The Most Important Computer You Don't Know About

[@cruftist]

I remember when I bought my first microcomputer. The local dealer sold the Apple 1 and the SOL-20. I bought a SOL kit and soldered it together myself. I recently finished restoring everything to working order. We should talk.

[@cygil1]

How does it feel to know if you'd bought an Apple 1, you could get six figures for it now!

[@squirlmy]

@@cygil1 The majority of Apple 1s were disposed of and forgotten. Chances are, if he bought an Apple 1, he would have trashed it, sold it or given it away. Feeling bad about that outweighs never getting it in the first place! It's kinda twisted for you even to suggest that, after he did something so amazing as restoring his SOL!

[@Austin-gj7zj]

@@cygil1party foul man, what the hell is that

[@danilko1]

@@squirlmy Not siding with anyone... By keeping and restoring his SOL-20, @cruftist sounds like an upstanding guy and would have still owned the Apple 1, if he did buy one... The thing is, woulda coulda shoulda... I think it's still exciting to have been close enough to touch or buy one, in the first place... At the time the SOL was a better buy,... I would have bought that instead of the Apple 1...

[@johncoenraads9681]

Not only have I heard of it, I put one together from a kit purchased at the First Canadian Computer Store, which was exactly that. Went on to hook it up to a 10 rank pipe organ thus turning it into a player organ. Also wrote software, all in 8080 assembler, that let me easily enter the musical score even of complex music I could not play. A Bach toccata fitted nicely in 32 kilobytes of memory. Thanks for stirring up some happy memories. Now I'm building Virtual Pipe Organs using Arduinos. It has been quite a ride.

[@michaelbauers8800]

I was intrigued by some of the open platform Raspberry PI or Arduino synthesizer gizmos. But I guess I am too lazy to sit down and master the skills needed to code up what I really wanted...something like granular synthesis.

[@Hamboarding]

Wow, that sounds interesting!

[@SPINNINGMYWHEELS777]

what was the interface beteween the CPU to the organ.. ?? Since this was pre-midi..how did you trigger mechanical ie. keys ect of the Pipe organ?? What year was this ?? what is the name of this computer store you mention.. Canadian Computers first opened in Kingston but there were other places to buy computers and kits.. like Radio Shack comes to mind... One final question.. where was this organ located? I would like some of these details if you dont mind adding - any photos ect of the process and remnants of the code you used?

[@johncoenraads9681]

@@SPINNINGMYWHEELS777 1. Custom designed board occupying two large sheets of VeroBoard. Communication via computer's serial port and UART 2. Organ was electro-pneumatic with custom Multiplexed Switching System. Transistor switches "operated" the keys 3. Early 1970s 4. First Canadian Computer Store in Toronto 5. Organ located in my house in Kingston 6. Code remnants on cassette tape: scattered to the winds.

[@johncoenraads9681]

I'd send you a link but KZbin doesn't allow that. I'm active on the Organ Forum.

[@Charlesb88]

An interesting fact about the Sol-20 was that one of the key guys behind it, Les Solomon, was the editor of Popular Electronics magazine and one of the key backers of a tape data storage standard known as the “Kansas City Standard”. For those that don’t know, back in the early to mid 1970’s the cheapest way to store data permanently was paper tape (aka punch tape) where data was recorded on the tape as punched holes that could be read back by a paper tape reader but it was prone to jamming, tearing, and others issues, and many early hobbyist computer users wanted a more reliable method for storing data. Sol was one of several who had the idea of storing data on a compact audio cassette in the form of two tones to represent ones and zeros, as replacement for paper tape. One problem was that early hobbyist computers all adopted their own incomparable proprietary methods of storage data (as audio) on cassettes. So he and someone from Byte Magazine got together and arrange a meeting/symposium with other early hobbyist computer companies to devise a standard for data storage on audio cassette which became known as the “Kansas City Standard” due to the symposium taking place in Kansas City. Unfortunately, while some computer manufacturers did adopt this standard, many others did not such Commodore, Apple, Sinclair, Atari, and Amstrad, and went proprietary instead. Part of the problem may have been that this standard wasn’t the most efficient method for storing data on tape (as audio) and thus these other microcomputer companies preferred to develop there own more efficient standard, plus there was the added benefit of locking in their users to each company’s own platform.

