IBM PCjr Part 2: Two steps forward, one step back
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- Опубликовано: 20 июл 2024
- Since posting my first IBM PCjr video, I have spent a lot of time on this machine. I've got it up and running but then run into a frustrating disk issue. I also take a look at what software there is to use on this 128k PCjr.
Links:
Part 1: • Found a cheap IBM PCjr...
Part 3: • IBM PCjr Part 3: Fixin...
Part 4: • IBM PCjr Part 4: It's ...
24 pin PicoATX supply: (not good choice for the PCjr)
www.ebay.com/itm/DC-12V-160W-...
Ebay link to 20 pin PicoATX supply: (better choice for this machine)
www.ebay.com/itm/Network-serv...
Product likn for 303 protectant:
www.amazon.com/303-30313-CSR-...
8-bit guy's PCjr restoration video:
• IBM PCjr Repair and Re... 
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The "secret password" for the diskette diagnostics (which will indeed overwrite a disk) is MPNP. I pulled that out of my memory banks as a child. Why I remember that 35 years later I don't know.
Yeah I remember asking my dad what the code was and he looked it up and for some reason I remembered that.
The B is an error. The Guide To Operations book states:
Have your IBM PCjr serviced. See "Service Information" in this section. Yeah, real helpful, I know.
This link may help, and also mentions "MPNP": ftp://ftp.oldskool.org/pub/misc/Hardware/IBM/IBM%20PCjr%20Guide%20To%20Operations.pdf
I would recommended cleaning and lubricating the drive rails, and really well. While as a kid we never experienced seek failures, every once and again my dad would open the Junior up and PM the diskette drive. I gathered he knew what he was doing since he worked as an IBM repair technician for 35 years. The drive was EXTREMELY quiet after that.
As for the intermittent ERROR H problem you're having, someone else in the comments had mentioned using a plain old ATX supply as that was the only thing that changed, and I saw your reply that you have none at the moment. I'd definitely try an ATX supply again when you get one and see if the problem goes away. If not, there's likely a circuitry problem.
One other thing of importance the Guide states is "Note: Diskette errors may be caused if your display is within 15 centimeters (6 inches) of your IBM PCjr. This problem is easily cured by moving your
display away from the IBM PCjr." In practice, I've found the Junior's monitor was pretty well shielded and was able to stay on top of the system (we always had the flip out "stand" at the bottom front open). That's why if you notice any advertising of this machine that has pictures always shows the display NOT on top of the system.
There were plenty of booter games that will work with a 128K Junior. Most of these did NOT support the 16 color modes. You will find that in cartridge games though, but those are very hard to come by. I can tell you that Alleycat, Congo Bongo, and Tapper support 3-voice sound, but are 4 colors at a time. There are also plenty of other CGA games that will likely run in that small amount of memory.
Generally, the only way to fully enjoy everything the Junior had to offer was to get the memory sidecar. Yes, it was a trying time. This was IBM's first foray into the home market, and there were going to be some mistakes along the way. Remember that in these really early days (1984 or earlier), memory, even on full-blown PCs was quite limited. The PCjr was competing with systems like the Commodore 64 and Apple II line. But you had so much more functionality with a Junior that ran DOS, that a different platform system couldn't duplicate, or even imitate well. The C64 excelled at graphics and sound, but was loading a game for 5 minutes off a floppy disk really acceptable? And imagine the horrors when a disk started wearing out or if it were exposed to stray magnetic fields, and waiting those 5 minutes to not have it work. Every system had its own share of different frustrations and especially limitations.
Over the years that followed, most people upgraded their RAM. 640KB ought to be enough for anybody. Then he made Windows. And one day, 640GB of memory STILL won't be enough. Back in these days, if you didn't have enough memory, you simply didn't have enough memory, there were no swap files or other trickery involved, it just didn't exist yet. Radio Shack Trash-80's with 4 kilobytes of RAM, really? Yeah, you had to be an EXPERT programmer to take full advantage of machines then, there wasn't much horsepower to go around. Nowadays, effectively we have a hot-rod engine in a Ford Pinto.
