The Ultimate DEC Rainbow and a PDP Question for You!

[@UsagiElectric]

Regarding the RegisDemo and color demonstration, the RX50 actually damaged the disk (it was an old Wang disk that was in rough shape anyways), so I need to grab a new disk and the Greaseweazlke and write a new disk before I can test it again. I just didn't get around to it for this video. I've had good luck with RX50s not needing a clean in the past, just had a bit of a swing and a miss on this one is all!

[@Scott-i9v2s]

Oh. OK, that answers my question re the colour demo. Thx & Good Luck (NO sarcasm intended!) with writing a new disk.

[@cda32]

Parkes Observatory is still run by a PDP-11. Make a scale model of it

[@RonJohn63]

@@cda32 lets hope they've virtualized it.

[@rfburns5601]

Hey! We don need no stinkin' rainbow! I wanna see you mining bitcoin on the G15 Ha! Just kidding; enjoyed the video.

[@bretwashere]

I was wondering why it wasn’t demonstrated, so thank you for explaining why. lol.

[@VorpalGun]

I would love to see original Unix on the PDP-11.

[@landspide]

Built from original source code!

[@jazzathoth]

There's an online emulator you can run early unix and a number of other oses on pdp-11

[@c1ph3rpunk]

@@jazzathothit’s nothing like smelling air moving off real steel. Virtualization is great, use it daily, but it doesn’t emulate the physical experience which many of us adore. Hardware problems are what drives much of it, it’s not a hindrance, it’s the fun part. Sometimes the journey IS the destination.

[@classicnosh]

@@c1ph3rpunk I feel the same way with my Apple II and Commodore 64 emulators. There's nothing like hearing those old floppy drives working.

[@lawrenceshadai4966]

IIRC DEC had made Concurrent CP/M an option for the Rainbow after launch. Multitasking was impressive in 1983/84. It really shines as the ultimate CP/M box.

[@bobdinitto]

Chung Eng developed Concurrent CP/M for DEC and one day demonstrated it for me. I worked with him at ADE in Newton before we both later worked for DEC. He was quite a funny guy and very smart.

[@reneboeije3257]

@@bobdinitto @lawrenceshadai4966 Multitasking CPM was called MP/M and was available before '82. And at that time there was also a multiuse 8 bit OS, called OASIS. I ran it on a 64k 8085... Networking for MP/M was possible using HiNet, using RS485 between the CP/M stations.

[@virtualinfinity6280]

Great video, as always. As for the PDP-11/83, I'd set it up as the "ultimate BSD PDP-11, running a proper 2.11Bsd. Bonus points for stuffing it with a network-adapter and have BSD setup for proper networking. The software isn't hard to find (tenox archive et al) and installation instructions are also available. That would also be a timeline-correct setup. And it would be absolutely awesome (yes, I like Unix since about 40 years :)

[@jeremybarker7577]

Former DEC engineer here. The part you think may be a delay line almost certainly is. DEC's part numbering system uses the first 2 digits to indicate the general type of part and 16 is an inductor/transformer which includes delay lines. Also the manufacturer's part number starting PE indicates a device made by Pulse Enginering who were a major supplier for that kind of thing.

[@markshade8398]

While I was in college, about 1988, the company my mom worked for was selling off all of their DEC Rainbow computers. She bought 2 cpu's (1 with color and 1 with monochrome), 1 with a hard drive, 1 without, 1 with the RAM expansion, 1 without and both CP/M and DOS. She also got 1 dot matrix printer. I combined the 2 for the most of everything possible, later bought higher capacity ram chips and maxed out the RAM. I used it for sevral years then sold it to an East Coast company that was buying them up at the time. But I learned a ton about pc's, using them, working on that one, and about had drives and other things.

[@christo930]

Do you know if it is actually PC compatible or is it like the Tandy 2000, really crappy compatibility?

[@markshade8398]

@@christo930 more like the T2000. But it is worth pointing out that in both of those cases, the industry standards were not really set yet (still PC wars going back then with many differing options) and if a PC was 100% IBM compatible at that time it was illegal and got sued to death. (That is why the Tandy 2000 wasn't 100% IBM compatible. IBM sued anyone who was and the bigger the company the bigger the suit. Compaq got stuck in a long drawn out suit... For years. Tandy and DEC would have likely been the same.)