[@Charlesb88]

@Jeff Desert Mountains Paper Punch tape was different then punch cards. It was a basically a long strip on tape sort of like paper version on magnetic tape but with holes used to Indicate binary digits. Punch cards where produced in a stack where you had to carefully keep them in the correct order. Then you put them in the punch card holder on the punch card reader and the device would pull one card after another to read the data off them, shooting them to a second receptacle. The way the data was stored on punch cards and paper Punch tape was similar though. You can see videos on YT showing how each worked such as on the Computerphile chanell from the University of Nottingham.

[@njphilwt]

@Charles Bunnell.. Cool story. My friend had one of these in 1977. His same was Solomon. No relation. In those days we were more interested in having a terminal to get into our school time sharing minicomputer by modem, so the name terminal computer made sense to us. I’m not sure which OS it had, but it had some very impressive games.

[@firesurfer]

Pop Electronics is where the infamous Altair 8800 was featured on the cover Jan 1975. You can get the pdf. Many people consider it the birth of personal computers. In the 80s I did work for a factory that used paper tape to run automated punch press machines. The noise was deafening. I hated going to the shop to pick up material. I still hear it...KA_CHUNK. I had no idea it was Ziff-Davis that produced Pop Electronics. ZD was responsible for The Screen Savers and Call for Help. Leo Laporte is doing This Week in Tech (TWIT) now.

[@firesurfer]

@Jeff Desert Mountains It resembled a ticker tape machine.

[@Charlesb88]

@@firesurfer I am familiar with the Altair 8800 Popular Electronics cover. A lot of early hobbyist PC’s where announced via electronics publications, sometimes created with the help of people at the magazine as with the Sol-20. While the Altair 8800 was certainly in many ways a personal computer in a sense it wasn’t quit a mainstream personal computer the way the later Apple II, TRS-80, and Commodore Pet where (know as the holy trinity of PC’s) personal computers. These early PC’s where what i’d call a hobbyist computer as they required a lot of assembly and specialized knowledge to get the working and such. The modern Raspberry Pi other single board computers is the modern version the hobbyist computer. Back then It wasn’t until the holy trinity of PC’s I mentioned above came out in 1977 that you could buy a PC that could relatively easily be used by laypeople. The Sol-20 came closer to being a more ready to use PC then the keyboard-less Altair 2200 (at least in its default configuration) but it still wasn’t as user friendly as later PC’s.

[@CasualSpud]

Clint from LGR would be drooling over the woodwork 👍

[@SimonQuigley]

I think he prefers fake wood grain :-)

[@TheDiveO]

@@SimonQuigley made with the period-correct sharpies.

[@HrLBolle]

@@SimonQuigley no for his IBM industrial rack mounted behemoth he commissioned a real wood rack-box

[@seanwieland9763]

Just like 1970s synthesizers. 🤤

[@vjcodec]

The Apple-1 might make him drool a little more ahah

[@PebblesChan]

FYI The 909090… pattern is caused by the CPU executing a recursive 0xFF RST #38 opcode. This happens when the data bus has pull up resistors and nominated memory is not presenting data on the data bus. What’s happening is the CPU reads a 0xFF opcode causes the CPU to execute the code at %0038 which is also another %FF which gets it to run another %FF opcode. As a part of this process the stack pointer is being decremented by 2 with the return address being %0039 (%0038 + 1) being written. After being run so many times the stack pointer contains the video memory address hence displays the %00 %39 characters. To fix your boot problem check out the POJ (Power on Jump) circuit to ensure that the starting signal sequence is correct along with the first memory access is successful.

[@lucasRem-ku6eb]

Why you cry ASCII now, how mad are you ? memory space on Telecaster terminals ??? Why you went all mad here ??????

[@tommytron2000]

Where did I just no clip to here. These comments are crazy

[@lucasRem-ku6eb]

@@tommytron2000 who needs 1970 trash ? Normal people ?

[@PhenomRom]

How do you know this lol

[@UsagiElectric]

Painted blue steel and genuine wood? I feel like I've found my long lost brother! Excellent score fam! This thing is seriously awesome though. Both a gorgeous machine and surprisingly capable for how early it was. As for the "Local" key, my guess is that that is going to be useful when it's in terminal mode. My ADDS terminals have the same functionality. It essentially allows you to shift the terminal into handling things locally without sending or receiving any serial data. For example, if my screen is particularly full of questionable decisions and I want to clear it before flipping the camera on, I can hit "Ctrl + Local" to pop into local mode, and then hit "Ctrl + Erase" to clear the screen without sending any keycodes, and the "Ctrl + Local" again to get back to regular serial terminal operation.

