What is this rare multi-user UNIX workstation? (Plexus P/20)
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- Опубликовано: 24 май 2024
- What we have on the bench is a Plexus P/20 dual processor multi-user UNIX computer from 1985. This was likely designed for office user and support 8 concurrent users in this configuration, with up to 16 possible with the use of an extra I/O processor card. This machine doesn't seem to be documented anywhere other than a simple brochure (link below) so let's see if we can unravel some of the mysteries of this machine.
Part 1: This part
Part 2: • First power up of the ...
Part 3: • Booting UNIX on the Pl...
Part 4: • We made some unbelieva...
-- Links
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 
Наука
Thank you to everyone who has reversed the root passwords I briefly showed. One of my patrons jumped onto it when I first released this video to them and managed to provide them. :-) Also check out my Github repo with some technical information and various documents which have been turned up so far on these Plexus machines: github.com/misterblack1/plexus-p20
i wonder if it will run in Linux... like that HDD or image is still compatible with a Linux Mint for example??... if you can mounted and see it in GParted and stuff....
@@Ramdileo_sysThere is no linux mint for 68010.
I feel so old compared to you :-/
Ofcource we had email on unix long before Internet.
The machines had uucp for mail and news and uux for remote commands.
I also used slip to create network over serial modems.
Communication actually worked better than now, it was peer 2 peer, no central master for the world, no spam or viruses and no ads or censure.
Those who was connected to Arpa or Internet often had servers that translated mail to ftp so one just added it to ~.remote and sent a mail with ls -lR and the server returned a list of all software.
Then it was just to write a macro that sent a get for each file I wanted.
No ask for cookies and no garbage. We Unix admins was like a famely with moral and honor.
Please put the hdd image up somewhere so we can add to MAME. Thanks.
Two of the references appear to be backup password file entries that have blank passwords. As others have said you could edit a copy of the disk image... with the twist of copying the devroot one into the others and have gotten an empty password login.
That looks a whole lot like a gateway drug to the large scale minicomputer world.
Welcome!
Yes, and it is a little bit dangerous. I've been there - I'm still there - and I like it!
Exactly what I thought the second System V rolled or of Adrian’s mouth… 😂
The crossover everyone needs... Dave and Adrian working on something. :)
Yes indeed! Awesome video, especially the HDD sleuthing. Looking forward to more!
I love a bit of computer archaeology. the Centurion series of videos is awesome and i can't wait for the next Plexus installment
Finally! I worked for Plexus from 85 to 88. This was the smallest Plexus system. It was code named Robin. It competed with the NCR Tower.
Wow that must have been really interesting!
Is this the same plexus of the neenah variety?
@@x_x_w_ Nope. Plexus was founded by Bob Marsh and Kip Meyers. Both came from a company called Onyx systems which started out making machines to run CP/M. Marsh wanted Onyx to move into the UNIX market and negotiated the very first UNIX license with AT&T. This resulted in the Onyx C8000 which was based on the Zliog Z8000. Onyx manufacturing was run by a young Scott McNealy.
Eventually Onyx decided not to continue selling UNIX systems which prompted Bob & Kip to found Plexus and McNealy moved on to Sun. Plexus originally used Z8000 chips but quickly adopted the 680x0 family. Plexus also developed a networking scheme called NOS (Network OS)which was a lot like Sun NFS for sharing files, but unlike NFS you could also access any /dev device like tape drives and serial ports over the network.
Mulipeter you must get in touch with Adrian... Was you behind any of the builds of Plexus?
@@rfxtuber I’d love to speak with him! I was actually in technical marketing and was very aware of a lot of the design aspects. I’m hardly an expert on design, but I think I can fill in some gaps.