[@tarajoe07]

Drives me crazy, I had one of these in the 90's but didn't know what I had. Long gone

[@lorensims4846]

I had been reading about the DEC Rainbow in the computer magazines at the time, and it was definitely on my short list for my first computer. I was looking for good color graphics and wasn't finding many systems that were acceptable in that regard. The Rainbow was a bit out of my price range, but that didn't keep me from wanting one. My wife's professor had just bought one and she offered to take me to his cabin in the woods where I could meet him and check out the new computer. It was indeed a 100+ like this newer one you have and I was given a nice demonstration that just whetted my appetite. Still too expensive. Six months later I got an Atari 800 Home Computer System on closeout so I could actually purchase it. This was originally designed to be the upgrade for the 2600 Game System but then they decided to put a keyboard on it as well as a sophisticated modular operating system. This was all I really wanted. I learned everything I ever needed to know about computer science on that Atari.

[@WilliamHostman]

A number of machines had processor splitout boards for 8088+8087 and 8086+8087. They move the CPU onto the daughter card, and split the pinout. The threads I've seen either require login to view photos, or have dumped the attachments. Still, it's an avenue to examine. Like many others, I enjoy watching your weekly tech struggles, attention to detail, and seeing old machines brought back to life. New variant of old Dad Joke for you: Did you know Eve was the first computer user? She had an Adam and an Apple. (Original A&E were first users - Eve had an apple, Adam had a wang.)

[@Troppa17]

Yeah, it seems there is a daughter card that goes between the board and the RAM extension and will directly connect via an wiring harness to the 8088 and its socket below. And that might be the reason for the plastic sheet on that revision of the memory card.

[@rubyvolt]

my middle/high school had a DEC PDP11/43 with 40-50 terminals all over school. Some of the printer stand ones but mostly VT100s. There was a lab of 20 or so of those and a Tektronics graphics terminal as well. I spent most of my free time and some classes in that lab for 5 years.

[@davidpatton3180]

Having worked for Rockwell Collins/Telecommunications/Electronic Commerce, we used Dec PDP 11-35/34/44/24/84 processors as part of the Galaxy Automatic Call Distributor systems that fortune 500 companies used for their customer service call centers back in the 1970s and 1980s. The 11-44 was a fantastic processor that was extremely reliable and versatile, as Rockwell designed several cards for the UNIBUS to work with our systems. I still have a copy of my old PDP-11 programming card and my PDP-11/04/34/34A, PDP 11-44 and PDP 11-24 Maintenance Cards. This channel brings back a lot of memories from those days and many thanks for keeping these vintage systems alive and working. We also had Wang computers that interfaced with the Galaxy that fed it phone numbers to auto dial when telemarking was in its infancy. Well done!

[@roadsiderebels3039]

have it communicate with the outside world in some way. A BBS would be very cool!

[@CATech1138]

named Hellorld

[@christo930]

I am just the kind of geek who would call in. I still have a hard wired house phone and a 56k modem.

[@rlzr.]

Hi! It wouldn't be a complete Sunday without your video to watch. Your joy, when you get things to work makes me smile and cheer with you :) So you're asking what to do with the 11/83... Maybe this little shy machine could become something like a network controller? It would be adventurous, even epic, if you get it to proxy communication between Centurion, 11/44, maybe also the Rainbow? Just imagine - You send a document from Centurion via PDP-11 to DEC Rainbow and get it printed on LA50 - oh that would be legendary flex :D Greetings from Poland!

[@stephenchoiniere2530]

I worked for DEC at their semiconductor facility in Hudson, MA from 1979 - 1998 when Intel bought the semiconductor division. I continued to work there for Intel until they closed the facility in 2015. We made logic from LSI-11 stuff through Alpha AXP chips, StrongArm processor, then Intel P860, P861 and Bridge chipsets The group I work in had a couple of Rainbow systems. I had a MicroVax system in my office. DEC was a great company to work for. 😊

[@mudi2000a]

Nice! I loved the Alpha processor, those machines were SO fast. I worked at the computer center in a German university from 1996 as a part time during studying and we had so much DEC hardware, not only computers but also networking equipment. All worked very well! We had 4x Sabre and 2x TurboLaser , the latter was equipped with multiple gigabytes of RAM which I found enormous at the time. So many memories! Fortunately AMD later took over the team that worked on the Alpha and it created the x86_64 architecture we are still using today.