[@Bobbias]

Guess I shouldn't be surprised to see you here.

[@michael1234252]

Also another Terminal computer as well that will go well with your Centurion.

[@applesushi]

Make it act as a terminal for the Centurion!

[@GordieGii]

I imagine this would be for 'local echo' where the screen shows the characters as they are sent out, because some remote computers didn't echo the characters that were sent to them.

[@voidstar1337]

Absolutely these are special, glad it has found you! They showed what a kitted-out Altair could become. The Sol-20 is predated by the Wang 2200, Q1, Sphere-1, Datapoint 2200 (all over $5k new in base form) - but still, the Sol-20 was a huge step towards that idea of an actual affordable personal computer with a bus and is about the earliest can-still-power-it-on microcomputer system one can find. We can find late model Wang and Datapoints, but pre-1975 stuff like Mark-8's and early Wang get substantially harder to find in willing-to-power-on working order (the components to make smaller switching power supplies evolved greatly sometime around '72, iirc).

[@douro20]

The Wang 2200 is a very interesting machine. It was the first in a long line of Wang computers which ran BASIC code natively- that is, the language was implemented in the CPU microcode. It also could do timesharing.

[@douro20]

Your last comment was deleted for some reason, but to answer your question the 2200 was a completely different machine, first introduced in 1973 and having several different implementations of the CPU, having either one or two 74181 bit-slice ALUs. The first machines had a separate compact chassis which contained the logic backplane but later desktop machines were all-in-one units. They were available with or without tape drive storage.

[@Mike_Neukam]

Check the reset circuit for proper operation, and try manually asserting the reset signal through a resistor to see if that will make it boot properly. Check all the address and data lines with an oscilloscope for any seemingly stuck bits. Also check that you have all of the proper clock signals present and timed correctly. I know that the early Altairs had issues with clock reliability, and the 8080 is a bit finicky when it comes to timing, but I have no experience with the SOL. Having that S100 connector right at the top of the expansion bus should make the issue relatively easy to troubleshoot.

[@DbugII]

Reset circuit is also what came to mind (it's a notorious problem on the Oric's 6502 for example), but then would he has this 9No displayed if it's displayed by the CPU?

[@andygozzo72]

thats what i was gonna say, maybe not long enough reset,

[@Mike_Neukam]

@@DbugII I assume the pattern displayed on screen is the uninitialized state of the video ram, but I'm not sure about that

[@kevinison5539]

On somthing this age I expect the capacitors have dried out. Check the reset circuit caps and also the PSU. The bottom line is all the voltages must have stabilised and the clocks up and running before the reset is removed. The PSU is of linear design judging by the size of the big cap, so check the supplies are correct voltage and also for ripple. Best of luck.

[@jeffreyhall5307]

Our high school electronics class made one of these! Thought ours actually said Processor Technology

[@Peter_S_]

There's a really good chance that keyboard auto-repeat mod was the circuit from Don Lancaster's CMOS Cookbook which was one of a handful of hack circuits and the end of each chapter called 'A CMOS Cameo'. It worked by intercepting the keyboard strobe line and adding a low frequency oscillator which started running if the strobe line was active for long enough.

[@idgamingfederation202]

my dad had one of these, I tinkered with it a bit but was rather young in the mid 80's and it was not in the best condition. he used to talk about training on a UNIVAC 9700 when he went into the Navy

[@ypoora1]

It's really interesting to see this. It's like a classic S100 computer in every way other than having the CPU, memory and terminal integrated. I suppose like an early motherboard!

[@rmcdudmk212]

I knew a guy who's dad had an Altair when I was in grade school. These old computers are chunky and funky. Thanks for sharing Action Retro. 👍

[@EmergencyChannel]

Fucky lol

[@rmcdudmk212]

@@EmergencyChannel oops didn't realize autocorrect dropped the n from funky 🤣

[@lucasRem-ku6eb]

Altair is good, the Blue machines ! We used them too, the terminal of the altair was not that advanced.

[@xsleep1]

Most excellent. Never knew this existed. Wikipedia says Felsenstein shard a garage with someone who was building digital clocks in a fine wood case; hence the amazing walnut on this thing.

[@lasskinn474]

There were companies in 70s that made cases in this style, companies or hobbyists bought them and built their own stuff inside

[@trs80model14]

I’d heard that they had gotten an incredible deal on the walnut wood and that’s why they made the sides from walnut.