And THIS is one of my favorite type of content. Unknown machine, unknown architecture and unknown soft. I can't wait for another episode.
now lets reverse engineer the machine
ABSOLUTELY!! +1
About Plexus Computer, Inc. : It started operating in 1981 and in 1988 sold its Unix and hardware side of their business to Motorola. By this time they 've already gone up to the 68020 processor with up to 48 MB of RAM and adopted the VMEbus in their P/95 product. They kept on developing their expensive and niche software imaging products under chapter 11 protection (bankruptcy) until 1989 when they finally sold the remaining software assets to "Recognition Equipment".
Looks like you can still check out the building on Google maps, and Cypress semiconductors occupies the building now? Interesting building.
Recognition Equipment was acquired by Banctec and in 2007 was reported as still selling products via their Plexus Software division. See www.sec.gov/Archives/edgar/data/318378/000104746907006209/a2179097zs-1.htm
@@dparks256it's now "Infineon".
So cool to see one of those again! I worked for a Circuit City location years ago that in the 2000s was still running serial terminals over a PLEXUS server. I do know it was based on 68030 CPUs, with a pair of 160MB SCSI drives in mirror. But it so happened that I was the only non-corporate person who had root level login on the command line. The rest of the store was based on a locked menu for sales, inventory management, etc. I had just quit consulting and as the ONLY person on site with Unix certificates, I got saddled with emergency on-call. It never happened, but oh that brings back memories!
so you're why they closed down, never answered that call, huh!?!?!? haha aaaaa i liked Circuit City but I LOVED CompUSA back then
Wow that is brave. Running daily ops on a 15-ish year old server with MFM hard drives. Now, to feel old, that would be like running a business today on Pentium 4 servers. I have, indeed, recently seen P4-era hardware at a few businesses I work with. But they're always either "oh yeah, we never took that out of the rack, I'm not sure if it does anything anymore" or "that's our sandbox."
@@nickwallette6201 That has fully converted to SCSI by then. But it was still 68030’s which was hilarious. The server had been in place for 15 years before I ever was employed, and outlasted the company. I walked out a year after the changeover, when the company went from commissioned sales to trying to clone Best Buy. It clipped all management off at the knees and left every store hemorrhaging. Going from “we trust every one of you to do your best” to “fark off, you’re just a number and can be replaced” ruined them.
Funny enough, I we’ve to work at OfficeMax 10 years later, then corporate change, walk out on my part, and then the company collapsed. Funny, that. Why I don’t work for anybody but myself anymore.
@@nickwallette6201that’s amazing. I know there are business that using computers much too old than they have right to (my dad was doing IT for that company). I worked for a company a few years ago that used a janky Windows CE device for package tracking.
Should get a solar panel to run it off of, so it can be a solar plexus.
That just made my day. Thank you! ❤
Bravo
LOL! ^-^
Off to pun jail! 😁
You've done stellar work today. You can have tomorrow off :-)
That is BEAUTIFUL COMPUTER. Wow. This is the way we all thought our own computers would look someday. I think old computers had a way of looking more futuristic and capable than they really were...and now that computers are as powerful as the old machines looked, they're more boring to look at.
It's all those ICs. Modern machines have condensed most of the circuitry into a few ICs that just need some support passive components (capacitors, resistors, etc.) to work. Old machines didn't have that level of integration so it looks like there's more going on.
Strictly speaking, this is not a workstation. When I was at Plexus, we referred to it as our entry-level departmental deskside system.
"Would you like to use the entry-level departmental deskside system?"
"Would you like to use the workstation?"
Yeah, pretty easy to see why that didn't catch on! 😋
@@RetroJack Workstations are single user graphics machines. This machine was designed to drive a dozen or so dumb terminals. The term “Server” had yet to be coined.
@@MultiPetercool That wasn't my point.
Still firmly in the era of corporate computing = large computer and a load of terminals. I guess the "deskside" is why they are marketing it as quiet. You don't need a whole separate room to put this in. Wondering if companies in the mid/late 80's, employed sysadmins to set up and maintain these things, or if that was included with a contract when they purchased the computer.