[@MicheIIePucca]

These episodes make me miss the 80s soooooo much. Thank you!

[@der.Schtefan]

1) This thing has a more sophisticated pre-boot environment than some modern UEFIs 2) You know you are in trouble when you're getting a WRITE error while READING a disk :)

[@highpath4776]

yeah (2) what was happening there ?

[@russellhltn1396]

@@highpath4776 I can only guess that the program wanted to create some type of temp file.

[@der.Schtefan]

@@russellhltn1396 I think the drive just threw random errors, since a temp file would be a write error when writing

[@geepeerces]

@@der.Schtefan FWIW, floppy drives didn't really throw any errors, its the controller card that decodes the sectors that would throw errors. The floppy drive itself just had serial serial raw data in, serial raw data out, write enable, and step in and out for seeking, and a few control and status lines like spin up. Even the data formatter that took FM or MFM pulses and turned those into 1's and 0's was in the controller.

[@bobdinitto]

Great job rebuilding the DEC Rainbow! I wrote the datalink layer for the original Rainbow's DECNET protocol stack, so for about six months I used a Rainbow as my daily driver. Mine wasn't a fancy Rainbow like this one though, just the basic model with a hard drive. At the same time I also had an IBM PC-XT on my desk for testing.

[@emmanueleferrarotto2986]

If the hard drive controller card is much rarer then actual hard drive it might be feasable trying to reverse engeneer it to preserve the layout and have to possibility for replacement in case the original one fails one day. Great Video as always ^^

[@vinniemoscaritolo3318]

Consider getting decnet up on the 11/83 And see if you can get it on the existing network that’s out there

[@Richardincancale]

Lovely to see the 11/44 - look forward to seeing it run! I used one to build a system back in the 1980’s to enable older non-networked computers to talk to each other and the rest of the UK academic network (JANET). We hooked up ICL 1900, Honeywell 6680, IBM 360 plus links to newly emerging micro-computer systems. Using proprietary synchronous comms and X.25 on the backbone network. Lots of fun! My wife was jealous of the 11/44!

[@orionfl79]

Huh. I've never seen the insides of one of those before, but having tinkered around with the IBM and generic PC equivalents of that thing back in the day I gotta say that thing looks almost Cadillac grade on the inside!

[@danek_hren]

You are the only youtuber I know who is happy whenever he gets an error message and not garbage characters. 😊

[@rleeAZ]

The LA-50 is a re-badged serial C.Itoh prowriter.... parts interchange, they were solid workhorses.

[@lugiber]

Thanks for this! My dad used one of these in 83 (?). Without a color monitor. Used to program basic on it. Thanks for the trip down memory lane!

[@erniecamhan]

For the period, that is fantastically modular 👍🏴󠁧󠁢󠁳󠁣󠁴󠁿

[@goofyrulez7914]

It's amazing... what used to be a very high end machine is now barely adequate for serious work. And to think, this has all happened within my lifetime (I was TRS-80, Model 1, teenager and could only dream of a machine as powerful as the Dec Rainbow).

[@monad_tcp]

Also, that can be said about PDP11, and the most ironic thing is that people still use C , C was made to program those kind of machines. Modern machines are ridiculously different and basically run a virtual machine for C. When you have a MMU and a virtual memory system, you are in a virtual machine, C is NEVER baremetal unless on PDP11.

[@paulstubbs7678]

Same here, a TRS-80 M1 was my first box, I walked up to one in a shop, typed in what I read 'Print "Hi"' and it actually worked, I was hooked. I still have it, it's right next to me, running as type this.

[@oliverer3]

​@@monad_tcpI'd still consider C rather bare metal on microcontrollers where it's still the main language used.

[@c1ph3rpunk]

I wrote someone’s review this year on my NABU using WordPerfect 4. It wasn’t bad, and that’s a real world workload so it’s not impossible.

[@c1ph3rpunk]

@@oliverer3yep, that’s the most modern comparison, it has far more direct access there.