[@lucasRem-ku6eb]

France people did used them, Telecasters, the pre internet terminals.. US people never used them......Waiting for Windows, text based terminal was not for the US people !

[@squirlmy]

@@lucasRem-ku6eb watch "WarGames"(1983) It shows both that some people did use pre-internet micros, and, more importantly why Americans were afraid to use them!!! lol srsly, the DEC Video Terminals were so widely used, they are still a software standard in Linux distros.

[@shmehfleh3115]

I used to own a Heathkit H-89 computer that could be considered a spiritual successor to this thing. It sported the ability to act as both a computer and a dumb terminal, and could switch between the two modes by pressing a key on the keyboard. Like that Sol 20, it sported a dedicated repeat key instead of just repeating after a second or two delay. It had a shift lock rather than a caps lock, which was basically a mechanically latching shift key. It also used a bank of DIP switches to set various options, like video mode, cursor behavior, etc. And I'm pretty sure it used the S-100 bus as well. It definitely predated the IBM PC and the ISA bus standard.

[@markbaker3238]

Also available as the Zenith Z89, its claim to fame was two Z80s, one for processing and one for I/O. I recall programming in UCSD Pascal locally and using it for a terminal to I think a Unisys 1100.

[@mikeking7470]

I had a Heathkit H-8 with the H-9 video terminal (horrible keyboard). Bought it when it was very old in kit years, replace one LED display and soldered a few wires (with the mandatory blister) and then would load a cassette then entered patches in Octal via the keypad on the front, patched the program and output it to a second tape. ext bot was perfect. Benton Harbor Basic baby! That was my first.

[@chironbramberger]

Thanks for all the great videos! Okay so if it were me, I’d look at the reset signal. If it’s only turning on and working properly like 10% or 25% of the time, then maybe the reset circuit isn’t working properly. Maybe it’s timing is off and sometimes it happens to reset everything the right amount of time but most of the time it doesn’t. Another thing is that if the power supply isn’t putting out the right voltage, or if it can’t sustain all the current the machine needs all at once when it’s powered up, then that might affect the reset circuit, which is often a 555 based timer circuit. However, overall those chips are very oxidized, so a careful cleaning of all the chips and sockets might be a good ideal regardless. If it is a reset circuit problem, then maybe a flakey socket connection due to oxidation is messing with the period of time the reset circuit is holding the system in reset, and cleaning the connections here would allow the circuits timing to work as intended. Then again with a system this old the capacitors might be bad and the whole system is electrically super noisy and having new capacitors would help. Without poking around with an oscilloscope and schematic diagram it’s hard to say. But those are my guesses off the top of my head!

[@grimmpickins2559]

I came to Action Retro for the retro-Mac shenanigans, I stay for the absolutely deep dives into retro computing. You, sir, are a hero. Thanks.

[@greatquux]

You’ve upped your game on this one! Absolutely awesome you got a reply from one of the inventors too! As far as only booting every 5 times, could be capacitors are old and need to “warm up” before working, just replacing them if possible might help?

[@bhangg_high]

As a child from the 90's, you had me hooked at "Hi. I'm NOT Troy Mclure". Liked and subscribed.

[@startedtech]

Amazing how simple and integrated this is compared to other S100 computers. I have a DIY home-built S100 system I picked up at an estate sale alongside an IMSAI, I'll have to study electronics a while longer and learn power supplies before I dare do anything with it, in the DIY'd linear PSU it's got five of the soup can capacitors. Not to mention the mystery hand made wire-wrapped expansion cards in it.

[@Bobbias]

Oh damn, sounds like some fun reverse engineering is ahead of you :)

[@surferdudemi]

IIRC there are 4 power rails: +/-5v and +/-12v. Some chips and interfaces required the negative voltages

[@squirlmy]

@@surferdudemi ? that was a standard for early PCs, but I'm not sure it applies to a DIY homebrew system.

[@surferdudemi]

@@squirlmy If it followed the standard. Some chips back then required -5, and true RS232 needs -5 or -12.

[@stevejackson8060]

Not sure if you noticed, and this could be caused by KZbin compression. But when you pulled out the personality module it looked like the first contact point was seriously corroded/scratched. Assuming this is the case and not some video glitch - as the OS is loaded from there might this not be the cause of the dodgy loading?