@@user-rx8lz6yz4f All of the fledgling UNIX companies at the time sold through a local reseller who typically would install and maintain as well as provide first line customer support.
The architecture of that machine looks familiar. Back in 1983, I received a tour of Altos my late brother arranged with his friend who worked there. After the tour, I bought an Altos 586 directly from the factory. The CPU is an 8086 with a Z-80 I/O bus. It still runs fine and I too study the design directly from the ROM. Fortunately, I have all the floppies to load the Xenix operating system and software, backed up to modern media via Dunfield's ImageDisk. The Winchester drive still works, but I'm preparing the system for a time when that may not be the case.
I’m not sure how I can emphasize enough how much I want you to create more vids on this system. I was riveted the entire time. Please!! And thank you! 😊
Gotta say, I love how you're branching out in the types of tech you feature in your videos. Don't get me wrong, I'm a man of culture so I can watch Amigas and Commodores and PCs all day, but there's something satisfyingly exotic in UNIX machines and stuff!
When encountering a key cylinder like that, the best approach in my opinion is to order a replacement key off eBay. Usually the number stamped into the cylinder next to the keyhole will tell you all you need to know to find the correct key. In this case it is an EAO 311 selector switch key.
Yes, it is a shame to destroy the lock. He should have taken it to a locksmith to either re-pin the cylinder or cut a new key.
Also, btw, those key cylinders are really easy to pick. You just usually have to jiggle the pins. I have to do that on this old AS400 when I lost the key. I am not skilled enough to open a proper door but a good 15 min video can get you good enough to open those crap locks.
I'd probably just replace the keyswitch instead of bothering with figuring things out 😅
About mounting the partition: you can do 'losetup --partscan -find --show /dev/whatever' and it will create loopback devices (/dev/loop?p*) for you pointing to each partition. You can then use them like any other.
I tend to use qemu-nbd, which probably knows even more partitioning formats (and disk image formats), you first need to modprobe nbd, then qemu-nbd -c /dev/nbd0 disk.img
I just love how Adrian gets as worked up, as I would, when recovering/saving a disk image.
Okay, I'm hooked now. This brings me back to all the various non-working multi-user serial UNIX systems that I encountered during my career, but never had the warrant to explore for my own edification. My own university experience had UNIX on VAX machines that filled entire rooms, and 9600 BPS serial over phone lines. It must have been heady stuff for a small business to have multi-user UNIX access without having to buy, lease or purchase time on a million dollar mini. Truly the first steps towards LAN personal computing that we know today.
There is one particular East German PC compatible computer- the Robotron A7150- which is a Multibus system. It has an 8086 processor and a full 16-bit bus, and some of the cards have a Z80 on them for I/O. A Unix-like operating system called MUTOS1700 was written for it.
That thing is GORGEOUS!
Must have been incredibly expensive
@@PaulMiller-mn3me about 15 to 20.k depending on configuration (1988)
Qoffice was an office automation suite from Quadratron Systems. Main feature was a word processor, but it also had EMail and database. I don't recall it having a spreadsheet. It was really slow -- optimized to handle many concurrent users, rather than being good for any one person. For example, it didn't try to optimize screen updates, because that would require CPU cycles. A full redraw could be offloaded to an I/O processor.
Thanks for the background information! Qoffice (or Q-Office) was one of the applications ported to Acorn's ARM-based R140 workstation in 1989. Since the R140 didn't have numerous serial ports, I could imagine that the idea was to interact with the software using terminals over the local area network, this being either Acorn's own Econet or the more familiar TCP/IP over Ethernet.
I have a feeling this computer was stored on its side for years and years. It's lucky, but looking at the way the battery leaked, it it were stored vertically, it probably would have done a WHOLE LOT more damage.. I'm only at the part in the video where you've removed the battery so far, but man honestly that seems pretty lucky! What a find Adrian!! This machine is SUPER well built.. very amazing, I'll bet it was like $10,000 or more back in the day. I don't recall if you said there was a price when you introduced it.. what a machine!