[@YuTv1408]

Love this channel and how you design, build and program hardware. Most people just know how to semi_program and yet still lack a basic understanding of computer architecture. ❤

[@TheJensenInterceptor]

The 11/44 and 11/83 were our best computers, but were really fast and worked so well. I installed a dual 11/44 cluster in an Oil Company to monitor and track oil coming in the an offshore oilfield. Really only the best.

[@maskddingo1779]

Awe yeah. The sound of an st412. 🎶😍

[@JanBruunAndersen]

Re: The 11/83 - I am more of a software guy than a hardware guy, so I would try getting Unix up and running on the 11/83 and at least 1 modem (or a network card if you want to be fancy). Next, get it up and running as a Usenet node. I cannot be certain, but I hope there is still a working Usenet out there.

[@truckerallikatuk]

PDPs used to be everywhere, so much so that an early hacker book I have has tips on how to break into one (along with a slew of other same era machines).

[@neilthomas6042]

A funky looking machine, glad you got it working. Cute little bunny at the end, want to reach out and give it a cuddle❤😊

[@Zone1242]

Great video and very nostalgic for me - worked for DEC from '86 until 'the end'.

[@binarydinosaurs]

I think that's got to be the cleanest 'bow I've ever seen, aside from when they were new of course. We sold a lot of them back in the day, and I was very pleased when an old customer of mine visited in the late 90s and brought up not just a VT102 for me, but also the 'bow 100B I used to use as a terminal on their PDP11/23. It's not well at the moment, hopefully just a dry joint in the video circuitry. Excellent stuff as always!

[@SockyNoob]

John is badass for giving you a second Rainbow and the color monitor, holy crap! That Rainbow hopefully will see some action at places like VCF Southeast, right? The Rainbow's serviceability is honestly one of the best I've seen on any piece of electronics period.

[@mistermac56]

I never owned a DEC Rainbow, but I did own a Pentium 100 DEC PC that was manufactured by Tandy. It was a workhorse. I worked with DEC Alpha servers when I worked in IT for a community college from 1998 until I retired in 2012. We moved from the Alpha platform to Sun/Oracle SPARC servers in 2007 and Banner higher ed campus management software.

[@macgvrs]

That is definitely a unique machine. I had an 8080 based dos computer, until the motherboard went up in smoke. Don't recall what it had for drives but now I may need to look at what it has since I still have it. I remember all the settings you had to make to get those old drives to work. Not like more modern computers that auto-detect everything. I really enjoy seeing these old computers being brought back to life, especially when they are rare. Really looking forward to seeing the Bendix run again.

[@mikehigham23]

Ahh, lovely. Well I don't know about 'Using a PDP-11 to *DO Something*". We just programmed our 11/780 to be an account system for my employer. And later onto a VAX 11/780 & 750. But the machine the 11/70 replaced - a PDP-8, entered a new career, controlling the Runway Lighting at London Heathrow Airport! 50 years ago.(Maybe still there today👾😂). So, sure, DEC machines were versatile.

[@vinatron8075]

Awesome my dad worked on one of those at Cornell University. I'd like to get my hands on one to remember him talking about it.

[@Richardincancale]

The paper tape loops are used to tell the printer about the number of lines per page there are so the skip to top of page works. We used different loops for different paper, eg the green a white sheets for general print outs and special forms for stuff like payroll or accounting packages.

[@BarkEaterJ]

We heard there was a "regisdem", and there was a hint of white DIGITAL logo and green text, but haven't REALLY seen actual color...yet.

[@larryroyovitz7829]

Its so satisfying to plug a BNC in.

[@SergeiJonovich]

How about setting up the DEC PDP as a bowling alley controller.... ;) Plus you get to build a bowling alley to go with your pinball machines!

[@IainShepherd1]

Run original Therac-25 control software on it and scream when you press Enter! …too soon?

[@keyboard_g]

Time Correct OS throwdown for the PDP. TOPS10, TOPS20, Multix.

[@dherrendoerfer]

Most of the PDPs and VAXen were connected either connected to terminal multiplexers and a modem, or to other VAXen to cluster - Sometimes there was a tape drive, but most of them were just multiuser systems, database servers, or storefront servers.

[@SalvoMorina]

My first CPM/IBM-DOS machine in 1983...