[@James_T_Quirk]

Oh, I like to see people fixing Old Computers, Nice to see Replacement parts for the Sol20 keyboard, P.S. When Cleaning Chip Pins, (Which I usually find is Number 1 thing causing issues), I Use a Pencil Rubber, just to get Tarnish off..

[@EveGantian]

I'd check the initial reset signal which probably should happen at switch on (likely using a capacitor, which may well have aged too much??) Just a thought, and a great video!

[@chrisguli2865]

Yeah that brings back high school memories (1977) - a fellow classmate built his own Altair 8800 system from the original MITS kit, then soon after got a SOL terminal to write BASIC and ASSEMBLY code by typing it in instead of having to toggle all those switches on the Altair. I recall seeing ads in Pop Electronics for the SOL, but all this nice 8 bit hardware at the time was out of reach for me as a kid going to public school on a limited allowance. Of course now I have a renewed internest in all of these classic 8/16 bit computers. It's amazing this SOL boots at all given that EPROMS have limited life span for data retention - perhaps that is a burned fuse type PROM. Those capacitors are HUGE because at the time all PSUs were the linear type and had to filter out 60/120 Hz to provide a nearly ripple free +5V. Later switching supplies used a higher frequency for smaller capacitors. BTW it's amazing those capacitors still work after 47 years, if those are the originals. I wish modern ATX PCs would be built like that instead of the tower config.

[@RichardFreeberg]

I still have an original Processor Technology SOL In my storeroom that's been there for at least 34 years. I purchased it for $600 dollars at a swap meet in Sunnyvale in 1980 and used it for several years to learn 8080A assembly language. That was the same swap meet where I almost bought the original Intel 4004 prototype board for $5 from a retired Intel engineer who was cleaning out his garage - but didn't because I was broke after buying the SOL. The next swap I attended the very same engineer was there selling more interesting electronic "stuff", but the board was framed, on display, and was no longer for sale! That 4004 board was the arguably the beginnings of the microprocessor revolution. Wonder where it is now? Thanks for the great video! Especially the part on repairing the keyboard and a source for the foam pads. SUBSCRIBED!

[@barrycole7403]

I never tried a Sol-20, but built my own S100 machine using the Processor Tech VDM1 video card in 1977. I use a separate Z80 based card from SD Sales. When I saw the pattern of Nul and 9, I instantly knew that the RAM at location x0038 was not being addressed. This was either a missing or non-functional RAM card, or the RAM that was shadowed by the boot ROM, was not reenabled! I used a better keyboard with Cherry mechanical switches. The hard part was making my own ROM with a hex debug monitor and later boots into CP/M and UCSD Pascal. Barry.

[@_P_M_]

I remember the full page ads for these in Byte Magazine, paired with (I think) the Helios II (?). I was just a young kid intercepting my dad's magazines. I was fascinated by this stuff. It just looked like the dawning of the future to me. It is so cool to finally see a real one turned on and running. Absolutely gorgeous case. My Dad ran the data processing center for a local bank and so once in a while he'd take me in to see the IBM mainframe. It was like being on the bridge of the Enterprise. All of the machines were bigger than me.

[@freddjie3097]

They housed a Sol-20 at the Living Computer Museum in Washington. There’s a photo of Gordon French, the co-founder of the Homebrew Computer Club seated beside one

[@Jordan4Ibanez]

That thing is absolutely incredible. Excellent work getting it to it's current spec. A little more finesse and you will have the ultimate 70s pc workstation

[@steveduerr6367]

I remember when all this stuff was new. Started out by playing Zork 1 (may have been called Microsoft Adventure) on my friends IBM PC back in 1978 or 79 (don't remember exactly). Got an Atari 800 1983, went to an Apple ][e in 1986 an Amiga 500 in 88 followed by my Cyrix 386 SX 33 in 1994 with a whopping 30 meg HDD. Good times.

[@Mueller3D]

If you check out the Sol Systems Manual 1977, page 165 describes the reset circuit. It notes capacitor C15, which you'll find near the keyboard connector. You should check it. It also mentions that SW1-1 (front dip switch bank) serves as a manual reset switch. The manual is very thorough and describes the system operation in a very detailed way. On page 255, I was very amused at the suggestion to use a piece of spaghetti as insulation for a component lead.

[@lilbill6089]

Before heat shrink tubing there was spaghetti tubing. It too was hollow but didn't shrink. It's probably referencing that.

[@brianbresnahan9718]

Great video. I appreciate your courage to open this little beast up and fix the keyboard. Amazing that the personality/OS card is removable and burned into an EEPROM. Love your comparison to OS on an SSD card.