Even as a kid, there were a number of programs we had that simply wouldn't run on the Junior. The very few times my dad took me to work with him, I got to sit in the IBM office at somebody's PC, and run these games, usually on a souped up XT. In your case, you are much more limited; our Junior was maxed out to 640K and still couldn't run these games. With 128KB you'll have to take what you can get. If you do decide to get a memory sidecar, you'll see the capabilities of the Junior open right up.
@@jaykay18 To be fair the C64's reading of floppies could be massively sped up with the fast load carts, and the 128 with 1581 drive was faster than some DOS machines. Plus the C128 could go up to 640K RAM with 64K dedicated video RAM.
That's all fine and good, but the fast load cart was an UPGRADE, just like RAM is to a PCjr. Fast load carts basically opened the door to new possibilities with computers then. People had imaginations instead of smartphones, and a fast load cart would allow them to experience a larger set of software. In fact, it might drive their curiosity into "how does that fast cart work", or for that matter "how do I make the computer do what that game did", which could lead to them becoming programmers.
If a C128 can go up to 640K, so can a PCjr. But again, that's an upgrade. My point was the machines that were out at that time, in their stock configuration, weren't that great. With upgrades, it really opened up their possibilities.
@@jaykay18 Well yes and no. More an add-on than upgrade. And it can't of cost anywhere NEAR the amount RAM cost back then. Remember the C64 was a low costs system, and the PC Jr was an IBM machine, and IBM loved their premiums!!
But overall I kind of agree. The fast load carts only sped up what was already available, the side cart thing added RAM to make MORE stuff available!!
And yeh, you're right with thr C128. Although it was a much better machine IMO than the PC Jr.
Very true, a fast load cart was an add-on. PCjr had a speech adapter add-on, but you'd have to pay IBM prices. It also had a parallel port add-on, again you'd need to pay IBM prices for that, or find a serial printer to hook up. Fact of the matter was, IBM was THE machine to have, to be compatible with the rest of the world. They also had a tremendous software library with tons of productivity programs. Games were better on the Commodore machines, there's no contest about that. It was better suited for it. But IBM had the market share, and if you were going to get anywhere without being left with an orphaned machine, you had to pay IBM prices. There's still software even to this day that I run from the 1980s, and it runs on a modern PC, though with the "advent" of 64-bit machines today and Windows not supporting 8-bit apps, you have to use DOSBox.
LGR has a huge game collection with booters and he has a special controller to copy the disks. He can probably hook you up.
Judging from the level of frustration in this video, it should start with 'Hey smokers, Adrian Black's here'
Zankuhaaa!
Today we're gonna try installing dos on a ssd on a pcjr, luckily i have this sata to ide to sd to pcjr floppy drive adapter here.
Thank you for bringing back so many memories with your PCjr project Adrian. One of my very first encounters with computer games was while visiting a friends house with his then brand new PCjr. His was also a 128k model. The game that came with it was the original Kings Quest I and may have been bundled with the computer as it had IBM branding and came in different packaging than off the shelf games. I remember being absolutely amazed with the opening screen with King Graham standing beside the castle. In this version, there are sound effects for the birds on this screen too which I've not found on any other version. To see a game with 16 colours & 3 channel sound in 1983 or 84 was quite something. The PCjr monitor was bright, clear & crisp and LOUD just like yours. I believe it also booted straight into game just like your KQ II copy. For a time, I also had my own PCjr and the two of us would try using our wireless keyboards on a single computer. Two keyboards with one computer worked, but only one at a time. It was the first computer I ever used to connect to BBS's too. So many good memories!
