Borderline PCjr floppy disk drives?

[hyperfrog]

Hi all,

I've been given a PCjr yesterday. It came with a color monitor and a Racore Drive 2 expansion unit, which also boosts RAM to 512KB and adds a parallel port to Junior. The computer also came with a lot of software (mostly copies) on diskettes. At first, the disk drives didn't work, but after cleaning their heads and exercising their stepping motors for a while, they both came back to life.

Although most diskettes (i.e. the ones that came with the PCjr) are now readable with either drive, I have a hard time trying to read diskettes created on other computers. I tried reading some 360K floppies that were previously given to me by an other person. Most of these cannot be read by the PCjr, although they can be read by a "modern" PC (2002) into which I installed a 5 ¼" 1.2MB disk drive. My goal is to move files from this modern PC to the PCjr. I successfully used it in the past to create system disks for a couple of old TRS-80 computers (the Model I, which uses single-density diskettes, and the Model III, which uses double-density diskettes). I know it isn't recommended to write single- or double-density diskettes using a high-density drive, but given the positive results I got with the TRS-80s, I thought it would be trivial to use that PC for adding some files to PCjr diskettes. Well, I was wrong. As soon as I add a file to a 360KB diskette, the PCjr complains about that diskette being unbootable/unreadable, although I can use it without any problem on the modern PC. For example, using the PCjr, I created a bootable DOS 2.1 diskette, then I used the modern PC to add the JRCONFIG files to that diskette, and finally I tried to boot the PCjr with that same diskette, but it didn't work (the PCjr started reading the diskette and then hanged forever). However, I can boot the modern PC using that same diskette, which means it isn't corrupt. I tried a few times with different diskettes and DOSes (2.1, 3.1, and 3.3). No success so far. All such diskettes become unbootable (when inserted in drive A:) and unreadble (when inserted in drive B:) on the PCjr only.

So my question is: Are the PCjr disk drives known to be touchy? I doubt they became uncalibrated with time (bad alignment and/or rotation speed), because they still can read the old diskettes the previous owner gave me, and both can read the same diskettes. Does anyone know how to "cure" borderline PCjr floppy disk drives?

I guess I could remove a drive from the PCjr, and then install it temporarily in my modern PC, but I'd like to avoid going through all this trouble every time I want to move a file from the modern PC to the PCjr. I guess I could also use Laplink or something equivalent to transfer files to the PCjr, but how can I run Laplink on the PCjr if I can't put it on a diskette that it will be able to read?

Thank you,

Christian

[NTEPB]

Hi Christian. Since I'm sitting here bored at work at 3:30 AM, let me see if I can help out with this...

I've also had problems reading some diskettes in my Racore-expanded PCjr at times in both drives A and B. For some oddball reason, the same disks will read in my 1.2MB drives in my 486/P1 machines perfectly. I don't believe that it's only the PCjr disk drives that have issues at times; lots of these drives in older PCs have issues, too (remember, the PCjr just turned 25 years old ). My solution...back up the files onto another blank 360KB diskette or a hard disk and format the original diskette again using the Jr's 360KB drive. The disk usually comes back to life then (for me, at least).

However, I can boot the modern PC using that same diskette, which means it isn't corrupt.

Um...well...actually, yes and no. It all depends on your definition of "corrupt". With the 1.2MB drive, it'll work fine, but with the Junior's 360KB drive, it has no clue how to read the narrower data track. Mike's page (http://www.brutman.com/PCjr/diskette_handling.html) explains the "writing to DD diskettes using a HD drive" issue perfectly. I've had nothing but problems trying to use a HD drive to write onto a DD diskette (data errors on the Junior drives, system lock-ups, etc.). Those problem disks then get met by the bulk eraser quickly.

I don't blame you for not wanting to take the disk drive out of your Junior and putting it into a more modern machine just to copy a few files over...it takes some work to do that (I know, I've done it before in desperation). If you get lucky, you might be able to find another 360KB drive locally (thrift shops) or online (Craigslist, eBay) for your modern PC. I know some of the people here use LPT ZIP100 drives to transfer data over, as well as LPT-to-SCSI adapters. A few of us use LPT ethernet adapters to network our 8088s to more modern machines to copy stuff over. I use the Xircom PE3-10BT adapter to network my Junior to my P4 machines (running WinXP) so I can create a "giant hard drive" for my Junior...saves the wear on my diskette drives.