It sure looks like it's built like a tank. They sure don't make 'em like that anymore.
The main board reminds me of the inside of an arcade cabinet, I've never seen such a dense amount of ICs
It's a battleship a bit like the Apple Lisa. 68k technology "done right".
The Dutch equivalent of a college I went to, introduced a 680x0 based UNIX system in the year I started my Computer Science course and it was amazing, all we had seen at school up to that point were Apple II's and the usual Commodore VIC-20 and C64 and the occasional IBM-XT. I was reading The Cuckoo's Egg book by Clifford Stoll at that time, which showed a very simple script that you could run on an open terminal, tricking people to enter their username and password, I managed to sneak that in to a teachers session and gained root access to the system, such good and fun times. When I started working I landed a job at a company that rented out system with all possible flavors of UNIX, so really loving this video and looking forward to part 2.
Resistor board is a bus terminator board. You see equivalents in early NCR machines, early ALTOS systems, and different generations of DEC PDP-11 (unibus) and VAXes (multibus)
You don't use 2 dozen power resistors on a bus terminator board.
I wasn't sure if I would just bounce off this video. I've never had any connection to UNIX or any kind of terminal based computing. But I really enjoyed this! And very much looking forward to the story unfolding 😁
unix is the one true os. seriously early windows nt was just a bad copy of unix. its a 50 year old os thats still widely used.
@@macgeek21 You sure about that? Windows was more of a Mac clone than a Unix clone. Unix didn't have the GUI interface that early Macs did.
@@rommix0 Well, they all cloned from the 1973 Xerox Alto. Even more, Steve Jobs himself in 1979 arranged a visit to Xerox PARC to have a demonstration of the machine for inspiration.
@@rommix0He said Win NT... In the early days there where 2 main windows flavors WinNT and Win 3.x. Ultimately WinNT did take over the world starting with Win2K and XP..
For unix that old passwords are probably saved with DES, not MD5. At the time MD5 itself did not even exist.
It v2 of SysV, they are salted password not DES
@@GrandpasPlace Unix crypt(), ya? I thought that was a way of using DES as a sort of salted hash function?
@@GrandpasPlace With what algorithm? I have always understood, that algorithm used was DES... Basically Seed + password was used to encrypt known plaintext
Read this.
Compared to what was shown on screen it was salt, without or before the sha256.
en.wikipedia.org/wiki/Salt_(cryptography)
@@logansorenssen No, in later versions it would salt then sha256 hash the password but compared to what was on the screen, that was ancient and just used salt.
I used to work with old IBM RS/6000 systems. They booted their OS installation off the tape too. It was quite common back then.
Old RS/6K junkie myself. Worked on the hardware side then on the AIX side while in Austin.
Now THATS a motherboard.
getting close to a mothership at this point
@@Kosakate I guess its a logic board, not a motherboard. But still! Thats an all time, could fit a large pizza on it.
Indeed, and more likely an absolute pain to fix.
@@ChairmanMeow1 I wonder, what's the difference between "logic board" and "motherboard"? when I look it up on wikipedia, both of those terms redirect to the same page, "Motherboard".
@@proCaylak Im not totally sure, maybe the term just changed over time. I just googled it and I was wrong! "Logic boards are the small component of the motherboard which is responsible for the connection of all the components of a computer." says chat GPT
All the "N^NuNV" strings are from executable code. The Motorola's typical assembly/machine instructions happen to look like N^ as the function return instruction and NuNV on the next function's starting instructions. This is why this string appears A LOT in string dumps from 680x0 code.
I live in UNIX & Linux for my professional and personal life for the last 45 years! I was so excited to see that this computer was that kind of OS! 🎉🥰
I actually love Unix and Unix like osses! They are great
Adrian is attempting a Usagi Electric type of revival. Look at what Usagi Electric did with Centurion mini computers 😊
I also got Usagi Electric vibes from this video .... not a bad thing I love both channels.