I've been on a quest for a while now to try & recreate that original Kings Quest experience by finding a vintage computer to run it on. Emulation is fun but it's just not the same! To make things extra challenging, I found a RUclips video of someone playing Kings Quest I on a colour Macintosh. I thought it would be a fun project to try and find it and get it working as I was previously unaware there even was a colour version of it for the Mac! I found an original copy of it on eBay and tried it on my earliest colour Mac, an LC II. The disk tries to boot, but I believe it uses an earlier System OS than the LC II supports. This means to get it working, I'll need an even earlier colour Mac that supports System 5 or even earlier. It's a lot of hunting around to recreate a 'similar yet different' childhood memory, but I've been hooked - ever since I first saw Kings Quest booting on a PCjr!
I can relate to this post. My dad bought a pcjr in 84 with kings quest. Loved it. Bought a tandy 1000ex and just got kq1 playing tonight on it. The memories of my childhood. Awesome
Those keycaps are dye sublimated pbt, the red haloing is some sort of artifact from the process. it is quite common on IBM's keycaps, especially on the model F XT.
@@adriansdigitalbasement I believe the letters will NOT wear off with cleaning since they seem to go all the way through.
At 1:33 you're 100% correct. Those extra pins on the ATX supply can be left alone for the most part. I worked on a project that required an ATX supply and though we had a full length connector, we left the oins unused.
I remember spending countless hours playing with that keyboard diagnostic software and being entertained by that character going to the corresponding keyboard character spot when I was very young. I can't find anything further on the Internet about the utility though.
I also remember those times where various errors would appear and I'd have to turn off/on my PC/JR. Now I understand that hardware was the possible blame. When computers function I love them. When they need troubleshooting I hate them. Thanks for the journey!
Hey man. Love the detail you go into in your videos. Sometimes things aren't just magically fixed and it's good to see you documenting the process for us. Keep it up!
I just found this vid series. Brings back TONS of memories for me as this was my 1st computer as a kid. My parents took it to an authorized IBM dealer to upgrade to 256k memory. I'm just south of you in Albany area
That kings quest music brings back so many memories.
Thanks for posting this. I love the PCjr.
Me starting my ibm up secretly at night.
Ibm: BEEPBEEPBEEP
I like it how you don’t give up. Very satisfying.
In 1989, I was laid up recovering from a broken leg. A new computer arrived with King’s Quest IV - The PerIls of Rosella. I played from beginning to end. It help me pass the time I was off my feet.
Those small yellow tantalum decoupling capacitors on the disk controller card are famous for going bad and can go completely short. I'd start by replacing them first before going on to the electrolytics, and the IC's.
Radial electrolytics are very common. Did you mean axial?
Definately harder to find, but you don't need many and they are available on ebay, adding vishay or sprague to your search will help you find them.
scotty B what Scotty said !
As far as it looks in the video, those are more "pillow" shaped instead of the typical bead-shaped tantalums, which makes them look more like ceramics which should most likely be fine.
That was one of the thoughts I had as well, yet those look more like common ceramic caps. Also - though not always the case - didn't IBM love to use 3 leaded tantalum caps?
This site mentions a factory fix which seems to add some additional decoupling to the floppy controller, which might be worth a shot: www.zdnet.com/pictures/cracking-open-the-ibm-pc-jr/16/ If the voltages are otherwise stable this has a good potential of being the fix you're looking for.
On a sidenote: Don't use the 8 shit guy as a reference ... most of his projects are good examples on how to not approach problems.
Thanks for a great video. Your patience is something to model. I would have become frustrated sooner than you and gave up. I am fascinated how little the general consumer had of hardware or the manufactures ability to convey shortcomings such as the shared RAM for video and what that translated to in lack of usability in the 80s.
Hah! I loved the oddity floppy from Fred Mayer. And that is by far the best diagnostics menu, ever.
Regarding the label on your drive - I don’t recall seeing that on the ~30 PCjr’s I had at one point...
Great video!!
I really feel the excitement with the working IR modules
It's really nice that you were able to get this up and running. :D Good work! **Edit* Looks like I spoke too soon! D: I hope you're able to work out the issue with the floppy drive.
There is always the chance of a dry solder joint on the underside of the motherboard. Dry joints usually manifest themselves once everything is warmed up. Pull the motherboard and take a close look. Given that this was made by IBM dry joints probably not likely, but maybe the controller card might have been shoved about a bit, it is 35+ years old.