[@jtsiomb]

The LK201 should have a microfuse on the power input which probably blew and should be fine when replaced. I just connected an LK201 to a VT320 backwards just 3 days ago, because I didn't have the correct cable, and had to do the exact same repair. As for the PDP, I would install 2.11 BSD UNIX on it. I'm not a huge fan of the rainbow as a terminal. It feels a bit overkill in place of a real VT-whatever. It's similar to how I'd feel if you used a PC running kermit as a terminal, but that's just me.

[@F4LDT-Alain]

Thank so much for this trip to my past as a former VAX/VMS sysadmin. I've had a top-spec'ed Rainbow as my main desktop machine for many years when I was administering clusters of VAX-785, then VAX-8700 then MicroVAX 3400/4000. I loved it. It's extremely well engineered and reliable, it had the absolutely perfect VT2xx emulation I needed for my work, including the famous REGIS emulation of the VT240. It had a better and more advanced design than the IBM PC. It was only replaced by a VAXstation 3100 in the mid-90s. I would have loved to see the REGIS demo... maybe you can find another source for it.

[@bradnelson3595]

I remember that old song, "Winchester Controller." Great song.

[@TheJensenInterceptor]

When I was DEC engineer we always observed grounding policy and bags and bubble wrap specially designed to put the boards on. As you know CMOS is very fragile and easily blown. So laying out on the desk is asking for trouble. You need to follow correct anti static policy with an anti static mats. I followed anti static procedures until 1990 at least.

[@a_funyun]

Perfect for my workday this morning! Can't wait to watch

[@fotoralf]

Thanks for this great trip down memory lane. I had a VT180 (VT100 plus CP/M board and double disk drive) before I got the Rainbow 100 with everything you've got there minus the hard drive which was 7000 deutschmarks for the 5 MB and 12000 deutschmarks for the 10 MB. Plus I had the upright floor stand for the Rainbow. Eventually, it was replaced by a Amiga 2000. Those were the days... :-)

[@soundguydon]

I love your videos -- been watching your channel for quite some time now.. This system is very interesting & honestly I miss the sound of HDs and FDs whirring and doing what they did. My first HD was a 20 Meg full-height 5 1/4" monster that literally shook my cheap desk whenever it was seeking lol. I really miss those days & your vids take me back!

[@ronny332]

The first Computer I ever touched 🙂 My dad worked for DEC back in the day and did all his work reports on that machine and transferred it by modem (in Germany we called it Acoustic Connector at that time) to his HQ. Awesome memories. But his screen was amber, I think. Should be all still be in his basement, hopefully.

[@karlbauer4616]

der Keller hört sich interessant an...

[@ronny332]

@karlbauer4616 in jedem Fall. Mein Vater hat von 1976/77 bis "zum Ende" (HP Übernahme) bei DEC(/Compaq) gearbeitet, als Techniker im Außendienst. Ich habe als Kind auf den Schaltern einer PDP-8 Raumschiff Enterprise gespielt. Das Teil steht immernoch wie es damals da. VTs, Platten, Rainbow, LA Printer, Robin, sollte alles da sein. Auch eine riesige Festplatte hat er noch stehen, mit 2 Personen unmöglich zu heben. Neueres habe ich teilweise hier, Venturis, eine Alpha. Ich denke der Tag wird (leider!) kommen, wo ich über die ganzen Schätze herrschen werde 😕

[@karlbauer4616]

@@ronny332 ich hab 1979 in böblingen auf einer ibm/360 angefangen cobol usw.zu lernen, hatte mal ne ibm/32 zuhause, jetzt nur noch pcs... ich weine meinem tandy model 1 und model 2 nach...

[@ronny332]

@@karlbauer4616 als BJ 1978 kann ich da nicht mitreden 🙂mein interesse an den ersten versuchen im home bereich ist in jedem fall da, aber ansonsten besagte Rechner meines Vaters, oder selber mit 8 Jahren einen Schneider PC, oder C64 und Amiga 500 bei Freunden.

[@dysfunctionalwombat]

I'm really enjoying the DEC Rainbow content. It's a system I still want but I'm glad to now have a lot of my questions about it answered. Perhaps on the PDP you could run AT&T System V, I believe that runs on the PDP11

[@LeonDerczynski]

What a cable, that is ridiculous. Love it - very DEC!

