We made some unbelievable discoveries about this Plexus P/20!

Рет қаралды 87,263

Күн бұрын

We are back with the broken Plexus P/20. In this video I talk about some amazing discoveries we've made on this machine which gives me the right information and the tools I need to attempt to repair it.
Part 1: • What is this rare mult...
Part 2: • First power up of the ...
Part 3: • Booting UNIX on the Pl...
Part 4: This part
00:00 - Plexus Recap
01:23 - Intro
01:40 - Fixing the Reset Fault
10:22 - WTF is Error 4F02?
16:42 - Enter Usagi Electric's Community
18:55 - A Literal Pot of Gold
25:44 - Back to the Community
27:04 - Error 4F02 - No Ram Detected
28:02 - 68000 Memory Management
32:58 - Looking for a Mapper Signal
36:01 - A Huge Smoking Gun
38:36 - Troubleshooting Memory Again
45:06 - Replacing the Flip-Flop (Chip U4F)
50:45 - This is Freakin' Good
53:05 - Trying to Boot Into UNIX
55:17 - What's Next
-- Links
Plexus P/20 Discord channel at Usagi Electric:
/ discord (Plexus channel)
General Adrian's Digital Basement channel:
/ discord
My Github Repo (with ROM dumps and images)
github.com/misterblack1/plexu...
Plexus P/20 Brochure:
www.bitsavers.org/pdf/plexus/b...
Plexus Unix:
www.bitsavers.org/pdf/plexus/b...
MFM emulator:
www.pdp8online.com/mfm/mfm_ol...
Fujitsu Hard Drive Brochure:
archive.org/details/bitsavers...
Omti 5200 Manual:
oldcomputers.dyndns.org/publi...
Adrian's Digital Basement Merch store:
my-store-c82bd2-2.creator-spr...
Adrian's Digital Basement ][ (Second Channel)
/ @adriansdigitalbasement2
Support the channel on Patreon:
/ adriansdigitalbasement
My GitHub repository:
github.com/misterblack1?tab=r...
-- Tools
Deoxit D5:
amzn.to/2VvOKy1
store.caig.com/s.nl/it.A/id.16...
O-Ring Pick Set: (I use these to lift chips off boards)
amzn.to/3a9x54J
Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
amzn.to/2ye6xC0
Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
amzn.to/3adRbuy
TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
amzn.to/2wG4tlP
www.aliexpress.com/item/33000...
TS100 Soldering Iron:
amzn.to/2K36dJ5
www.ebay.com/itm/TS100-65W-MI...
EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
amzn.to/2RDSDQw
www.ebay.com/itm/USB-Logic-DS...
Magnetic Screw Holder:
amzn.to/3b8LOhG
www.harborfreight.com/4-inch-...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
www.ebay.com/itm/14-16-18-20-...
RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
www.ebay.com/itm/1-2-5-10PCS-...
Heat Sinks:
www.aliexpress.com/item/32537...
Little squeezy bottles: (available elsewhere too)
amzn.to/3b8LOOI
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino

Пікірлер: 570

@xxHANNONxx 4 күн бұрын

Whoever thought some old Plexus nobody ever heard of was going to be peak youtube? This is the best series ever!

@Dukefazon 11 күн бұрын

It's crazy that there's virtually zero information on these machines, a very few of them exists still today and the one you got happened to have a LOT of vital information kept on an invisible to the naked eye part of the hard drive. Mindblowing discovery!

@thenerd6192 4 күн бұрын

I wonder if the hard drive was imaged at the factory, and it was the engineer making the base image who made the typo and put the /user partition at the wrong address, meaning every computer would ship with 90% of the technical documentation in unallocated space. That seems like less of a coincidence than “this one machine happened to have been used by one of the engineers and then got repurposed for general business use”

@TechTimeTraveller 4 күн бұрын

That was very lucky indeed! There are tons of small companies that came and went back then and were only known by the customers who used them. The big companies get all the press but often the most interesting stories come from the smaller ones who had to survive on wits and luck.

@root42 4 күн бұрын

Similar thing happened to Sierra. Source of the AGI interpreter source on the game discs!

@danielmantione 4 күн бұрын

This is a general problem. The 80s were about much more than home computers. A lot of interresting business computers (mainframes!) were made, however, as there was no standard computer architecture yet, there systems had small user bases. Unlike home computers that were carefully stored at attics for decades, the business computers were destroyed after their economic life did end. Companies that made them went out of business. Therefore, we kind of know everything about the home computer side of the 80s, but the business computing part of the 80s is basically one huge black page, with very little hardware and documentation that did survive.