Great videos, looking forward to more so I subbed and hit the bell icon.
My fifth grade class had one of those things. Holy mackerel how far technology has come! 1985 was 36 years ago. 2003 is the halfway point. I was an avid PC gamer in '03. Seems like computers changed FAR more between '85 and '03, than since '03. I bet I could get right back into "Doom 3" on an '03 gaming machine, but would have no clue how to even play a game on such a dinosaur as the PC Jr.
With aging radios, I have worked on Electrolytic capacitors and the old paper caps are the first to go dipped and disk caps not so much. I even went and bought a Commodore 64 after looking at your videos and the last piece is finally coming, a 1702 Monitor next week. So My fun hasn't started yet because all units with the exception of the Monitor are untested. After seeing your series on the C64 you recovered that ants had lived in I decided ok I will see if I can get one little did I know the expense. I'm retired so I have more time to tinker than most people. Thanks for having the information on your videos.
your issue could be something to do with a capacitor.. if you think about it, it makes sense..
it only works if you leave the pc off for a while, thus giving the caps time to discharge slowly.
but then once you boot up and it reads fine, even if you reset it still works, because the machine is technically still powered, just sends reset to the cpu line, thus, caps are constantly powered during all this time..
so could be a high ESR reading from a cap somewhere..
It is probably a number of things. The monitor sitting on the machine is a possible culprit. The IR receiver or a stiff drive..
The issue you are experiencing with the Floppy Controller is identical to an issue I had with my IBM 5160, except that it was with the CGA card. I was using the composite output, and continually had problems with power cycling. The only remedy I had that worked was to replace the card. It worked fine when I let it sit for 3-5mins, but wouldn’t boot if I just cycled it. I came to the conclusion that something with the gates on the ICs must have been latching up and causing it not to boot properly.
Something you might try, if you don’t mind the mod, would be to place some high value resistors (10k or better) between the legs of a few of the caps (especially on any signals that have caps). This should help bleed those caps. If it’s a problem with the ICs starting up in an unknown state (as I suspected on my card), this could fix the problem.
There was only one kid in the neighbourhood who had a PCjr when I was growing up, and the only game I remember him having was King's Quest I. I have no idea if his machine was also 128KB or not, but I chuckled when Adrian got King's Quest II to work.
On compatibility and memories from my youth of the machine, they can be most summed up with the question: "Why does hardly any program work?!?" About the only stuff you're going to get to work on a 128K machine is stuff specifically designed for the machine. King's Quest II works because the original King's Quest was originally coded for the IBM PCjr, and then ported to other machines. With an expanded RAM machine, you're going to hit a wall with games wanting DMA for performance, and a base PCjr doesn't have DMA... My childhood machine was equipped with the bizarre Racore DMA expander which also added a second floppy drive on the top and 640K of RAM, but further complicates things since the machine was never intended to have DMA. Round 42 didn't work (which does on a stock PCjr, though might require boosted RAM), but Paratrooper did, which normally couldn't work on a PCjr. Sadly, your best bet is have this as a shelf machine and run stuff on your Tandy, as a large portion of the software that uses that video mode was intended to be used on the much longer lived Tandy line than the PCjr that was basically run one holiday season to compete against the Apple IIc.
The PC-Jr technical reference manual has the schematic for the IR receiver. If you can find a PC1373h, or rig up a functional equivalent, it wouldn't be too hard to build one. The Sidecar expansion appears to be an XT bus, but unlike the PLUS header in the Tandy 1000EX and HX, which are functionally equivalent to the XT card edge with the A and B sides swapped (a few pins are repurposed for the DMA function of the PLUS DMA/RAM card), but otherwise compatible with a simple adapter, the PC-Jr sidecar port has a COMPLETLY different pinout. It looks like all the functions are there. Should be possible to rig an adapter and run a lo-tech RAM card or something else, or build your own onto a perfboard.
Great video!
