New JR user.. Monitor, disk, DOS questions..

Hardware questions and modifications

New JR user.. Monitor, disk, DOS questions..

Postby Sharkey1331 » Fri Mar 06, 2015 9:34 pm

Hi guys,

I'm starting to get set up with my PC Jr. I don't yet have a monitor for it, and I've got a couple of old looking boot discs that I've not yet tried.

Is the official CRT monitor the best way to enjoy this beast? I'm guessing that, composite to TV will result in 40-columns only? I searched around here, and did not see any proof that anyone had yet gotten their PC Jr. to connect to a modern LCD VGA monitor.. I think I'd rather try to find the CRT monitor and use that than get a VGA sidecar, mod the motherboard, etc. Thoughts? Anyone got a PC jr. monitor for sale?

Part II- getting a set of discs.. I think I'll need at the least a DOS disc to boot from. I've not powered up yet (waiting for a power supply to come in), but I do have a boot disc.. Looks old, and clearly the disc sat in the same position for a LONG time- the disc rotates in its floppy jacket, but where the media sat under the read/write window, it is discolored. I'm thinking I probably do not even want to try this disc as it might hose the drive? Where can you even buy these discs anymore, and also is there some sort of newbie boot disc mailing program here? :-) I think if I could get a bootable floppy with software on it that would allow download via Xircom eithernet adapter, I'd be self sufficient from there.

Can't think of anything else just yet- but if you guys know of some other "highly suggested" items for newbies, I'm all ears!
Jason
IBM PC Jr. NEWB! Parallel sidecar, Hotshot II (soon to be replaced with JRide)

Also, check out my clone of the Altair 8800micro Clone:
https://www.youtube.com/watch?v=y19zdzP ... yX5JoOO4qA
Sharkey1331
 
Posts: 28
Joined: Fri Mar 06, 2015 8:19 pm
Location: Odenton, MD

Re: New JR user.. Monitor, disk, DOS questions..

Postby MikeModified » Fri Mar 06, 2015 10:15 pm

I don't have a spare monitor, but I do have an original monitor box & Styrofoam (used to ship a monitor to me) that I'd be willing to send to someone with a monitor for you.

OBTW, welcome!

Mike
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Re: New JR user.. Monitor, disk, DOS questions..

Postby Brutman » Sat Mar 07, 2015 8:57 am

You can use the composite output on the Jr and get 80 column text. The Jr does not really know or care which of the three outputs that you are using, but there definitely is a signal quality difference.

- The TTL/RGBI output is the best. A CGA compatible monitor is required for this. The machine is designed for the PCjr monitor, which has a speaker onboard, but the PCjr monitor has a pretty coarse dot pitch so it is not going to be pleasant at some color combinations. (Which is why people did the thin-font modification.)

- The composite output is second best. I used this for years with an Amdek amber display. Great for text and usable at 80 columns if you don't mind 16 shades of amber. (Well, not so great with some color combinations.) A color display running off of this is usable in a pinch, but not great for 80 column text.

- The TV output is the worst. Avoid it for regular use.

-----

Floppy drive heads can be cleaned, and you'll probably need to lubricate the rails and clean the heads periodically. If the diskette is falling apart or questionable then I agree, don't use it.

I just recently mailed diskettes to Corey. I don't mind doing this, I just have a very high latency time between requests and mailing. 8-)

You really want to get a mothership or "tweener" system that you can use to help maintain the older systems. I have a few different computers for this but the general idea is that they have a mix of floppy drives and other storage in them so that you can make boot diskettes and do data transfers. Once you get a complete set of boot diskettes and networking the need goes down quite a bit. Virtual machines on modern machines also can be used for some maintenance tasks.

----

What region are you in? I have genuine PCjr monitors and I'd like to thin out some of the stockpile; it won't be free the price will be right. The bigger problem is shipping; I've shipped two or three over the years and have not had any problems, but i usually pack them like they are going to the moon so that they are well protected. Another option is to wait for somebody who is trying to unload a system in your area; that happens from time to time and I post a message in the for sale section when it does. (As do others ...)
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Re: New JR user.. Monitor, disk, DOS questions..

Postby Sharkey1331 » Sat Mar 07, 2015 12:41 pm

Awesome, it sounds like composite will work until I am able to get something better. I'm in Odenton, MD (near Annapolis).. Not sure if that is close to you and/or some monitors.. :-)

Today I pulled a 486 out of the garage- I've had this machine since college days.. From recent eBay madness, I have a "parts" PC Jr. (no power supply, lots of hacks on the floppy card, missing drive ribbon cable, case is dodgey.. It was cheap though! I pulled the floppy drive out of that, and was stunned to see that my 486 was able to drive it with just the cables/guts that was already in it, once I adjusted the BIOS.. The one disc it came with apparently has DOS 3.20. After cleaning mildew off the disc magnetic surface with soap & water and q-tips, and later with alcohol, I actually got the computer to boot from the floppy. BUT, that is it- that is all it will do. It can't show me the directory. Interesting that it would boot?! I wonder if a system disc always has the OS at a known spot, and the BIOS boots it, but perhaps the FAT is hosed, therefore no directory? That is my theory. The disc did have some light groves in a couple spots- didn't look terrible.. Anyone got a guide for how to clean the head/rails? Would this help?