Too bad Adrian is lazy and gives up after 10 minutes instead of researching something. David will drive across the country to interview engineers and retrieve parts to get something like this going.
@@humidbeing Pretty damn rude. Give Adrian space to explore this system. Can't wait for the next installment.
@@humidbeingyou do realize these videos are edited and aren't live?
@@humidbeing How exactly do you think Usagi amassed so much information about the Centurion? Oh, right, ASKING HIS VIEWERS FOR HELP. There's nothing wrong with using your audience's reach in a positive way to try to dig for obscure information oftentimes impossible to find as a one-man team. I dunno if you've actually tried to research Plexus computers, but they're not exactly easy to find anything on, considering this is like one of two machines known to exist on the planet...
I really enjoyed this episode, I hope it's the start of a mini series! I'm more invested in this than I was Game Of Thrones :)
It's crazy how they took the time to make a mainframe that almost no one will ever see look so nice. That thing is a work of art.
Probably impresses the executives or their representatives at trade shows.
This is not a motherboard. This is the Mother of all Motherboards.
"That's no moon, that's a motherboard! "
Soooo…. A grandmotherboard? ;)
literally on the edge of my seat!!!!
The disk is probably one of the standard Unix file systems. If that's SysVr2, then I don't think they'd added the VFS at that point, so there was only one supported filesystem (known as FS) and it was baked into the kernel. FFS came along with BSD 4.2.
Indeed, you can identify the file system with "file foo.img".
Dang it... What a cliffhanger! Please do more on this!
I'm only at 19:13 so you may figure it out later but I'm pretty sure the wire screwed on to each power supply at the top is meant to be a handle to lift them up and out, might have made it a bit less sketchy
This might be the best video you've ever made, Adrian. Great to see you starting the restoration of such a rarely-seen type of computer. Hats off to you.
This is SO cool. Great work so far, Adrian!
This is so cool. Love the design and construction of this piece, and your energy to understand it and get it running.
I was on the edge of my seat from start to finish, I can’t wait for the next episode on this machine!!
Really interesting seeing the more rare/unusual systems, great work, looking forward to seeing if it actually runs
Man, one can really hear and feel the joy and excitement in your voice!
Great Video, Thank you!
That is an awesome looking system. I can't wait for part 2. Been a fan of your channel for years and I love these vids where you find older systems that are kind of "lost" and try to restore them.
This was was really enjoyable to watch. I really felt like I was there with you. Nice job!! :D
Try "losetup -P" option next time, it'll trigger the kernel to scan for the partition table on the loop device after creation - and then create /dev/loopp style nodes where you can access individual partitions and mount them.
Awesome save. Can't wait to see part 2.
Oh i sure hope we get more videos on this computer, love it!! Thanks!
Fantastic video. I can't wait to see this progress.
Can't wait for the follow up! I love old UNIX stuff, thank you for sharing!
The 68000 and the 68010 both have a 24-bit address width which allows them to address up to 16MB. Actual memory capacity will depend on the I/O subsystem used. There was actually a 68012 which had a 31-bit address.
If I had one of those SMS intelligent disk interfaces in a computer I'd try to get one of those high-capacity Maxtor MFM drives for it.
So... expanding: The 68010 was special for workstations for two reasons: 1. two instruction cache ... sped up loops of exactly 2 instructions. 2. ability to restart an instruction after memory access failure --- allowed use with virtual memory controllers. There were a buttload of small unix vendors in the early 80's. Everyone wanted the success of the minis from the '70's. It seems that very, very few survived.