Here's another option (with caveats)...how about INTERLNK/INTERSVR? If you have a copy of DOS 6.x or newer, you could connect your computers using a null-modem serial cable to transfer files over. The nice part is that there is a command line switch (in INTERLNK, I think) that allows you to copy the 2 main files from your server computer to your client computer using the serial cable...no need to take out your 360KB drive (this trick doesn't work with the Laplink LPT cable). After the files are installed on your Junior, then you should be able to use the LPT cable.

The problems...the computer you want to use running INTERSVR can only use drives formatted in FAT12 or FAT16 (no NTFS or FAT32). I think that INTERLNK requires DOS 3.x, also. If you want to try this method and need help, let me know. I've used this method to copy files from my dad's 486 machine to my Junior back in the day.

Hopefully all of this helps! Thanks for reading.

Jon

[Brutman]

I'm still in shock that we had two posts last night. ;-0

There are a few things that go wrong with floppy drives:

• Rotational speed: A lot of drives from the era are belt driven, and a marginal belt can slip and affect the speed of the rotation. I think the target speed is 300 RPM.
• Head alignment: don't knock the heads around, even with a Q-tip. A cleaning diskette might not do the best job cleaning the heads, but it should not knock them out of alignment.
• Track seeking: The head has to hit the right part of the media. This is controlled by the stepper motor.

To check rotational speed get a hold of an older copy of CopyIIjr from Central Point Software. There is a /T parameter that will check the speed of the drive without affecting the floppy you are using. (A test mode.) If you are off a little bit from 300 that's ok. If you are all over the map and it is a belt driven drive then the belt might need to be replaced. (The QumeTrak 142s that IBM used are belt driven. Direct drive drives are better in this regard.)

Head alignment: There is no home solution for this. You need specially recorded diskettes and an oscilloscope.

Track seeking: The stepper motors are pretty good. The best thing you can do to ensure accurate track seeking is to clean both rails thoroughly and lubricate them. I use alcohol for the cleaning part, then a teflon impregnated light oil for lubrication.

Bottom line: Clean the heads and rails well, but don't knock the heads out of alignment. Check the rotational speed and try to fix the belt if it is a problem.

Using a 1.2MB drive with the skinnier heads to write to diskettes just adds to the problems. It makes the track positioning critical. Even with perfect track positioning it is possible to misread the signal because you will have a good narrow track laid down on top of an wider track.

[Brutman]

Two part reply

Networking is a good way around this.

Jon's solution (which I still need to implement!) is ideal. Except for a boot floppy, he has no need for floppy drives.

I've been using a parallel port attached hard drive. I also have to use a boot floppy. For data transfer to other systems I use my own TCP/IP and FTP that I wrote.

The Zip drive solution is good too, but eventually you start running out of parallel ports. The problem with the Zip drive is that it requires you to power down or reboot the machine to do the actual transfer of data. (The diskette has to physically move.) The network based solutions don't require that.


Mike

[hyperfrog]

Hi folks,

Thank you for your help. I found the maintenance manual for the Qumetrak 142 disk drives. I will do my best to clean and adjust them, but my expectations are rather low.

I don't believe that it's only the PCjr disk drives that have issues at times; lots of these drives in older PCs have issues, too (remember, the PCjr just turned 25 years old ). [...] With the 1.2MB drive, it'll work fine, but with the Junior's 360KB drive, it has no clue how to read the narrower data track. [...] I've had nothing but problems trying to use a HD drive to write onto a DD diskette (data errors on the Junior drives, system lock-ups, etc.).

I know the 1.2MB drive writes tracks that are narrower. The "funny" thing is that my TRS-80 Model I, my TRS-80 Model III, and my TRS-80 Color Computer can all read disks created from scratch using a PC with this high-density drive. The TRS-80 Model I is 30 years old and uses single-sided, single-density disks (for a whopping 90KB).

I don't blame you for not wanting to take the disk drive out of your Junior and putting it into a more modern machine just to copy a few files over...it takes some work to do that (I know, I've done it before in desperation).

