, parallel port, then the jrIDE.

On POST, the jr sees 640K. On boot, the jrIDE BIOS comes up. Now I'm at the point that it does not recognize my hard drive, or maybe, it's just not compatible. It's a WD800 (Western Digital 80GB IDE) and claims to be LBA on the sticker. However, jrIDE identifies it as "Drive 0: └└└└└└└└└└└└└└" and then says it's too old to do LBA.

Do you have any suggestions on things I can try? Is this behavior consistent with a bad IDE cable? The only other IDE drives I have to try are CHS.
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Re: XT-IDE on PCjr

Postby jmetal88 » Sat Feb 15, 2014 4:53 pm

monzamess wrote:Finally had some time to try things out. Got out my 128K PCjr (with the larger PS board), plugged in the speech adapter, parallel port, then the jrIDE.

On POST, the jr sees 640K. On boot, the jrIDE BIOS comes up. Now I'm at the point that it does not recognize my hard drive, or maybe, it's just not compatible. It's a WD800 (Western Digital 80GB IDE) and claims to be LBA on the sticker. However, jrIDE identifies it as "Drive 0: └└└└└└└└└└└└└└" and then says it's too old to do LBA.

Do you have any suggestions on things I can try? Is this behavior consistent with a bad IDE cable? The only other IDE drives I have to try are CHS.



Hmm, I'm not sure. It does sound a bit like what happened when I was testing the first jrIDE I soldered up (the one I sent to Bill), but after I unplugged and re-plugged things a few times, it stopped doing that. The biggest drive I've tested them with was 40GB, though, and I had a jumper set to limit it to 32GB of usable space.
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Re: XT-IDE on PCjr

Postby monzamess » Sat Feb 15, 2014 7:43 pm

Lacking other options, I tried my 6.5GB CHS drive, a Seagate ST36531A.

jrIDE recognized the model. I booted using a DOS 3.3 floppy. According to FDISK there was a single non-DOS partition filling the drive so I used the instructions here: http://support.microsoft.com/kb/106419 to use DEBUG to wipe the partition table. Then I used FDISK to make a single primary DOS partition and rebooted. FDISK still shows a single non-DOS partition. Is this because the drive only uses CHS addressing?

Also, I noticed that the drive is only recognized by jrIDE on a hard reboot. On a soft reboot (CTRL-ALT-DELETE) it stops recognizing the drive.

To the creators and contributors to the jrIDE please don't take any of this as whining or complaining. I'm having fun and this is definitely not a mission-critical task. Maybe I'm in a bit over my head. :oops:
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Re: XT-IDE on PCjr

Postby Brutman » Sat Feb 15, 2014 8:28 pm

Any drive over 8GB should be capable of LBA and will report its full human readable name on startup. What you are getting is the drive is not talking correctly to the Jr.

[1] Early in the development of the XT-IDE we figured out that using a high quality 80 conductor IDE cable (usually with the blue connectors) helped a lot of drives. It should not be necessary because we are not running at high speed but the extra grounding helps. If your drive is not reporting in correctly then make sure you have a good cable.

[2] Make sure the drive is allowed to spin up before the jrIDE BIOS tried to query it. If you have a QuickSilver cartridge that skips the RAM checking and you power on both the Jr and the drive at the same time the Jr can try to talk to the drive before it is fully spun up and ready to talk on the interface.

[3] You should never have to set a jumper on a drive to limit it to a particular size. LBA addressing takes care of that crap.

[4] Make sure the drive is jumpered correctly; it should be set to Master.


Onto your DOS 3.3 questions:

The MS site that you found had good advice. Writing zeros the MBR wipes out the partition table. That gives you a clean slate. But it doesn't just delete the one non-DOS partition - it wipes them all out. So be careful if you do not intend that behavior. (In your case you probably do want them all gone, unless you are moving this drive around to other machines.)

If the MBR truly got written FDISK should be fine and will see it as a blank drive. So I am kind of wondering if the MS procedure actually wrote to the drive. Try it again with an LED hooked up and make sure you get the blink.

If you are adventurous here are the instructions I use for wiping out the MBR:

http://www.concentric.net/~kofik/technic/dos/delmbr.htm

I don't use that page exactly but I scanned his debug instructions and they look sane. They should be nearly identical to the MS directions.


My drive *always* gets recognized after a reboot, hard or code. I'm going to take a guess that the Seagate is getting "wedged" by something it doesn't understand. During development of the BIOS I would often have that problem, but we were dealing with bad CPLD code and sub-optimal BIOS code back then.
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Re: XT-IDE on PCjr

Postby monzamess » Sun Feb 16, 2014 11:45 am

Today's update -- still no luck with hard drives (edited since first posting)

1) The first drive I tried, the WD800BB (80GB): It works fine on a Dimension 3000 P4 machine. I verified that the cables (both 80-conductor) I've tried are OK too. It's still not properly recognized by jrIDE.

2) The second drive, the ST36531A (6.5GB): Although the label on the drive says "CHS," Seagate's data sheet ( ftp://ftp.seagate.com/techsuppt/at/st36531a.txt ) says it's supposed to support LBA mode. I mounted it in my P4 PC, set the BIOS to handle it as LBA, and Windows 7 could address it. I took the opportunity to wipe the partition table. Back in the jrIDE, it still shows up as having a non-DOS partition filling the drive. The datasheet shows it has a jumper to limit capacity--jumper on or off didn't matter.

Regarding the jrIDE not recognizing the 6.5GB drive upon soft reboot: After more flailing around, I finally noticed that the only time it was NOT recognized was when rebooting after running FDISK.

My original plan was to get a DOM anyway, so if I can't use these hard drives, no big deal. I just wanted to see more success with them before I dropped more money on a DOM.
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Re: XT-IDE on PCjr

Postby monzamess » Tue Feb 25, 2014 4:18 pm

Still no luck with the traditional hard drives but I have better news.

I bought a Transcend 1GB DOM from Amazon: http://www.amazon.com/TRANSCEND-FLASH-M ... b+vertical

It's recognized by jrIDE. I formatted several partitions in DOS 3.3. It boots and works well.
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Re: XT-IDE on PCjr

Postby jmetal88 » Tue Feb 25, 2014 7:32 pm

monzamess wrote:Still no luck with the traditional hard drives but I have better news.

I bought a Transcend 1GB DOM from Amazon: http://www.amazon.com/TRANSCEND-FLASH-M ... b+vertical

It's recognized by jrIDE. I formatted several partitions in DOS 3.3. It boots and works well.



Is that the kind that plugs directly in to the IDE header? If so, it's starting to sound like your cable may be the problem with your traditional drives.
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Re: XT-IDE on PCjr

Postby Trixter » Tue Feb 25, 2014 8:54 pm

Personally, I don't see why everyone doesn't go the DOM route. It is a blast having the entire thing completely contained withing the sidecar shell.
You're all insane and trying to steal my magic bag!
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