@Dukefazon 4 күн бұрын

@@root42 Or they happened to have Al Lowe, who still has the source code for a lot of Leisure Suit Larry games :)

@rommix0 4 күн бұрын

I love these types of vids. Don't you just love it when a community comes together to get a rare beast working again. From the unix community to the N64 decompilation community, it's incredible.

@johnpetruna8888 11 күн бұрын

"I'm now in contact with that person!!" 23:15 (This reminds me of when the teenager in "WarGames" tracks down and meets the designer of the WOPR, and together they save...the world!)

@slightlyevolved 4 күн бұрын

Adrian meets the designer of the Plexus and together they save the HARIBOS!

@asanjuas 4 күн бұрын

One good thing is one video on the channel with this person.

@xlr8r171 4 күн бұрын

@@slightlyevolvedNo Haribo is safe!

@andycheese9476 4 күн бұрын

WOPR/Joshua : Shall we play a game?

@TortureBot 4 күн бұрын

It's so funny you're talking about War Games because I just saw that on a special that Andrew McCarthy did on the Brat Pack and all the movies they were in during the 80s. Loved that movie along with Cloak & Dagger, Tron, etc.

@Dorelaxen 3 күн бұрын

Hey Adrian! Met you at VCF this weekend (I was the guy with the "cool shirt")! Thanks for taking the time to chat and get a picture with you!

@Evergreen64 4 күн бұрын

For all the fake news and flame wars that the internet has become, THIS kind of thing is what the internet was made for! I love seeing things like this. Because people can be connected to other people with just the right set of skills to help solve a problem! Good on everyone who contributed to this!

@XPbIM3 4 күн бұрын

-we need a circuitry to pull off a reset signal -lets use the whole 16mhz atmega board to do that! -great idea! Just finished watching: what a roller coaster! Absolutely amazing!

@horusfalcon 4 күн бұрын

Hey, when you have a bushel basket full of the things, it only makes sense to use them for everything under the sun.

@kaitlyn__L 4 күн бұрын

I thought it was kinda overkill at first too, though I must admit being able to turn a reset loop on and off with the startup key is pretty handy!

@sparcnut 4 күн бұрын

Yeah, and that atmega might even be somewhat on par with the 68010s' performance....!

@paulstubbs7678 4 күн бұрын

Sounds kind of crazy, like bolting an original PC to the latest and greatest computer just to drive it's reset line!

@petersage5157 4 күн бұрын

He did mention that he intends to replace it with an attiny.

@SaltyMeatHook 4 күн бұрын

Still watching, halfway through. But holy moley!!!! The partition was still there! You are in touch with the person who worked on that machine! The machine was used at PLEXUS!!! Un-freaking believable!

@argvminusone 8 сағат бұрын

There has been much talk about everything wrong with the Internet these days, but it has certainly succeeded in connecting people.

@Dirty_Bits 11 күн бұрын

The folks in the Usagi discord are a brilliant bunch. So happy to see you collaborating with them. This has been a very exciting and interesting series. Can't wait for the next one!

@chrisjones8741 4 күн бұрын

I’m getting “invalid or expired” on the discord link in the description 🙁

@Dirty_Bits 4 күн бұрын

Try joining from an Usagi video. He puts a fresh link in every vid.

@rachelaudrey6241 4 күн бұрын

Some incredibly smart people, but also some incredibly loud, obnoxious, arrogant ones, as well. :( Can't stand it there.

@thecorruptedbit5585 4 күн бұрын

I was reading the wikipedia page about the 68010 the other day, and I saw that someone added the Plexus P20 as a machine that used the CPU, a few days after your first video came out

@paul_boddie 15 сағат бұрын

Well, now we know that they watch Adrian's videos! Although the 68010 didn't ship in the volumes that the other products in that family did, it was hardly a niche product given the top-tier vendors (AT&T, Sun, Apollo, HP) who used it in their products.