I was going to add this specific comment. I worked on a system VERY similar to this for a company called Data Systems Design (who invented the Dec Disk Drive clone space). The wanted to compete against Fortune Systems and we came up with a dual processor system - with a System/Job Processor combination. The Job Processor was Virtual, i.e. used the 68010. I implemented a Memory Management Unit for it using the 68010 - we had engineering samples of same - worked well! The one trick we did was use a 64 bit memory bus - with a single line cache in between the 16 bit 68010 and the memory. So we could get 3 out of 4 instructions with no wait states. The system was going to run Unisoft Unix System 3 (this was 1982). They ALSO had a Multibus interface because they were after all a Disc controller company and thought Disc centric. Note that Multibus is little endian, while the 68K is Big Endian - this causes its own problems - mostly in performance.
I think 68010 also had some extra opcodes®isters that made virtualization easier.I seem to remember it was not quite 100% backards compatible at least on Amigas?
Sped up 2-instruction loops? Wow, that must've made the busy-wait loops execute so much faster! haha ;-D
@@nickwallette6201 Short loops are quite powerfull on CIsc machines like 68k
@@DIYTAO I had a 68010 in my Amiga --- it was one of my very first upgrades. Made about 5% difference. Even when I had a 68030 board, my fallback was the 68010, not the original 68000. It was 100% compatible. Never had a problem with it.
Love your enthusiasm. Great content.
thank god that part 2 is already out, that cliff hanger is insane!
I lost the lust for computers many years ago, and your videos kinda make it so that I don’t miss technology. Keep them coming Adrian.
That front panel is unforgettable. I saw one that was non operational once on the bottom shelf of a storage rack. Can’t remember where exactly but still remember this thing catching my eye. Reminded me of an old movie prop. Love it. Thanks for the nostalgia!
I’ve narrowed it down to either the headquarters for a nursing home chain or a mega church. I used to work as a freelancer and contracted to multiple IT firms on the side back in 2009-2012 and they all kinda blend together now.
Wow! This was exotic! Loving it! Can't wait for the follow-up! Thank you Adrian!
I was on the edge of my seat during the disk read :o really good vid!
Regarding /etc/passwd. You can easily override the root password when (if) you boot in single user mode, before the entire Unix is run at multi-user boot level. It would mean editing /etc/passwd and simply setting the password field as blank between the colon separators for the root user. Of course, that relies on a whole bunch of prior steps working correctly to get it to the point of beginning the boot process. Generally the approach is when the boot device is specified by the ROM monitor (i.e BIOS), the boot level is typically also specified. This is from memory, from general Unix/SCO/Xenix principles, so Plexus Unix SysVR2 will probably have it's own specific incantation to specify the boot level.
Or, just modify the /etc/passwd in the disk image with an empty hash. No boot level gymnastics required.
@@RussellSenior yes true enough, assuming Adrian or anyone else is able to access and modify the disk image copy with another non-Plexus system. As others have commented, there was really only one disk format file system “FS” in use on Unix SysVR2, so in principle, it should be possible to access and mod the duplicated image if you can mount it on a Linux system as a sysVR2 FS volume. Assuming Plexus didn’t change the file system format in its implementation.
That really WAS nerve-wracking! How awesome that it worked... What a beautiful and well designed machine! A great video, thanx... KS.
That case is so rad, not gonna lie if I ever found one (and it didn't work) it'd make an awesome sleeper.
Just FYI, saying that in a group of retro computer enthusiasts is sort of like saying you want to chop down the oldest living tree to make some awesome carved beavers for your front porch.
@@nickwallette6201 Oh I'm well aware, that's why I specified that I'd do it to a dead one. And as much as us "computer enthusiasts" would love to save every vintage computer on the planet, some are either undesirable or just lost causes. Just like a Mac Classic I found a few months ago that had such bad battery leakage the entire motherboard had turned to a flaky mess.
Great Stuff enjoyed this video Looking forward to part 2
Pretty cool! I don't remember ever seeing a Plexus. I did get to play with a Xenix system in the mid or late 80's. I don't remember what brand the system was, but it was similar in size to the P/20. And yes, it was MUCH more quiet than the Pr1me Minis that the college was running on at the time. I could hear the minis at the far end of the hall if someone opened a door to the computer room.