[@ktheis1]

I remember seeing ads for the Rainbow in Byte magazines. I grew up using Prime and PDP minicomputers with dozens of users across multiple classrooms and offices and wondered what the big deal about a single user computer was. After using software written for CP/M long enough I really hoped the mini companies would adopt CP/M software for the minis. Pity it didn't work out that way. Good software, multiple users on one hardware platform would have been amazing. DEC could have ruled the world but the mindset just wasn't there.

[@JT-kz7kq]

I'd like to see a Calcomp 565 x-y plotter connected. We had one in the 1970's and I wrote assembler code for it. I can't remember which PDP controller card was used but it's memory addresses were 177452 and 177454 (octal) (I think!). Producing some hard-copy graphs and fancy writing would be truly epic!

[@TheJensenInterceptor]

11/83 were only really used for Word processing , although I did have a few out there installed in Nuclear power stations to monitor aspects of what goes on.

[@jazzathoth]

Pdp-11s were used for early cnc machines and industrial automation. You could find some old software for a cnc system and hook up a few stepper motors for a demo.

[@ttyR265]

I watched the original Ghostbusters for the first time in a long while and what did I see at about 20:54? What I think is a DEC Rainbow with monitor and printer! Annie Pott's character had one as the receptionist at the fire station.

[@Edward-k5u]

I had a DEC Rainbow 100 back in the day. I installed a Tandy Smartwatch to give it a real time clock and upgraded to DOS 3.x. It had monochrome graphics and a hard drive. It even had a flight simulator program! Compuserve had an active DEC forum. I don't know if that's archived anywhere.

[@timc3600]

Glad you didn't merge parts into one system. I was wondering if you needed to do a re-alignment on the floppies, but your cleaning seemed to work. Nice work IIRC, lotus commands started with a forward slash. A quick Google shows that the documentation is still available on-line

[@robynr447]

We used a PDP 11/34 (and then a small VAX compatible with the chassis) as a Printer Server and connection to a Super-Computer as a Card-Reader plus a workstation for remote Tektronix Graphics terminals. We also had the 9-track Tape drive in operational state.

[@johnmaxwell4941]

The stock Rainbow 100 does support the 8087 - I have one in one of my Rainbow boxes. There should be an empty socket near the 8088 on the mainboard. I had a copy of AutoCAD 8086 lying around somewhere, but I never tried to shoehorn it into the Rainbow. One point of interest, not sure if anybody below mentioned it, is that I keep the Rainbows around for formatting standard DSDD 5 1/4" diskettes for use in MicroPDPs, MicroVAXen and Pro300-series boxes. The Rainbow user community (ie. MSDOS users) would not tolerate buying specially-formatted floppy disks (at outrageous prices) so it was the only model which allowed the Western Digital controller to format diskettes! This function was lobotomized out of the Pro, MicroPDP and MicroVAX controllers IIRC. I suppose that disk utilities now are able to duplicate the format of RX50 diskettes in imaging, but not too many 360K floppy drives around for true formatting/reproduction - but, YMMV. Cheers! (BTW, I keep a Tandy TRS-80 Model 2 around to format standard 8" DSDD diskettes into RX01-compatible formatting for my PDP-11/84 and PDP-8 machines, but that's a story for another time, I guess!)

[@joseph9770]

The Rainbow is like the ultimate nostalgia generator for me. They had one of these at a local university in the library and I was always drawn to it for some reason. Maybe it was because the best thing I had experience with at the time was my Apple][. :-o Very cool to see one of these running. I almost snagged one of these locally but we couldn't agree on a price. Only downside of this surge of interest in vintage computers is how high prices are getting on the more interesting machines...

[@RockyBergen]

Whenever you do a follow up, don't forget to show us this monitor display color! ;)

[@ernstoud]

The amount of chips on all those cards! Just bought a small mini PC (for EUR 79 !) and it has less than 10 chips, SSD included. Progress!

[@augustuscrocker9328]

Great job on the restorations! I would suggest using one of the PDP-11s as a communications/device controller for all of the computers in your lab. See if you can pass messages/data from the Centurion to something crazy like the Bendix machine. See if you can enable bisync or SNA/SDLC and communicate with an IBM mainframe or something. Maybe a time-sharing system? I have to believe there are lots of application software and utilities laying around for the PDP-11. As for using the color monitor, there must be a copy of Harvard Graphics somewhere !!