@selske23 4 күн бұрын

I worked on forklifts for a while as an electrician, some of the older machines had so many botched quick "fixes" that opening up the cover and looking at the the wires made you feel depressed, but with schematics in hand I always felt convinced I could find and repair any issue properly. Technical documents are such a big help, especially on complex parts

@Virnik 4 күн бұрын

Am I weird just because I find these kind of investigations entertaining, interesting, and actually something to learn from? I grew up in times when these kind of computers were being retired, and new kind of intel-based cpu archs being introduced. I do recall old Motorola CPUs, just not as its primary user, rather than someone who found one on somebody else's attic, and made it work out of shere luck and dumb/blunt will. I am not electrician engineer like Adrian, but I do understand the theory, which makes it easy to 'consume' his content. I do love Adrian's channel. I am computer enthusiast and Unix/Linux Engineer (by job). But these old computers are really something which raises curiosity and interest. Big thanks to Adrian for his streams.

@xxHANNONxx 4 күн бұрын

OMG, I hope the person from Plexus comes onto show, and has a chat about it's development!

@Jody_VE5SAR 11 күн бұрын

This is a tour-de-force in crowd-sourced troubleshooting. Adrian - this will become a landmark reference in how to leverage modern tech to keep old tech alive!

@donmoore7785 4 күн бұрын

What you found on the hard drive is truly amazing, as well as the fact you are in contact with the former user of the machine.

@necro_ware 4 күн бұрын

Wow! Who needs Hollywood if we have such thrillers in Adrian's basement? Very cool! 0_o

@femboichik 4 күн бұрын

The Retro computing community working at their best! So awesome, Adrian!

@RoyEltham 11 күн бұрын

What a stroke of luck to find all those technical docs and whatnot for the machine on it's hard drive. Freakin' amazing! :D This series has been fantastic to follow, thanks man!

@BaRtJuHh083 4 күн бұрын

Its so nice to see the internet being used for good things and all the people jumping in to help you instead of being used for scams, commercials bullying extortion and all the other crappy things...it cool to hear all those people joining in to help you figure it out and together being able to probably fix this thing...keep up the great content and hope to see the next p/20 video👍🏻😁

@granitepenguin 11 күн бұрын

This is the kind of series that restores faith in humanity coming together for a common goal. The only thing missing is a Sally Struthers commercial asking for donations.

@b33zNet 11 күн бұрын

Lol you said it and I laughed at it... we're old lol

@Virnik 4 күн бұрын

@@b33zNet sad fact. as long as you can make a new step, you're good. Being 'old' is just a title. What you'll do with it matters. The title itself doesn't.

@horusfalcon 4 күн бұрын

@@b33zNet "You wanna make more clock cycles.... sure, we all do!" 😁

@argvminusone 8 сағат бұрын

This sort of thing gives me hope. If we somehow do create a Star Trek post-scarcity society where no one has to work, people won't all just sit and watch TV all day. They'll find something interesting to do. The drive to discover and accomplish will still be there.

@packetman 2 күн бұрын

This kind of stuff restores my faith in humanity. When the computers take over the world, they will remember these people in a good way.

@anotheruser9876 4 күн бұрын

So ERROR 4F02 was the location of the chip on the PCB (Row 4, Column F).

@KameraShy 4 күн бұрын

Very logical.

@kaitlyn__L 4 күн бұрын

Ooh, great spot!

@perorin615 3 күн бұрын

there is absolutely no way that's what the error code means

@kaitlyn__L 3 күн бұрын

@@perorin615 I mean, we’d need to see if the causes of those other, non critical, errors also matches the maybe-pattern.

@perorin615 3 күн бұрын

@@kaitlyn__L the system doesn't have access to individual chips. consider that the bad signal went to the working PAL chip which outputs a good signal. How's the system going to know that the signal between the latch and the PAL is bad?

@insanelydigitalvids 2 күн бұрын

A gift from the Universe + a team of geeks + a Master Class in tracing circuits = excellent video! 🙂

@delmonti 4 күн бұрын

....this is better than ANY Netflix series!

@Kwaq84 3 күн бұрын

Oh come on, Wednesday was pretty good and wasn't fu@&ed yet ;)

@nemike42 10 күн бұрын

Is it coincidence that the error 4F02 is the same as the socket that the chip was? U4F ? Did the error actually indicate the failure location?

@CollinBaillie 4 күн бұрын

When I looked in on the Discord, the working theory was that the numbers related to the test sequence. Test phase 4 was named Main. F was Failed and 02 was test 2 within phase 4. So the second (or 3rd, starting at 0?) test had failed.