That was excellent fun! Can't wait for the next part!
Super interesting video, can't wait to see part 2...
Reminds me a lot of an Altos system that I worked on a couple of times. It too was an ASMP design with separate CPUs for different functions. It supported 20? users in a real estate office. It wasn't unusual for programs to only exist once in physical RAM but be mapped multiple times into individual user spaces so combined with the far smaller program size compared to today's sizes it was possible to do quite a lot with very little RAM.
Wish I knew more about Altos systems. In the late 80s used to connect to a chat system over X.25 called QSD, and it run on an Altos.
1) "resistor board" is a bus terminator 2) you can take key switches to locksmith and get keys made. Often they can make a key just from the number that is stamped on the lock. 3) I fixed a power supply from one of these back in the 80's. Customer brought the P/S in... as I recall it needed a transistor that had shorted, taking out a resistor and replaced a couple caps that were out of spec.
They don't use power resistors on bus terminators. 11:45 If you look at it, it is clear it has 8 parallel strings of 5 resistors directly across one of the power buses. The card even says "POWER BOARD". There are no data bus lines on that card.
Oh wow, incredible video! Can't wait to see more about this thing, hope it can boot!
You bring some really interesting tech
Wow, really impressive that this 40 year old hdd was readable without new errors!
Cant' wait for the next part! Old unix systems are exciting.
I loved this video, cannot wait for the next upload! Want to see that beast booting up :D
Fantastic video - and a seriously gorgeous computer from the mid-80's. I grew up cutting my teeth on machines like this... We had plenty of Unix terminals and VAX machines going back in the day.. They ran everything from dial-in, printing, dispatch control, rates and parking fines... We had a Novel Netware system too - and we had it all nicely integrated.
I keep forgetting just how small all the disks were back then....
Thank you for the vid, your passion is infectious ^_^ On to the next one for me
I *think* I once read about these Plexus Unix machines on the ancient Internet. I remember reading that the 68000 / 68010 didn't really have much ability to handle errors elegantly, so you couldn't get a core dump to help debug if your program crashed the machine. So Plexus (at least I think it was them) used the second CPU read out the state of memory and write it to disk.
37:00 You can mount the partition by stating the offset, in this example with "mount -o loop,ro,offset=8704 image.img /mnt"
Adrian, i am at a low point in my life and your videos help me toss my cares away for a little bit. Thanks!
This is computer archaeology ^_^
Back in the '80s we had a similar Unistride / Wyse system with 68010 with Unix system V and later SCO
and a bunch of tty terminals that we used in the IT lab to write COBOL and PASCAL programs 🙂
That case is absolutely beautiful
In the late 80s (probably a year or two after this computer was made) I used a Silicon Graphics 4D/20 workstation. It used Irix, which was also a SysV flavor Unix, and yes, it could boot off tape into a barebones diagnostic system that could be used to format the hard drive and copy the OS onto it. You can try hacking the passwords (not really "decoding" them) but if you can edit data on the drive, then you should be able to just delete them and leave them blank to log in with no password. (oh, and "opasswd" is the backup copy of the password file; each time it's edited the old file is saved as opasswd and the new one goes into passwd.)
5:30 To be more precise, Amiga supports more than 8MB: up to 2MB of CHIPmem + 8MB of Fastmem + up to 1.8MB of Slowmem + eventually some unused space utilized by 3rd party cards. In A600/A1200 you can have around 13MB of RAM with standard 24-bit address CPU's. Expansions with 32-bit adress pins CPU's can have theorethically close to 4GB of RAM.
It's really cool to see a vintage Unix computer. I hope the computer works.
Awesome video! I'd love to see some more Unix-related content (OpenVMS would also be really cool to see on this channel). Keep up the great work Adrian!
