Overclocking IBM PCjr, 5150 PC, 5160 XT, 5155 Portable. Introducing the Skinny Sprint! + PCjr repair
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- Опубликовано: 6 окт 2023
- Prepare to be surprised. There was a very unlikely winner in this battle!
PCB Prototype the Easy Way. Full feature custom PCB prototype service. www.pcbway.com/
I will add info here very soon on where to get the Gerbers. I have ordered v2 with relocated crystal to test.
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Tools I regularly use
DeoxIT D5 Contact Cleaner
Hanstar 861DW Rework Station
Pro'sKit SS-331 Desoldering Station
UNI-T UT61E Auto Ranging Multimeter
UNI-T UT890D Manual Ranging Multimeter
MESR-100 mk2 ESR meeter
PINECIL Soldering Iron
PinePowerPSU
TS-100 Soldering Iron
AMTECH NC-559-ASM Flux
Kester 951 Flux pen
MaAnt Grinding Pen
Multicore 60/40. 0.38mm and 0.5mm solder
TL866 II Plus Programmer
Tektronix 2246A 100 MHz four-channel analog scope
PCBs from PCBWay.com :)
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patreon.com/Epictronics
Join me on Twitter: / epictronics1
Music by Karl Casey @ White Bat Audio 
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I will add info here very soon on where to get the Gerbers. I have ordered v2 with relocated crystal to test.
Support me on patreon.com/Epictronics
Join me on Twitter: twitter.com/epictronics1
Just wanted to ask if there's word yet on where the tiny sprint gerber's could be downloaded from? Thanks!
@@BeniD82 I literally just received the V2 boards in the mail! I need to check and test them first
I had a 640k PCjr not long after they came out and installed a V20. I managed to get sooo much software running on that machine that shouldn't have. Even a serial mouse with hacked drivers.
Showed up to the channel because RUclips was non-stop recommending me the early-2000s PC rebuild/restoration. Stayed for the calm detailed explanations and hardware hacking.
I'm a computer science student and love watching people do this type of stuff because I don't have the patience to do it myself haha
I seem to have been blessed with all the patience I could ever make use of. Some of my projects have been going on for several years now. Always nice to hear that people are enjoying watching the projects
38:23 Great detective work!
The tantalum cap being a different color was also a hint.
got to say, I'm a new subscriber and I absolutely love this channel.
Thank you!
The more extreme design option would be to somehow make the board stand upright in the socket.
Thomas has already made a v2 board with the crystal and both 8284s moved. stay tuned!
I can do that.
@@VintageSupportServices : If you're going to make the board sit like that, then please sell some "helper jigs" to make soldering it easier. That sort of product would be nice for a variety of boards, including for almost anything SMD that you want to plug into a solderless breadboard.
@@absalomdraconis I don't follow? Care to elaborate on what this jig would do? Also, everything I do is free, and open source/hardware. Especially when the design was not originally mine.
So many people swear by the machined sockets, I don't really understand why. With an IC with flat pins in a round hole, that creates two slim contact points on the thin edges of each pin. Contrast that with a dual wipe socket, where the pin contact patches are on the broad sides of each pin. You get a bigger contact patch for each pin with a dual wipe socket. Plus they are much more forgiving with inserting and reinserting ICs.
That crystal mounting reminds me when I did a quick fix to a GF4 Ti 4600 back in the day... worked fine though. :)
Glad that design worked out decent. New board should be ok going forward. Plus I added that nifty logo, The boards look better with ENIG plating over the HASL.
The board works great! Too bad I missed checking the space under the FDD on the 5150. I'm running some more tests right now to figure out the optimal speed on all four machines. I will also try out some more intermittent crystals. 24MHz to 27 was quite the jump... The logo on the V2 boards looks awesome, thanks!
PCJR Side cards. :)
"Error C" on the PCJr indicates an error with the cassette interface. The BIOS uses some hard coded loops to wait during some test, my guess is that once you're past a certain CPU speed those loops aren't waiting long enough. If you were really motivated, you could probably hack the BIOS to skip the cassette interface tests, but there are a lot of similar looking delay loops in other areas you might hit next. Have a look at page A-19 of the PCjr Technical Reference, which has the source to the BIOS in this area.
Thank you, I'll do some reading
Probably also why the other PCs aren't working at higher frequencies. I seem to remember all the early IBM BIOS' had CPU timing loops which would fail if the CPU is too fast.
@@Epictronics1 To get around the boot Error C on the PCJr couldnt you just boot it with the turbo off then after booted just turn it back on?
@@gremfive4246 Oh, I didn't think to try that. I'll try it when I test the v2 boards, thanks
Thankx a lot for sharing with us. Keep up the good job! Greetings from Steven from the Netherlands
Thank you, Netherlands!
21:25 The legs are bent that way so they hold in the board while it goes through the wave soldering machine. If the legs were straight there would be no force holding the chip in and it could rise up slightly. With the bend there is some pressure holding the chip in place.
Ok, that's way better than bent legs when it comes to desoldering
@@Epictronics1Bent legs are done by hand. Those were bent and inserted with a machine. Since it's IBM most likely everything was fully automated.
Your videos like this are super facinating, I had a simular idea back in the mid 90s when I had an IBM PC XT (10MHz 8088) but I didnt have the skill nor the resources at the time, alwayse wanted to see and XT/286/386 classic PC overclocked, I later upgraded mine by swapping in an V30 and an 8087 I found in a trash picked clone.
The first PC I overclocked was a 486(DX2)-50 to a 486-80 but that was done fairly simply through jumper blocks.