@NEEC1 4 күн бұрын

It looks like it, but how sophisticated would the diagnostic routine have to be to be able to drill down that far. How about pulling another chip, see if the diag code gets it right. Easy test.

@TheAnkMan 22 сағат бұрын

I am following your channel since someone pointed me to your "C64 left for dead" video some 5 years ago, and loved every episode since then. Same applies to your series. But this one topped everthing before. How amazing is it to get a machine with virtually zero documentation or any information running again. And the community figuring out things needed to preceed. One has skills in this, the other in another subject. All combined results in awesomeness I've never seen anywhere else.

@Colin_Ames 4 күн бұрын

What incredible luck finding those documents. Also, what incredible luck having community members willing and able to search for them. I am waiting with bated breath for part 5.

@MartinsGraveyard 4 күн бұрын

Adrian, I'm so happy that you've decided to do this full time, some time ago. You are perfect the way you are, and watching you is a pleasure, even if I don't get a lot of it. Bounding you to some office job would be a huge waste for humanity. Thanks for the great content!

@Hutschnur 4 күн бұрын

I just can't get enough of this stuff. The machine is a stunning beauty inside and outside. Thank you, Adrian, for sharing!

@jeffvandyke8162 4 күн бұрын

This has been one of my favorite ADB series in the last several years!

@kilgoar 3 күн бұрын

this is now adrian's digital archaeology. love the professionalism in the approach, the keeping of records, and publishing of results. there are some things worth more than a working machine, and this machine is like cracking open a rock and finding a transitional fossil

@wysoft Күн бұрын

I think this is one of the funnest series you've done so far - even if you probably never intended to have to pull so many strings to get this thing to work - but I love these old oddball Unix systems any way. At this point you're almost into the territory of one of those "we found this 100 year old truck in the woods will it start" videos

@anthonyblacker8471 2 күн бұрын

13:15 it can be a daunting task. BUT.. as long as you've done your due diligence and wrote everything down, now YOU are the one who's written out the schematics of all the ICs on that board. What great work Adrian.. it takes a special person to go through all that..

@3vi1J 3 күн бұрын

That's some amazing crowd-sourcing and detective work. I can't wait to see the next steps. And, it was great meeting you today at VCFSW; hope you come back for more panels/talks at the next one!

@godfirnon 4 күн бұрын

This series and your entire description of the troubleshooting in the middle of the video are absolutely riviting!

@vwltfluxcapacitor 4 күн бұрын

Adrian - this is unbelievably fascinating. Thank you so much for sharing!

@bikeforever2016 4 күн бұрын

What a fantastic set of results. Saw you pop up on Usagi's discord and tried to keep up with the unfolding of events, but it was fast. Loving the series. Encouraging me on my vintage computer journey. All the best.

@KameraShy 4 күн бұрын

Truly amazing engineering back in the 80's. Reverse engineering this mystery machine is uber geekdom at its finest. There are no limits as to what can be accomplished.

@rager1969 4 күн бұрын

Wow, you lucked out on that hidden partition. It's like finding the Rosetta Stone.

@maxtornogood 11 күн бұрын

It's fitting you have Rammy off in the corner given the nature of this issue. Lots of excellent sleuthing & forensics finally led to a breakthrough. The saga continues!

@MarkyShaw 4 күн бұрын

This now the Plexus saga! :-) I'm fully invested now.

@exidy-yt 4 күн бұрын

It seems like that whole 'battery damaged' area suffered a failure. I think you have a couple more S and LS logic chips to replace! So happy you have Usagi's discord helping you out. Those guys are fantastic and helped Dave bring a Centurion mini almost as obscure as your Plexus back to full life and emulated and documented. I know you will get this finished, especially with your incredibly lucky find on the HDD!

@WouterR 4 күн бұрын

Wow Adrian, i’m technical and love your videos. This video is really next level, you lost me quite frequently. But the fun you have recovering these old gems is remarkable. Greetings from the Netherlands

@KameraShy 4 күн бұрын

This really is a hard core computer design 101 course.

@brandonbrooks2845 3 күн бұрын

It was a pleasure meeting you at VCFSW on Saturday!! Great job with the Plexus, what a treasure trove of information!!