Somehow I missed watching it when it first came out... Probably because my own PCjr was in mothballs at the time and I just recently got it back out!
Sorry you are struggling with the drive controller errors so much! At one time I had about 30 PCjr’s that I rescued from a dumpster and don’t ever recall having this error! One common issue was the drives not reading disks if the monitor was too close though, but I see you had it far away in some parts of the video...
My guess is it is a race condition based on the non-standard PSU...
Just a guess: Check the reset system for the motherboard and floppy controller. The reset could be generated by a R-C delay + inverter gate or similar, so a bad cap (i.e. leaky or lowered capacitance) could cause too short reset pulses.
It would explain why the system fails sometimes but works perfectly once it has initialized correctly.
I have seen lots of equipment behave the same way with failing electrolytic capacitors. My vote is to examine further the axial electrolytic capacitors on that floppy board. Before ordering replacements, can you desolder them from the floppy board and test them out of circuit?
This is it. The "wait 5 minutes and it works" is because the capacitors discharge.
Maybe.
You're most likely correct, I actually read somewhere that someone had experienced an issue with a product they were developing where over time a static charge would accumulate and eventually would set a specific pin to high which was supposed to remain low. It's easy to forget that it's all based off of tolerances which can change over time and become unreliable with some components being more susceptible than others under certain conditions.
Jonathan Gray Someone goofed and left a CMOS digital input open. As Mr Jones says: classic rookie mistake :) Occasionally you’ll goof that way even with decades of experience. It’s easy to miss if everything works. That’s why design reviews work - even self-reviews where you go over the basics as if you were looking at someone else’s work.
Was about to suggest checking the timing and pulldown of reset signals, and I see it's been suggested quite a bit already! I've had this problem on digital synthesizers before.
17:05 - I'm guessing there's a bad electrolytic capacitor in one of the power-up circuits of one of more of the boards. These insure that certain reset signals are asserted during power-up.
I had a friend with a PCjr and we'd play KQ2 on it. Great game for the day. I didn't know then why it required so much RAM (128KB) but you taught me why here.
If you install a 2TB SSD that might fix it... No wait it needs a RTX 2080ti. :)
I agree that capacitors can be an issue with machines of this era. I would also check the mechanical connection between the card and the board. I seem to remember that those slots can get flakey as they get older. Not sure if it might be metal fatigue in the slot ... it's been a really long time since I worked on a JR. I just wouldn't rule out the motherboard just yet ... I seem to remember that there are a ton of caps on there as well. Wish I had the magic bullet for ya, but hey keep pluggin and I'll keep watchin and smilin.
On the tape on the drive, both of my PCjrs have an IBM lines logo the size and shape of the indent of your sticker. It even looks faintly like the lines of the IBM logo pushed up against it in your video. My guess is that it's a shipping cover to make sure it's nice and shiny when it gets to the end user, which seems likely given you found the label covered on your monitor if I'm remembering the right RUclipsr.
@@adriansdigitalbasement Neat.
That really is neat, for me as a car guy it's the equivalent of buying a car where grandpa never even tore the plastic off the seats from the factory. Really satisfying to think you'll be the first person to see or touch that label since it left the factory getting on for 35 years ago!
Power cycling the PCjr, the rule of thumb is to wait until you can no longer hear the fans. Basically wait 20 to 30 seconds to turn it back on.
This ^^ I can remember a PCjr demo at our computer club and the IBM rep said to wait 30 seconds after power off to reset.
The PC jr is the computer that got me hooked on PC games, when everyone else I knew at the time had Commodore 64s. My buddy's dad had a PC jr, and he'd gotten the original King's Quest 1 (the box had the silver knight on the front) for it when he bought it. We used to play that whenever I was over at my buddy's house. And eventually he got King's Quest II. I'd forgotten that they were both booter games until I saw this. I convinced my dad to get me a Tandy 1000 SX because I liked these games so much better than Commodore games.
Recap your controller card and probably the floppy too. It's a typical capacitor problem when you have to let them discharge to get it work or when it works for few minutes.