Well, I just did that. The damn thing is not recognized by Windows XP and also prevents the A: drive (3½") from working (no matter how I set the drive selection jumper). So I had to disable drive A: and boot from a DOS-formatted hard drive. Definitely not my idea of fun, but it worked, at last. I will try to find "new" 360KB disk drives and install one permanently in my PC (and perhaps replace the PCjr ones). The problem with eBay is that most sellers are located in the US and will ask about $25 to ship one to Canada. They also know that those drives are "rare", so they price them accordingly.

Here's another option (with caveats)...how about INTERLNK/INTERSVR? [...] I think that INTERLNK requires DOS 3.x, also.

I will try that. I thought it would require DOS 6.xx on both computers, and AFAIK, DOS 6.xx cannot be used with the PCjr.

As regards the networking solutions, let's say I'll try "simple" things first! Besides, a network adapter (or a ZIP drive or any other parallel port solution) requires a device driver, which I will need to put on a floppy disk in the first place.

By the way, Mike, please let me know when you have the DOS 5.0 patches posted.

Thanks,

Christian

[NTEPB]

Hi everyone.

Christian...

You have a good point there about the shipping (sorry...didn't realize you were in Canada). You still might want to try Craigslist. Might get lucky finding a drive there.

I completely understand your frustrations with WinXP and 360KB drives. What might be happening with trying to use your 3.5" drive at the same time is good ol' diskette changeline support, which the 360KB drive has no idea how to use, so it makes life hell. Unfortunately, with any of the solutions provided, the odds are very high that you'll have to install the 360KB drive in your modern computer again...at least temporarily.

But let's get down further to the main issue...copying files between your main PC and your Junior. My question is this...are you wanting to use some software to copy files between the 2 machines on a temporary or permanent basis?

If you want to copy files between the 2 machines every once in a while, I would look towards INTERLNK/INTERSVR or the LPT ZIP drive. Mike's solution of using the PALMZIP driver for using a ZIP drive on an 8088 machine has worked well for a number of people, even if you have to shut down machines one at a time to transfer data. For INTERLNK/INTERSVR, all you would need are DOS 3.x and the INTERLNK.EXE and INTERSVR.EXE files themselves (Google around for them...I found a few sites). The command that allows the files to copy over a null-modem serial connection is INTERSVR /RCOPY. If you'd like, I can work on some documentation on how to get INTERLNK running between an 8088 machine and WinXP (because of the NTFS/FAT32 issues with INTERLNK, we might be looking at using virtualization software (like Virtual PC or VMWare)).

If you want to copy files between the 2 machines fairly often, the Xircom ethernet adapter, in my mind, is the way to go. It takes a bit of work to set up the software (I use MS LAN Manager v2.2c using NetBEUI), as well as hardware (to copy the data onto a 360KB diskette), but it does work well for me. Yes, it requires moving the 360KB drive over to the WinXP computer again temporarily; once everything is set up and installed correctly, you shouldn't have much of a need to use a 360KB drive in your WinXP machine ever again. And no issues with NTFS or FAT12/16/32, either.

Side notes...you're right; using DOS 5.x or newer with a PCjr requires patches. Let me see if I can find them. I don't know if DOS 6.x can be patched the exact same way as DOS 5.x, but it's worth a shot. Hey, it might even let me run PC-DOS 2000 on my Junior. And yes, using the HD drives to write onto DD diskettes and having them read correctly in your TRS-80 computers still bugs me. I would have never guessed that trick would work on those systems.

(and now for a slightly off-topic moment)

Mike...

Thanks for the props. However, I did find some issues with even my own networking documentation. I found out that it still works correctly networking the Junior to my 32-bit Windows machines. Well, I've since upgraded my server to Win2K3 Enterprise x64 Edition, and it no longer supports NetBEUI , but running a 32-bit virtual machine with NetBEUI does work. I'll have to start testing various TCP/IP stacks on my 8088 machines to get it all running natively. If you ever think about writing a TCP/IP stack via TSR (similar to Trumpet) that works with MS LAN Manager, I'll be more than happy to test it for you!

Hopefully this all helps! (man, I gotta stop writing such long posts!)

Jon

[Brutman]

The patches for DOS 5 and DOS 6 can be found at http://www.brutman.com/PCjr/downloads/patch5.zip or patch6.zip.

Here is the problem. The first time the machine boots it is going to report 112KB to DOS, and not 128KB. Even if the BIOS counts expanded memory it will not report more than 112KB.