@pmNCC-1701 4 күн бұрын

An easier and simpler way to remove a chip for replacement is this: Take a very sharp and new side cutter. I keep this cutter just for cutting I.C. pins. Cut all the pins flush to the body of the I.C. The body falls away. Then take a needle nose pliers and a solder gun, heat a pin at a time, and remove each pin from the board. Next, take a solder sucker and remove the solder from each pinhole. Be careful not to overheat the pinhole otherwise, the trace and or donuts from the board will lift off and break... I have been using this technique for decades... =)

@mikebarushok5361 4 күн бұрын

I'm still always amazed when I see people that don't use that method struggle and often damaging traces and plated through holes.

@Groovewonder2 4 күн бұрын

You said you were in contact with the original user of the machine, so it would be REALLY cool to get them on a video call for an interview. Get the real backroom information on the history of the machine and its development/production.

@DanielLopez-up6os 3 күн бұрын

It's awesome that people were so willing to help to make this one work.

@rdog77 4 күн бұрын

The saga on this series is got me hooked! I do a lot of troubleshooting in my younger years, all gone away. This brings me back. Love this channel.

@UCm0i6w5lBlRthCtZEoj99tg 2 күн бұрын

Really loved this series! I'm so glad so many people came together (especially old Plexus folks) to get some of this figured out.

@baronvonschnellenstein2811 4 күн бұрын

Solid progress! Glad to hear you had some good luck w.r.t. a form of original documentation hidden on the HDD as well as getting a line of communication with someone formerly involved in the design/build of the machines - as well as some helping hands in the wider retro-computing community :) Eagerly awaiting the next instalment of this adventure!

@tristanbuckner 11 күн бұрын

This series has been so exciting I ended up ordering Lions’ Commentary on UNIX.

@KevinFarleyWV 3 күн бұрын

This is one of your best videos. I've seen dozens of your soldering fixes, but this is far more interesting to me, a firmware engineer.

@VincentGroenewold 4 күн бұрын

Absolutely mindblowing again. I never cared for PC-like machines back in the day, but this machine is super interesting, so much thought went into it. Love it!

@mistermac56 4 күн бұрын

Great video Adrian! Hats off to the many contributors that are providing great information. It put a smile on my face when the pop up message came up and said that you are in contact with the designer. I sincerely hope that they can give you insight into the Plexus. It would be a gold mine if they still have schematics and/or design information to help you totally resurrect the Plexus.

@calinculianu 4 күн бұрын

Adrian -- this is one of the best video series you ever made. I LOVE IT! I love the mystery and the success story of the community coming together and the plot-twist of the technical docs being ON THE MACHINE ITSELF. This is a great series!! I don't even want it to ever end and I look forward to the next part.

@billyjhamlin 4 күн бұрын

So, with the bodge wires it's actually a seven layer board.

@stamasd8500 4 күн бұрын

And the ATTiny is the 8th layer. :)

@dumpfbrumsel4687 4 күн бұрын

You hit the Plexus Jackpot, what a ride :-)

@CoockieClassiCKeks 3 күн бұрын

Wow, im not the best, speaking english, not ne best at computers, but im sitting on my sofa, listening and watching the plexus series, my mind explodes. I really understand what youre talking about the issues with this thing and it comes with its own service manual, also mind blowing. Troubleshooting xxl,

@Cherijo78 4 күн бұрын

IF ONLY SOMEONE HAD A PDP 11 TO RUN THE CALAY CAD ON... Usagi.... Looks like your mission is clear...

@johnvanwinkle4351 2 күн бұрын

Great troubleshooting! I appreciate you actually trying to figure out what is wrong instead of changing parts and seeing if it fixes it....grin

@ukaszrutkowski8368 4 күн бұрын

This computer deserves its own name. An it should be "Hitchcock" for sure.

@JohnnyUtah488 4 күн бұрын

I always enjoy Adrian's videos, but this series is absolutely EPIC! It's so wholesome to see the community come together to unearth this piece of computing history. Kudos to everyone involved!

@GYTCommnts 4 күн бұрын

This is INCREDIBLE and one excellent example of community knowledge and team work. Amazing! ✊

@michaelhaardt5988 4 күн бұрын

What an overwhelming series of events! That may be the best episode series ever and you had quite a few brilliant ones before.

@gregorymccoy6797 8 сағат бұрын

This is exactly the type of discussion I love. Thanks!!!

@lithiumpro9999 4 күн бұрын

great job.. This is why i love your channels.. Watching you retrace it and even if you fail this is great stuff.. Because we only learn from our failures..