So, long story short, I now have a "mothership" machine (I think).. It has a working DOS 6.22 on its HD, and a CDROM that works- so I can get software on to it, and possible copy SW onto 5.25 discs as long as the drive is good and its because the disc is hosed that I can see the directory... I also just got my Xircom interface in the mail, so ultimately I'll be able to pull SW directly to either mothership computer, or PC jr., once I am able to put telnet/ftp software on the computer.. Chicken and egg dilemma! Guess no where local would sell 5.25 discs... Gotta ebay I'm guessing?

Jason
IBM PC Jr. NEWB! Parallel sidecar, Hotshot II (soon to be replaced with JRide)

Also, check out my clone of the Altair 8800micro Clone:
https://www.youtube.com/watch?v=y19zdzP ... yX5JoOO4qA
Sharkey1331
 
Posts: 28
Joined: Fri Mar 06, 2015 8:19 pm
Location: Odenton, MD

Re: New JR user.. Monitor, disk, DOS questions..

Postby Brutman » Sat Mar 07, 2015 1:12 pm

East coast... I'm west coast. Wait for a closer monitor. The longer something is in transit, the more chances it has to get damaged.

Cleaning the drive: http://brutman.com/PCjr/Eugene_Club_Doc ... eaning.pdf

The general idea is to clean any accumulated gunk from the rails, and then to lightly lubricate them. I clean the rails using a Q-tip with some isopropyl alcohol on them. You want to move the head carriage back and forth to make sure that you clean all of the places where it slides, and any accumulated gunk where it stops.

After that, lubricate with a very light machine oil. Radio Shack might still be selling a tube of oil that has Teflon in it, and that stuff works great. Sewing machine oil applied with a Q-tip also works. Do not spray anything in there. And never use WD-40; it is not a lubricant.

Cleaning the heads is best done with a dedicated cleaning diskette. If you are very careful you can gently lift the upper head assembly slightly to gain access to both heads, and then clean with a Q-tip. Isopropyl alcohol works there too, but be sure to get the 90% + pure stuff, not the normal 70% version that people use for cosmetics. You need to wipe the heads left to right or right to left and you need to be very careful:

  • Tearing a head off kills the drive
  • Knocking a head out of alignment kills the drive
  • Leaving cotton fibers on the head is a bad thing too.
  • Lifting the assembly too far and bending it out of shape is also a bad thing to do
In short, there is a fair bit of risk in doing this, so don't just rush in in a hurry.

You need to get some blank diskettes. eBay is the preferred place for that, or fellow collectors. Check out the forums at vintage-computer.com and post an "Item wanted" there; one or two people will reply. The pricing and terms are buyer-beware of course.
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UPDATE: Working Drive! RE:New JR user.. Monitor, disk...

Postby Sharkey1331 » Sat Mar 07, 2015 3:29 pm

Well, I'm not sure what I did, but the drive is now working.

I took the non-working 5.25 drive out of the 486 "mothership" computer (which will be used to transfer files needed to get the PC Jr online).. I cleaned the rails using Q-tips and rubbing alcohol. They were indeed funky, and after cleaning, moving back and forth to get all the spots, more cleaning, and then application (again using Q-tips) of silicon with teflon lube, I then gently cleaned the heads with a wee bit of alcohol on a clean Q-tip. I put the drive back in place, and rebooted the machine. It would again boot to DOS 3.20 (seemed quieter I might add!) but still no dir or any other functions once it booted.. It seemed it could not read the disc...

Well, you know you're desperate when you decide to randomly try different jumper settings and fool around with the BIOS! (To be fair, I did "google it", and came up with nothing for the jumpers on the back of the floppy drive.) For anyone that might be here that is only messing with these old computers because it is retro and edgy, but they were born with much newer machines being their first (Say, first computer was maybe a Pentium III, or some random XP box) this will seem absurd, but back in the day, there used to be some undefined amount of time needed to be spent when building a PC, where you'd just have to F$#@ with it to get it to work. Long before plug and play, there were jumpers, and besides, who reads the manuals anyways? Anyone with me on this? You'd basically try stuff (somewhat cautiously and slightly educated guesses of course!) until it worked?