I grew up in Gresham. I had a friend in high school who had a IBM pc jr in 1989. Been shopping at Fred Myers my whole life.
That diagnostics test assortment was pretty cool. :D Not the best IR keyboard but they had to start somewhere. Well the need to expand the memory must have been like some kind of "unwritten law" of owning a PCjr. ;) All well and good to try out the graphics but you have to run the games that will run regardless, and I guess that's PC Booters.
Awesome channel! Just discovered it. ;)
The original Kings Quest will play on the PCjr. I used my Aunt's PCjr (she worked for IBM) to play it as a kid.
About the too high ATX adapter.
Depending on price, you can get an ATX extension cable.
With all the work you put into it, it seems worthwhile to get the RAM expansion. That floppy error is maddening, though. Too bad you can't try a different controller card for that floppy.
I would be replacing any electrolytic caps even if they measure correct capacitance because the esr would be way off giving you symptoms like this.
Insufficient power the floppy may need constant current. The negative 12v is invalid on a pico atx.
"It's freakin' working!" First time this got uttered :)
One possible explanation of the behaviour that the floppy controller doesn't work when the machine is rebooted, but works fine when left alone for a while is temperature: Some component might malfunction when it is warm. If you switch off the power for a while, the component cools down and the controller starts to work again.
I don't think it is a capacitor, because broken capacitors tend to behave the other way around: Warming them up restores some capacity. However, it can be any component, some TTL chip that is malfunctioning could explain it.
To test the temperature theory, you either need a possibility to cool locally, or heat locally. But as a first step, you could just try to warm up the computer before boot, with an electric fan heater or something like that. If the is temperature related, you should the error even if the computer has been off for a while.
I experienced a very simular problem some time ago. It was an ITX board and a mini-power supply much like the pico power supply. The problem was only when I used that specific power supply. The second I changed to a real ATX power supply the problem disapeared.
I suspect the issue is the floppy controller is not reliably being reset. The pulse width is too narrow for it to properly reset. Id look at the power good pin. Modern supplies generally give the PG pin only cursory support. That would be where id start looking.
In the late 1980s I worked in an university computer lab. We always waited 10 seconds after turning off the original IBM PC before turning them back on. My EE colleague said that there capacitors associated with the RAM than needed to discharge completely before the machine would reboot completely. (my background is in the social sciences, so I am just took his word for reason).
Our PCjr was pretty bad when we got it, like you found out it doesn't really work that well unless you have the largest expanded memory. The best thing we ever did was upgrade the computer and it made it so much better as a heavy door stop.
The four extra pins deliver 12V/5V/3.3V/GND
Takes me back to printing xmas cards on our tandy 1000 ex! And playing black cauldron by Sierra.
Sierra. Brings back memories. As a kid with a Tandy 1000 SL2, my Sierra games (kings quest and police quest) were not booting disks. In fact, I had to run the games from the original disk because of the copy right protection. If I remember correctly, I would go to dos, go to a:\ and type in sierra.exe to play the game. If I did this with a copied disk, it would require me to put in the original disk to continue.
been to a Fred Meyer stores in Alaska. I use to buy furniture there. I still have a table from there.
If you can get it, you should try the original release of KQ1, too .. as it was intended as "demo" for the PCjrs capabilities.
I agree with statements below, Error H cause must be a power-on reset POR type of circuit that is not working properly. A circuit that keeps the floppy controller reset until certain time has expired or known good state is measured. If it takes to long the floppy will not respond in time for the "bios" It is most likely a capacitor, but could also be a bad flip-flop somewhere. Are there schematics for the floppy controller?
If this was used at any time as a 'prop' , that may account for the sticker covers?
I agree that it's just much easier to run games on a tandy. I've got a pcjr setup for use in my collection but I always go for my tandy 1000 TL/2 instead.
Great video Adrian, thank you! BTW: did you try using DOSBox on your current machine? ;-)
Having the monitor on top of the case can cause interference. We had a metal stand which kept the monitor away from the computer. Not sure if it was related to your issue here, but in case it helps someone fix their issue.