BTW I noticed your P8 AT power connector isnt fully seated.
I wonder what it takes to get one of these IBMs to 10MHz. That would be really fun. I'll check P8, thanks
did similar years ago. on old 386dx with weitek 1187 co pro chips... get crystals off old video cards and over clock the board..simply swapping the crystals.. was a simple yet effective speed improvement and would show so in all speed and system indexes.. takes 5 minutes.. simple crystal swap.
yeah, I did the same thing with my Commodore 48SX25. These older machines are a bit more tricky and need an additional crystal to be overclocked
If you happen to have one, the heated bed of a 3D printer can often perform adequately as a PCB pre-heater for those pesky ground planes.
Unfortunately not, I guess I'll have to invest in a pre-heater at some point. but thanks anyways
@@Epictronics1 : If you have a hotplate that will go low enough in temperature, then that with a semi-thick piece of metal on top (preferably aluminum, since solder doesn't usually stick to it) should do a good job as a preheater (and a soldering alternative, if that ever becomes useful for some reason).
I honestly don't mind these being repair videos! 😉
You're in luck. The PCjr just broke agan :) Repair video coming up!
@@Epictronics1 Oh nice! I did happen to notice your spelling "misstake" at 40:16 😋
@@maxtornogood Haha, Oh, what a silly missstake ;)
8-bit Guy probably used a Dremel on your PCjr and returned it to Computer Reset.
Ohhhhh. I have a 5155 that's just aching for an upgrade like this, it's already got the V20. When I first discovered the PC-Sprint I think I quickly learned that it would not fit. I would love to try this out even if it means I have to solder the SMD stuff myself.
Great. I got the V2 boards now. video coming up!
@@Epictronics1I hope there will be a way for the rest of us to get a hold of them at a later date
@@cloakedalien It absolutely will. I'm thinking I should test them first. I just want to make sure my measurements are ok and they will fit
Anyone working on a version that fits the Compaq Portable better than the original PC Sprint? I made one and it blocks both the floppy drives, unfortunately. Then again I doubt I can solder the SMD parts.
Hey, have you seen Shelby's ATX power adapter for the PCjr?
Yes, It's a great project. Luckily, I got the upgraded PSU with the PCjr. I think it has enough power for a decent stack of side carts. cheers
I believe the PCjr would run faster, because its speed is effectively cut in half compared to the others. This gives you a little more leeway on chip timings.
Fast RAM is already on its way :)
Neat board design! You crammed so much into this video. Isn’t working on ild stuff fun? You think you’re going to do something kind of straightforward, but then tants and bad RAM chips get in your way. Beautiful work!
Haha, yeah, Thanks John. The PCjr and the 5150 died ten minutes after I had finished the video lol. Probably a bad RAM on the MOBO and a bad Hercules card. I ordered some new faster chips. Maybe we can overclock it even more now :)
I’d love a skinny sprint board if you have any extras.
The gerbers are going to be available very soon
you could put a socket, 7:23/57:20 were the Crystal oscillator goes to make it a short job for your other projects.? 👈👺👀👍
I tried to install the crystal in female pin headers, but it wouldn't make good contact
on the side expansion after you put the new sockets I heard two beep with black screen. does that mean one of the memory chips are bad?
I can't say for sure, but it seems that could be the case
I love your content and wish I could be a patreon supporter soon
Thank you :)
You could always mirror the originalboard design so you would have version of it that goes the other way from the socket for motherboards where it is difficult for it to fit that way.
A new version of the board is already on the way, stay tuned!
It looks like Checkit 2.1 may be assuming 80-column mode. Or is there a counterexample? Version 1 switches mode, which looks terrible on that internal CRT. 80 column wasn't all that good on a TV either, as I remember.
He needs to do the “setup” in checkit the menu and set to colour mode
idk why I find overclocking and modding and stuff on these old machine interesting, I haven't used something like this in like 20 years and even then it was outdated like mad, just gave it away lol
Awesome video as always. I really want you to try out the Deoxit D100L (100%) solution in the bottle with the metal tube. It works way better than the D5S you are using now. Also Coleco Adam would be fun to see you work on. Check out the stuff John Lundy Electronics is making for the Adam.
I had a look, it's quite pricy compared to D5S. What is the benefit? cheers
@@Epictronics1 well it works faster and better. It doesn't have any mineral oil in it as well. I only use the D5S on automotive stuff mostly now. A bottle of the D100L will last you years. I also have it in a nail polish bottle style (with brush).
"64K is NOTHING" 😢
Haha, My C64 did amazing things with what it had. Unfortunately, PCs seem a lot more RAM-hungry. 640k is pretty much the gold standard
Does the PC junior have weird physics that if you observe it, it breaks :) Great video by the way, cheers.
I think it does, It broke again five minutes after I had finished this video lol
If I remember right, the 128k ram sidecar still requires the 64k ram card to work. Have you tried the sidecar again after you fixed the ram card?
No, that was a mistake on my part. I didn't realize the sidecar needed the internal expansion card to work. I'll check, thanks
When do you live stream? I happened to catch it once. ❤
I try to premiere every week at roughly the same time. This video went live about an hour ago. You can use the bell icon and change it to "all". That makes YT send you a notification about 30 minutes before the premiere every week. cheers
@@Epictronics1 Well, that's what I just did, so I'll not be late again next week. Thanks for the interesting video! Greetings from Germany
@@e1woqf Thank you :) See you next week!
You can’t beat an intel inboard 386 in an IBM5155 especially if you swap the crystal to 40MHz and use a Cyrix 486 CxDrX2 20/40
If I could find one for a decent price, I'd grab it