@tinfoilcat 3 күн бұрын

Really appreciating this longer more in-depth format! Such a story! I do like your usual stuff as well though!

@lathans1 4 күн бұрын

I can't remember the last time I was so interested in a series of anything! Or had me that excited and wanting more at not only one, but every cliffhanger! Thank you for all the great content!

@anthonyblacker8471 2 күн бұрын

I MISSED this drop, I've been waiting for the next Plexus video, it's crazy there's like zero info on these things out there, but it's SUCH an exciting machine!! I hope you get it working.. so cool

@digitalarchaeologist5102 3 күн бұрын

One of my absolutely favourite series. Love it. Thanks Adrian

@eekpie 4 күн бұрын

mikeselectricstuff taught me a good way to scan for continuity in a maze. connect your probe lead to a fine metal brush and paint over the board. wire wool if you're a maniac

@javaguru7141 4 күн бұрын

Neat! If you were to make a purpose-built tool for this, maybe a conductive-plastic brush would be gentler on the board 🤔

@TheRetroBristolian 3 күн бұрын

A viewer actually sent that attachment into Adrian a few years ago and he has shown a video using it, so perhaps that is what he used here, or at least he 'could have' as he does have one :-)

@captainsunshine918 4 күн бұрын

Fantastic! I had company over when I saw this video was up... I was quite happy to see them on their way so i could start watching! Great stuff!

@Choralone422 4 күн бұрын

Incredible work done by everyone in the Discord server! I am so pumped to the new developments in this video and those yet to come! It has been so satisfying to watch everything come together to help understand and document more about this machine! So cool!

@perhansson6718 4 күн бұрын

What an amazing journey Adrian! Thanks for making such a detailed recap of the troubleshooting, looking forward to what can be crowd-sourced on the Discord server :)

@lqueryvg666 3 күн бұрын

Loving this Plexus series AND the fact of so many peeps helping you out!!!

@jkeelsnc 4 күн бұрын

Amazing cooperative effort to unlock this system’s operation. I am fascinated by this series of videos on the Plexus.

@GeorgeWMays 3 күн бұрын

Progress. Congratulations. Keep chugging. I'm impressed. Thanks a ton for the video. It's appreciated.

@teekay_1 4 күн бұрын

Outstanding work. A lot of these "mini-computers" from the 80's are lost and forgotten, and since they were before the the internet, there was nothing to save by the time these companies went bankrupt. You're saving a little piece of our computer heritage with these videos. Thanks much.

@johndoe4314 3 күн бұрын

This series is so great. I was hooked by this machine right from the start and how this story unravels is just superb. I love how you get the community involved and that we bring this thing back alive together. And if anyone could have its own emulated P/20 would be soooo cool! What a great series Adrian! Thank you all!

@xavierdemers-bouchard2747 4 күн бұрын

Most interesting troubleshooting and collaboration combo I've seen in such a long time A+, 11/10, 6 stars.

@brooknet 2 күн бұрын

I'm so glad that you made progress with the RAM issue! May I add that I learn a lot from the way that you troubleshoot these complex systems, and it's valuable information to help when I am trying to diagnose issues with my computers. For example, I may need to troubleshoot a SPARCserver (630MP) that I haven't powered-up for three years. It has a real-time clock module that's similar to the one on the Plexus: it's a sealed unit, no way to replace the battery when it runs out. There might be some hints on how to access the battery terminals. All this fun stuff awaits. The trouble with the 630MP started when it was invaded by tiny spiders. 🙂

@chriswareham 4 күн бұрын

Absolutely enjoying this series! The discovery of technical documentation on a hidden partition is incredibly good luck, another little piece of computing history.

@subynut 4 күн бұрын

Super exciting to see it booting further!

@Cubik303 4 күн бұрын

What an amazing journey so far! Can’t wait for the next video!

@chriswoods562 4 күн бұрын

Congratulations, Adrian. I admire your patience!

@morebasheder 3 күн бұрын

I just love the endless enthusiasm that you have for what the vast majority of people would consider to be obsolete junk. Clearly myself and other viewers of this channel are in the same category as yourself. Keep up the good work! Greetings from the UK 🇬🇧 👍🏼

@andrewboothman6363 4 күн бұрын

Extraordinary lucky find with all that documentation! Loved watching this. Thanks.

@CasualSpud 4 күн бұрын

Strength in numbers... good job!