I miss owning one of these. Had one, I think it had 640K of RAM or something.. But I also had the 20MB external hard drive.
I don't know if someone knows about the floppy disk error, but I would assume that some logic IC related to the disk is not working properly. I would blame the floppy disk controller in that card. But since you don't have any other card connected, it might also be an issue with the main board. Anyway, you should check for some CF/SD cards adapters for this machine (if they exists, which I think they do).
If IC has gone bad it will not work sometimes and then sometimes not. But instead, the IC may not be able to work properly if there is one or more capacitor(s) gone bad as then the IC lacks the proper voltages and current. As capacitors are semiconductors they can work pretty unpredictable and unstable when they are bad. Eventually they can even explode.
I vaguely recall the small amount of memory on the PCjr to be one of the most common complaints about it. You really needed a memory expansion module in order to do anything useful. Combined with its other problems, most people just decided to get another type of computer entirely.
The error might be why the IR board was removed?
@@adriansdigitalbasement In your video testing, when did the error appear? Check the video and see what item has been added or changed prior to the error. I suspect the power source, as in the video I don't see it prior to that.
@Adrian Black .. I don't remember this floppy drive error.. in your previous video... ... ... It behaves the same when you use the normal PC power source???.... instead of this adapter for the adapter of the adapter that adapts to the adapter??? 8-}
NO SERIOUSLY my best guess... that adapteer (the blue one in 14:31) is liking some residual energy into the motherboard .. keeping some corrupt info that causes the floppy to fail at next startup ...
PCjr specific games to find: Jumpman, Touchdown Football, the cartridge games like Mouser and Crossfire.
thought the football game was cool, when i heard it speak.
I'd love for someone who bought the Tandy sound mod kit from PC Enterprises to do a video on what it involves. The Tandy video mod information was always widely available, even on IBM Canada's website. Most Tandy 1000 games allowed selecting video and audio separately so they could be used on a PCjr with just the video mod. But I did have one game that required both Tandy video and sound. Since it couldn't detect the Tandy sound on my PCjr I had to run it in crappy 4 color CGA. IIRC it was some Hoyle's card game and it used the rarely used yellow brown green black option instead of the white cyana magenta black pallet 99.999% of CGA games used.
Anyway, after paying for one Tandy video mod kit from PC Enterprises (one common 7400 series TTL kit, a bit of wire, and an instruction sheet on traces to cut and what to solder where) I never bought another. I salvaged the chip from various old or dead boards for a few other PCjrs. I figured their Tandy sound mod had to be something equally simple and I didn't want to pay a ridiculous price for a couple bucks worth of parts.
Sorry you got frustrated with this one Adrian. I did find it interesting though! I think the problem is with your floppy controller card. The problem looks temperature related as the issue presents after being turned on. You probably have a bad solder joint caused by expansion and contraction due to the cycles of heating and cooling. I would go over each chip with fresh solder. Failing that you have a bad chip somewhere.
Not even knowing what it was for sure, I bought a PC jr at an estate sale without the monitor + 2 model M keyboards for a total of $15. It was in 2 banker boxes with other items. Which included a bunch of sidecars. 2 512k expansions, printer, and I can't remember the other right now. There's also 2 external 5 1/4 drives and a joystick. And all the original manuals and dos disks. But I picked up a monitor and another joystick off ebay, so I have a full blown 640k PC jr
The Microsoft and IBM versions of the 128K sidecar are hackable. The IBM one has a simple jumper to add when you replace the 4164 RAMs with 41256 RAMs. This allows you to change the sidecar to 512K to get a total of 640K on the Jr. The only downside is you need a TSR on a floppy to load with DOS to use the extra memory.
Instead of ordering a new power supply, just use an extension cable and mount the power supply to the wall using some *strong* double sided tape.
I got a PCjr for free back in the early 90s and it came with The Black Cauldron and it ran.
It was a boot disk.