DOS 5 requires 256K or it won't run. I haven't looked in a long time, but I believe the patch copies the true size of memory from another location in BIOS to where DOS expects to find it. It then forces a reboot so that DOS loads again. DOS will see the correct amount of memory on the second pass.

You still need to use JrConfig or another device driver to load DOS above the hole created by the video memory.

I've used the DOS 5 patch before on genuine IBM PC DOS 5. I've not used the DOS 6 patch or MS DOS versions. The concept is the same - it might take some disassembly and debug to get it perfect for MS DOS.


Mike

[hyperfrog]

Hi folks,

I've made some progress, but I still have issues.

Someone gave me a nice working 360K disk drive, which I installed in my modern PC. I now have a reliable way to write to 360K diskettes. Hurray!

I also used Interlnk to establish a connection between my modern PC and my PCjr using a parallel port cable. It works, but since I'm running PC-DOS 3.1 on the PCjr, I cannot access disk drives larger than 32MB, even redirected ones. I thought: "No problem, let's use the DOS 5 and 6 patches that Mike has just uploaded". Well, I've had no success so far with those patches. I tried to patch PC-DOS 5.0 and MS-DOS 6.22 boot disks. None is working, and both exhibit the same behavior: the PCjr boots normally and displays the A> prompt (or the "Enter new date" message if there is no AUTOEXEC.BAT file), but as soon as I hit a key, Junior beeps and does nothing else. By the way, I noticed the exact same behavior when I tried to boot with unpatched DOS 5.0 and 6.22 disks and the switch on the back of the Drive Two set to the "PC" position (the Drive Two has a switch allowing the user to choose between "PC" and "PCjr" modes). It makes me wonder if I need a patch at all. In addition, the patched boot disks become unbootable on my modern PC. Is it normal?

Can someone help me with the keyboard issue? I'd really like to be able to use at least DOS 5.0.

Thanks a lot,

Christian

[NTEPB]

Christian -

I think I know what your problem is with the keyboard and DOS 5. If I remember right, I think you have to manually set the stack segment using STACKS=0,0 in CONFIG.SYS. In DOS 3.x, it figures this out for you automatically, and in DOS 5, the default setting works fine in the other 8088 machines (which should be 0,0 already). Why it doesn't in the Junior is just plain weird.

With the PC/PCjr switch in the back of the Racore...I can easily answer this question. On my system, flipping the switch to PC mode allows the computer to recognize all of the memory installed (up to 640KB) without a memory device driver, allows DOS 5 to run without patches and will start the system in 80-column mode (just like a PC). I believe the ID Byte of the computer will change from FD to FF just so programs that behave differently on a PCjr will now work just like a PC (such as the CGA game Flightmare). It will NOT allow you to use any advanced PCjr features (graphics/sound), however, and there are other small compatibility issues. Try both settings to see what works best for you (just make sure to turn off the CPU first before flipping the switch!).

In regards to the patches, I think the behavior is correct with the DOS 5 patches not booting in another computer. Like Mike said, booting with those diskettes makes DOS search remote locations in BIOS to get the actual memory count. In a standard PC, those extended BIOS locations don't exist, so those systems lock up. To answer your question, yes it's normal.

I don't know if running DOS 5 with INTERLNK will allow you to see the INTERSVR hard drives any better than DOS 3.1, but it's worth a shot. If not, I would at least try to access the INTERSVR's floppy drive to see if that even reads correctly (since that's using FAT instead of NTFS).

Hopefully this gets you up and running. And congrats on the floppy drive find!

Jon

[Brutman]

Jon has it right again. You need the 'STACKS=0,0' as the first line of CONFIG.SYS. Here is a CONFIG.SYS that should get you started:

Code: Select all

STACKS=0,0
FILES 10
BUFFERS 20
LASTDRIVE=F
DEVICE=JRCONFIG.SYS

There are options on JRCONFIG.SYS that you should explore to get the machine the way you want it. I have options set to tell it that I want 32K of video memory, an 80K RAM disk, and the key clicker turned on.

The patched DOS will not work on any other machine in the family. The memory location that is being copied on the XT is a manufacturing test area, and on a PC1 or PC2 is the amount of memory installed in cards on the bus. (It might work for PC1 or PC2.) On an AT I have no idea what is being copied, but it's not good because it locks it up every time. ;-0