[@FordGT40MkIV]

The delay lines on the Winchester controller might be part of a digital data separator. I am familiar with one designed by an NEC engineer who worked on their uPD7261 HDC device. The discrete version based on 74 series TTL and two delay lines was incredibly reliable. He was working on an ASIC version as companion to the 7261 but I’m not sure if it ever became a product as the 7261 was withdrawn from the market.

[@uewepuep]

Yes, I'd just like to see the first unix running on your PDB-11.

[@thirdwheel1985au]

That monitor is nearly as old as me, also born in July 1985. Oh, hey, a grey hair...

[@tomasprybil5310]

Obviously you should network the PDP and connect it to HECNET. See you there !

[@crabdonkey6381]

I liked the Rainbow, but we had endless problems with disk interchange. There was something goofy about how it formatted disks. Once we put an IBM formatted disk in it, the disk would no longer read in a PC.

[@russellhltn1396]

I seem to recall some track width problems in the early days. You could format a disk in a 360K drive just fine, and a 1.2M would read it. But if the 1.2M wrote on it, because it had a narrower track, the 360K couldn't read it back as it was seeing both the original and re-written tracks.

[@davidduma7615]

Yeah this sounds familiar.

[@EdwinSteiner]

"Write fault error reading drive A" I see the venerable tradition of horrible error messages goes back well into the 80s.

[@rabidbigdog]

I worked for, and then with Digital for years, but always thought the Raindow was also a PDP11 inside. Ooops. Would love to have one.

[@markbanash921]

When I was in graduate school back in the 1980s, DEC threw one of these Into the deal when my advisor bought a microVAX. For some reason no one used it. I had the microVAX for serious number crunching and an IBM PC to do my data collection so I was all set.

[@Somelucky]

I think one of those fancy reel tape storage systems would look nice with the PDP.

[@highpath4776]

If you can use excel you can get the gist of 123 quickly. The /X commands in cells are a macro programming language, which is useful to learn. / finds the menus

[@alabamacajun7791]

Running 99.723839% perfect which close to 100 as you can get. One column of RAM cells stands in the way. Nice old stuff. I wonder if Visicalc was available for DEC.

[@highpath4776]

not sure , I guess Lotus borrowed some ideas for 123, The PDP (or VAX) should run FINMAR (FINancial MANagement)

[@larryk731]

I think for lotus you choose spreadsheet and the / brings up commands

[@DocBanner]

Yes, slash for menus

[@christo930]

There is a RAM utility you can work with that I used extensively back in the day. I think it originally came as a type in program in an early PC computer magazine. It's called UMASCAN It's on the internet it gives you a quick visual of the RAM. I used it into the mid 90s. It is excellent for anything from early dos till the end of DOS. It's great for seeing what you have to include in the emm386 (EXE) include statement for mapping RAM to the UMA. This might help you find the missing RAM here. BUT, I think the machine is behaving correctly. You really cannot go past the A segment even with an MDA card. The video bios is in the B segment and the winchester is in the C segment. Given all the colors of this machine, it likely has the entire B segment filled with RAM. This would give you a continuous 704k. The first 10 are conventional memory and the 11th being the A segment.

[@horusfalcon]

I don't have a clue what you could do with that 11/83, but I've seen some great ideas here. Hope you find something that trips your trigger.

[@old-schematic]

Throw it in the dumpster. Useless tech and has no value anymore, unlike tubes for example, which you still could make sweet sounding amps with

[@RommudohDev]

"Percussive Maintenance" - nice!

[@lmantuano6986]

one of our tasks in Field Service was to perform PMs. Preventive Maintenace.. occasionally they turned into Provocative Maintenance episodes.. done that, been there..

[@dschultz9466]

23:26 TRW chips, I forgot they made components. 'Tomorrow is taking shape, at a company called TRW'

[@timballam3675]

Put the 1183 on the web so people can use it?

[@a_funyun]

What about pairing the 83 with something like a MicroVAX II or a DECstation of some kind like you mightve seen at university back in the 80s?

[@ran2wild370]

1st-ly it looks like guys back in late 70s and early messy 80s didn't feel much lonely with IT stuff. Apparently quite enough processing power was available for all kind of enterprises. Not much convenient 80x24 text mode user interface, but they managed to cope with that.

[@jimbass1664]

Use the PDP to control a 3d printer? Or robot arm. Robot arms are always fun.