Fred Meyer bought his first store in the 1930s. Was really big in the 1970s and 1980s, so I am not surprised you found a Fred Meyer floppy
First computer I ever used in school. I remember having to insert a BASIC cartridge in the left slot and playing some math games.
That 24 pin pico PSU would be good for a little bench top PSU
The floppy controller error could be caused by the psu. It could have not enough amps. Try a psu with 6 amps.
I would delve into the events at CPU level that occur with the error, so try to capture using a logic analyser what happens when the disk is accessed until an err
or occurs. I agree that j UST replacing the original electronics defeats the idea of owning retro kit unless it's the last resort to save scrapping the unused case. A systematic check of all cables, solder joints and connectors would also be useful. Is one area of I/o or memory associated with the operations that trigger an error?
Freddies doesn't sell floppies anymore hardly even have CD-R/Ws and DVD-RWs and I remember putting the clearance stickers on the last PC RAM, BD-Rs and Video card we sold at the location I worked at.
I actually have a boxed copy of the booter version of King's Quest 2 in my collection. Didn't know it was rare.
I have one of these computers 128KB New in the original box with original packing with Keyboard also in original packing. I've been told to hang on to this machine since it's somewhat rare nowadays in the original box styrofoam and all. I don't have any way to try it since I don't have any cables for it
They make ATX power extension cables. It would give you more flexibility in placement.
Wonder if the keyboard cable had an adapter that extend to the back and was lost with the original power supply
thanks for the video!
Could be sequence of power rails turning on. Which could come up first, 5v or 12v etc?
Note: all this presumes you want to keep tinkering with the PCjr. That said, I would definitely get into some diagnostics on the controller, checking ICs, and so on. Next on the list, assuming you can overcome the disk issue, (and I'm asking the question broadly, for some folks who might be PCjr enthusiasts), is anyone making larger internal RAM expansion boards? That could be a route to go. 384 or 512k...
@@adriansdigitalbasement I feel ya, man. I see one (at a glance) on eBay but it's $36.
w/o the 'twist' in the floppy cable, is the fdd set to ds0, or still set to ds1 ? maybe replace the 5.25" fdd w/ a 720mb 3.5" fdd ? not oe, but perhaps a bit more real world useful. pls take care & stay safe.
Awesome 😎
Your error sounds like a bad cap, high esr and low capasitance. Try hesting the board with a heat gun in different sections to see if it chances the behaviour, either make the problem constant or make it o away until it cools down.
It had its own versions of some games, I had some Sierra stuff, LSL of course but Kq5 worked on it but it said of jr on the label
I mean 2 lol
A case where the Tandy 1000 owner could look down their nose at the poor sob that bought an IBM PCjr because it had an IBM brand label
Can you imagine the horror of buying the Jr because it's got enhanced graphics and sound - presumably for enabling home computing game play - and then you find that is very problematic to find games that can run on it at all, or run reasonably enough to be playable. Just compounds the misery around what was one of the most disastrous computer models of the 80s (the Apple 128K Macintosh a very close runner up).
I've still got a bunch of floppy disk games - originals and copies from the early 1980's. Spacewar, J-Bird, Sopwith, and Digger are 4 that come to mind that could work on a PC Jr. Can do some research and get you a list of games that will work if you like.
Tanner Electronics in Carrollton TX is selling new-in-box PCJr keyboards for $12. The two I have feel great. No signs of degredation.
TI/99/4A best childhood computer
Why not just get a motherboard cable extender? Also for the Drive, have you cleaned the heads with alcohol and a q-tip. You may also need to grease the drive mech that move the heads. Its the long rod the head moves up and down. This can get dust and dirt on it so clean and grease that too. Then look up the cap issue?
Hopefully I'll have better luck with my PCjr. I don't even have a 5.25" DOS disk, so I'm stuck with BASIC right now.
Error H might be a power supply problem. Too much power or not enough causing a brownout condition on the CPU. I would put a LM7815 on the power rail to lock it to 15V and clean up the power supply.
Love fred meyer! I live in Beaverton, freddy's is one of my go tos