Anyways, long story short, moving the jumper on the back of the drive one spot over from its original position, and then moving it to drive "B" in the BIOS somehow allowed it to work. Of course, I can no longer boot to this disc... However, now the machine boots (from HD, which is DOS 6.22) and then B is able to be accessed fully. I can see the directory, copy files off, etc. Not sure how or why, but its pointless to question now :-)
IBM PC Jr. NEWB! Parallel sidecar, Hotshot II (soon to be replaced with JRide)

Also, check out my clone of the Altair 8800micro Clone:
https://www.youtube.com/watch?v=y19zdzP ... yX5JoOO4qA
Sharkey1331
 
Posts: 28
Joined: Fri Mar 06, 2015 8:19 pm
Location: Odenton, MD

Re: New JR user.. Monitor, disk, DOS questions..

Postby Brutman » Sat Mar 07, 2015 3:41 pm

You might want to do some reading on floppy drive cables - twist vs. non-twist.

The jumpers you were messing with are probably the drive select jumpers. I forget the entire story, but before IBM you would set a jumper on a drive to tell the drive which drive it was on the floppy controller chain. IBM thought this was too hard, and for their two drive systems they shipped both drives jumpered the same, but they put a twist in the cable after the first drive to make the second drive look like the second drive on the cable even if it was cabled as the first drive. Thus the drives become swappable without any jumper changes ...

You've undoubtedly hit this, which is why you magically have a B drive now. What does your cable look like, and what is plugged into it (and where) ?
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Re: New JR user.. Monitor, disk, DOS questions..

Postby Sharkey1331 » Sat Mar 07, 2015 6:02 pm

You were correct- the magic B drive config was using the cable that had a twist in it.. The box originally had an A drive (3.5", I think it's 720 kb flavor), and the cable (is this IDE?) was connected to that. Daisy chained off the same cable is the connector I used, with the twisty part in it. When I was originally trying to get the 5.25 to work, I simply plugged it in as I mentioned, and left the 3.5 connected and powered. Setting things in the BIOS, I noticed both drives going at the same time- so I unplugged power to the 3.5 early on. I'm guessing that, with the jumper moved in magic B config for 5.25, the A drive would have worked with the 3.5.. I don't have any discs for that drive either, so I just left it unplugged.

I moved the non-twisty connector to the 5.25, moved the jumper back to original (think this is position 0) and moved the 5.25 to A in the BIOS. No worky however.. I had to go back and move the jumper to the next position over as it was for magic B.. Now it is functional as A drive, and I can boot the computer this way. Interestingly, when it boots to DOS 3.20, it knows nothing about C drive, even though the BIOS is still configured for it. I don't know the history of DOS so well yet- is this because 3.20 wasn't a time when people had C:\ drives? I'm thinking this unlikely as the original IBM PC which predated the JR had a 10MB MFM in it (I think?)

I can still get my machine to boot from the HD by just opening the drive door on the 5.25 and booting. Then it comes up on the HD DOS version 6.22, but knows about the A: drive and also the D: CDROM drive, so I have a way to easily get files to the A: floppy from another, internet enabled modern PC. I might try to figure out more to the puzzle- it would be cool to have this 486 machine able to boot from floppy (DOS 3.20) and have at least the hard drive. I'm thinking the CDROM might be over the top with that old of a version of DOS. Also, I need to try to get the Xircom network interface going too. Forgot how fun these old machines were!!!

Jason
IBM PC Jr. NEWB! Parallel sidecar, Hotshot II (soon to be replaced with JRide)

Also, check out my clone of the Altair 8800micro Clone:
https://www.youtube.com/watch?v=y19zdzP ... yX5JoOO4qA
Sharkey1331
 
Posts: 28
Joined: Fri Mar 06, 2015 8:19 pm
Location: Odenton, MD

Re: New JR user.. Monitor, disk, DOS questions..

Postby MikeModified » Sat Mar 07, 2015 7:14 pm

Sharkey1331 wrote: I'm in Odenton, MD (near Annapolis).. Jason


I lived in Herald Harbor (in the woods at the end of Cherry Trail) when I had my first jr (bought new).

Mike
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Re: New JR user.. Monitor, disk, DOS questions..

Postby Sharkey1331 » Sat Mar 07, 2015 8:30 pm

Small world, eh? You still in the area? If not, you'd not recognize Odenton any more, its really been expanding..
IBM PC Jr. NEWB! Parallel sidecar, Hotshot II (soon to be replaced with JRide)

Also, check out my clone of the Altair 8800micro Clone:
https://www.youtube.com/watch?v=y19zdzP ... yX5JoOO4qA
Sharkey1331
 
Posts: 28
Joined: Fri Mar 06, 2015 8:19 pm
Location: Odenton, MD

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