[@subynut]

A system with both an 8088 AND a Z80 CPU?!? That's really cool!

[@dbradley65]

From what I remember of installing 8087's on IBM PC's they were an obvious empty socket you'd plug the chip into. I think similar in size to the CPU. I'd expect the same of the Rainbow. Since there doesn't appear to be any empty sockets, I'd guess the mother board wasn't built to provide one. And I'm sure if there was one plugged in it would be easily recognizable. I just remember nervously pushing those chips into the motherboard socket and praying I didn't bend a pin. They were pretty easy, but it was just the thought of blowing a few hundred bucks by a simple screw up.

[@aleksandarsusnjar9574]

Depending on vertical clearance and whether 8088 is socketed, a daughterboard with both 8088 and 8087 can be inserted in the 8088 socket.

[@colint]

@@aleksandarsusnjar9574 You are correct. In fact it's only 1 pin that is different so some people would piggy back the two chips with just the P_Sel line wired differently.

[@crabdonkey6381]

The 703 KB may be the "real" memory. Remember IBM-PC only "sees" 640 KB, Any additional can be used as a RAM drive. Later Expanded and Extended memory were introduced, but I never remember it being used on a Rainbow.

[@egelmuis]

An 8086 has 1024 kb of address space. The bottom 640 kb was reserved for RAM. Directly above that was a chunk reserved for hardware extensions, such as graphics cards and the ROM, but that doesn't take up the full 384 kb. On IBM PCs and close compatibles, that remaining space was wasted, on some other partially IBM compatible machines, the remaining part of the address space was used for another piece of RAM. DOS and some progammes, such as Lotus 123, could just use that. So in the case of the DEC Rainbow, that was 63kb.

[@aleksandarsusnjar9574]

Yee, 640kB was reserved but more contiguous memory could be made available if nothing else is in the way. With later CPUs expanded and/or extended memory could be remapped to that area. Remainder was either paged ("expanded") or could only be used with later CPUs ("extend" memory beyond the first 1M).

[@estebanvillalobos2303]

great video, chuckles. very interesting.

[@geepeerces]

I'm pretty sure MSDOS 2.1 would not be able to read a CP/M diskette as they used totally different file systems, where MSDOS was FAT based, while CP/M was FCB based. There were utilities that could read CP/M files and transfer to/from a MSDOS disk.

[@RonJohn63]

6:07 A hard drive assembled in the USA. 20:15 704 is 3x64 smaller than 896. Maybe the RAM board is fully populated, but with _smaller_ chips? 23:14 That blanket statement is *just not true.* Plenty of businesses uses PDP-11 to run business software.

[@McTroyd]

It would be lost on anyone used to a PC made in the last couple decades. But, PCs with sophisticated on-board firmware, capable of detecting hardware and showing on-screen options, even running as a free-standing terminal, were NOT common in that era. DEC was really flexing the engineering chops with the Rainbow there. Could not have been a cheap machine, especially with those hardware options! As for the 11/83, maybe connect it to an IRC chat room for the scrolling display in the background? Or some other recording set demo?

[@lumpytapioca5062]

The awesome thing to hook to the PDP is the Internet.

[@SteveHazel]

holy crap a dec rainbow - my computer science lab at Seattle Pacific Univerity had those circa 1986. I had no idea they could run cp/m or be a terminal. not that i'd want em to - I had turbo pascal !! We had those same printers, too. But not a hard drive - that's far too luxurious. I spent a couple years on em before we went to higher spec ms/dos machines with an EGA babyyy. But my commodore 64 at home was my main squeeze. Until I bought an Amiga 500 which was THE best computer I've ever had. Up until Commodore died sigh. I tried a mac classic after that - BLEH. didn't like ms/dos anymore after windows at work (circa 89). But win95/8 - noice. Now Kubuntu is my fave. Qt and c++ on Kubuntu - da best.

[@davidduma7615]

I had Turbo Pascal running on my Rainbow 100+ in 1984. And Lotus 1A. That machine was a major advantage in getting me thru grad school.

[@erigobelli]

My MS-DOS memories from the university are telling me that the 8087 is a math (floating point) co-processor. Used to speed-up mathematic operations.

[@meltdown03]

Get DecNet running on both the PDP's