Adrian, I have several SCSI Fujitsu drives from that era and they still work great. They were/are known for make some of the best hard drives. When I heard you say it was a Fujitsu drive I figured there was a very good chance it would work. I’m enjoying the non-standard computer content. I used to run a multiuser Unix system back in the 80’s
Has a tape unit, 80s Unix workstation confirmed
Well into the 90s, even, if the plethora of Sun 411 external SCSI tape drives on e-bay is anything to go by.
@@JeremyLevi it’s not a workstation. No graphics no mouse.
This isn't a workstation. It's a Unix based multiuser timeshare system.
great work on the drive imaging, that was quite interesting and definitely a nail biter!
Cannot wait to hear more about this. We’re starting to get closer to the workstations that my father used, I think.
49:50 I'm no expert, but I don't think it's MD5, I think it's the original "crypt(3)" ... the first two characters are likely the salt. You can attack it with 'hashcat -m 1500 -a 0 passwd.txt dictionary.txt' (1500=descrypt)
I tried a couple of dictionaries without any luck though, but I had to transcribe the passwords so I may have gotten something wrong... or this needs a bit more time and brute force.
Probably easier to just overwrite them in the image with a known password hash.
Wild, never heard of this machine and I was obsessed with Unix machines and multiprocessor hardware in the 1980’s, owned an Altos MP/M, SGI Iris 4D/780gt and Apollo DN460 (still have all except for the Apollo), almost ended up with an AT&T Pixel Machine.
I remember playing with a ONYX Z8000 Unix system 20 years ago. Picked it up from a scrap yard by weight. It stopped booting but I eventually found the importers in South Africa and they loaned me a set of Unix installation tape cartridges. There were all sorts of computer manufacturers back in the day, most have disappeared and now we have very few brand names due to the standardisation lowering the cost of making clones.
Looking forward to seeing it boot!
I think this is the most interesting and nice beige box I’ve ever seen, even in a video.
the joy on your face was magic, a fab video Adrian
Wow this machine is is very sophisticated in comparison to the IBM PC'S and compatibles you work on so much of the time.
I was the software and hardware admin of a large installation of Sun, HP and IBM Unix systems during the time of that Plexus. I'm very familiar with many of the design elements of the case, software implementation(s), etc. I was told by a number of Sun hardware techs that all the mentioned companies had vast amounts of engineer 'swapage' in the 80s. Most companies never cared about NDA agreements during that time as everyone was trying to build their base of customers. Employment NDA came later, or at least were enforced later.
I absolutely loved this video Adrian. It was worth watching just to see the sheer joy on your face when you made a successful image :-) These rare systems are fascinating pieces of history too. Makes you wonder why on Earth they would use a SCSI interposer rather that an actual SCSI drive. Looking forward to the next instalment.
Probably so that higher end models could use ESDI drives without respinning the motherboard.
@@ChrisSmith-tc4df That makes more sense.
@@taffeylewis Also, I forgot that the same interposer also runs the floppy and tape drives.
We got Unix workstations at the office I worked in when I was a young lad, these replaced the terminals and our mini computer, they were not as nice looking as the terminals though, the keyboards and monitors were just black and grey, whereas our old terminals and keyboards were cream and orange.
We had custom software running on them.
If your workstation lock is like the one I used then any computer key will unlock it. LOL, my bike lock key unlocked mine!
really cool video Adrian
Cool stuff, Adrian! The prior episode standing up a terminal rather hinted you might have got hold of a mini computer and I called (or hoped for) a DEC ... This truly mini minicomputer though is rather intriguing.
Off to a promising start (except the butchering of the key lock switch) being able to get an image off the HDD 👍
Hopefully, a few more ppl familiar with these Plexus systems surface ... and can provide or point you at some more software and doco :)
Nice. :) The ipcrm command is for removing a System V IPC message queue, shared memory segment or semaphore. These can be used for communication between processes. One process sends some data, which another takes from there. Is maybe simpler than sockets... E.g. SMS text comes from the web, sent via some other background process.