@dr.klipper 4 күн бұрын

I love this Plexus series :-) Can´t wait for part 5 now ... Well done Adrian 👍

@djwaffle 4 күн бұрын

I appreciate that you are being careful with data on the drive. Great work.

@jeromethiel4323 4 күн бұрын

What's amazing to me is a single transistor on a chip can break an entire machine. Considering that modern computers contain millions of transistors, it's amazing any computer works at all. But they do, and continue to work for years and years. Semiconductors are amazingly resilient as long as you treat them right.

@yt45204 4 күн бұрын

Billions

@jeromethiel4323 3 күн бұрын

@@yt45204 Now, yes. But when the Plexus was built? Heck, modern memory has billions of transistors in them alone.

@johnfox4376 3 күн бұрын

You were the one who said that "modern computers contain millions of transistors".

@jeromethiel4323 3 күн бұрын

@@johnfox4376 Captain pedantic to the rescue! Yay! You win the internets.

@yt45204 3 күн бұрын

@@jeromethiel4323 When I went to university in the early 90's, some of our older CS and EE professors had been around in the 1950s when Sweden did a lot of work on early computer systems, and even had the world's fastest computer for a bit. It was interesting to hear them talk about the problems they faced back then. Just like you mentioned, reliability was the biggest one. With electron tubes, they obviously burned out after a while and had to be replaced. But even when they switched to transistors, the reliability issue wasn't solved. Their computers consisted of many thousands of components soldered onto boards, and may boards connected through backplanes and ribbon cables. They had to spend a lot of time improving soldering techniques, connector reliability etc. The huge deal with integrated circuits with many transistors was more about reliability in the beginning, rather than the number of transistors they could pack in a small space. With ICs, they finally got the computers running more reliably. But even today it is an issue with memory bits flipping due to background radiation. We should really all have ECC memory for everything, but the manufacturers have chosen to limit that on consumer devices so they can upcharge their servers.

@andrewrfpi Күн бұрын

My goodnes, you are the man! what fab diagnosis! good luck with the next steps debugging the multibus / clock issues.

@tony359 3 күн бұрын

I thought I was playing an Adrian’s digital basement video and instead a ‘Columbo’ episode turned up! I love this and can’t wait to see the next step!

@jedglover8245 4 күн бұрын

I worked on UNIX systems like this in 86, amazing job to get it to hopefully the verge of working again. Interesting that 39 years later 4kb is still the default page size for Linux.

@CH4NNELZERO 3 күн бұрын

Cool. Were you working on the hardware design or the software back then?

@jedglover8245 3 күн бұрын

@@CH4NNELZERO The company I worked for did software for insurance brokers, the system we had was a Zialog Z8000 based UNIX, very similar besides that. I think it was tested as a possible new platform for customers, but we ended up using Thoroughbred Basic on IBM ATs. The systems being replaced were Mercator systems running Mercator Business Basic, that was identical to Thoroughbred Basic, all ISAM table storage.

@No-mq5lw 3 күн бұрын

Think that's mostly because x64 still only supports 4k paging. M1 supports 16k.

@8bitcpu 4 күн бұрын

Excellent series. Looking forward to seeing what comes next.

@Eremon1 4 күн бұрын

It only just occurred to me now, but with all those bodge wires, is it possible this is an early model? Perhaps it never made much of an impact in the market not selling many. Thus the reason there is literally no information online about this particular machine. What an amazing find on that original partition. The fact it survived all these years is just mind boggling. I don't know why, but when an old forgotten machine gets some attention again I find a lot of satisfaction in that. Cheers.

@dcfly 4 күн бұрын

Adrian, I love your videos. Unfortunately, I live in a small apartment in the city. Believe me, I have exhausted my space with old computers. Your channel allows me to live vicariously through you and your troubleshooting. I am fascinated with the computers you get to work with, even though I have no room for them myself. Your troubleshooting methods are exactly what I would do (or better in most cases). Thank you so much for your videos.

@greenmoose_ 4 күн бұрын

I have no idea why I am so invested in the story of this machine but I clicked on this one fast when I saw it! cant wait for the next instalment!

@johndray2326 3 күн бұрын

Loving this series... such luck with the documentation!

@SidebandSamurai Күн бұрын

This is majorly cool. Adrian, you are awesome. You could write a book on this subject now, because you are the SME (Subject Matter Expert) all the people who own plexus's will come to you for your information. Good luck in making this old machine work.