[@voidstar1337]

Would love to see CP/M running on this someday. But just finding a tape (or paper) loader will be one challenge, let alone a working disk controller and drive. But the fact one could obtain an actual disk operating system for a micro, I think that's one of the defining aspects of the Sol-20 - that the community started to realize the need for such a thing (memory and file management) and move past boot up BASIC calculator-like systems.

[@retrozmachine1189]

I built a kit computer in 1981 or maybe '82 as a learning exercise. It was Z80 based and had an S100 slot. The power supply I built for it was linear and used a similarly large transformer. From memory one of the windings was 18V 8A.

[@michaelbauers8800]

18V, now that's damn weird. I wonder why?

[@retrozmachine1189]

@@michaelbauers8800 18VAC had a centre tap and was used to provide unregulated DC for the +12V and - 5V regulators as well as unregulated + / - 16V for the S100 bus. Another winding provided unregulated for the +5V regulators and +8V unregulated for the S100 bus. I had to go look it up, turns out the articles can still be found at the internet archive site.

[@michaelbauers8800]

@@retrozmachine1189 Thanks. Certainly not a voltage I expected to see, but whom am I to second guess electrical engineers, when I barely understand electronics :)

[@DavidStahlOLDHAPPyMACs]

Great computer A Beast of a unite That foam pad thing on the older keyboards was a quick and dirty engenering cost savings back in the day great video sir

[@AtomicShrimp]

It's beautiful. I want one, immediately.

[@jeffnay6502]

I have a working SOL-20 Terminal Computer i my collection. I do believe it was way ahead of its time. I also think that Steve Jobs and Steve Wozniak may have copied it, when creating the Apple II using the 6502 processor, instead of the 8080 as the SOL-20 used. Built in Keyboard, serial and parallel port and video output. My favorite game to play on this machine was Target.

[@trs80model14]

Target was “adapted” for the TRS80 as Flying Saucers and was my first TRS80 arcade game

[@jeffnay6502]

@@trs80model14 I still have several TRS80 Model1's One I could use some help repairing.

[@toddmarshall7573]

This was the first computer I bought (I think about 1977.. ~ $5K). It came originally with 4K or dynamic ram ... that didn't work. I had to replace it with 4K of static ram ... which put out lots of heat. I also purchased the accompanying Helios dual 8" floppy drive. A single voice coil actuator positioned both disks simultaneously. It was the fastest drive available at the time. I particularly liked the PT-DOS operating system and preferred it over my later IBM-5051 with PC-DOS. Interestingly I later bought a DEC 1130 ($30K) and was surprised to find it wasn't "big enough" to run the programs I had written for the Sol. I had to rewrite them. I still have the machines (not including the DEC 1130 which I was glad to get rid of) but they're sure not in as pristine condition as the one in this video.

[@DeryckSchnee]

Very cool. Never seen this computer! Absolutely amazing that it's mostly functional after all these years. Excellent walkthrough/break fix. Thank you.

[@konnimusic]

a prebuilt compact computer with an operating system, expansion slots and many more advanced features from 1976? this machine must have been WAY ahead of its time.

[@andrewowens5653]

Thanks for the memories. I started in computers in 1976 at the age of 14. Got a job at The Byte Shop computer store in Englewood, CO. I really wanted one of the Sol computers, but they were out of my Moms budget. My first computer was a Mostek KIM-1 single board with a Hexadecimal keypad, 6502 CPU w/ 1KB static RAM. My second computer was Apple II serial number 000745. Got it the same week that the 16KB DRAM chips were released, so I could do "Color Graphics" !! Cheers!

[@thorerik]

If I where to guess, the local key would be to switch between entering locally and directly on a mainframe like a terminal, hence the name "Terminal computer"

[@jacquesmertens3369]

If I had a computer that was dying and could no longer be rescued, I might call it a terminal computer. It would make me very sad. What you are referring to is commonly known as a computer terminal. As to the key presses needed to switch from terminal mode to local mode: this is described in chapter VII of the 1977 or 1978 manual. The manual not only describes how to operate the SOL-20, but also how to build it. It's a fascinating read. Highly recommended.

[@MrJest2]

@@jacquesmertens3369 My first job out of the military had a terminal at my desk (hooked to a PDP... whatever; 10 or 11 most likely... running some flavor of Unix and ASK/MANMAN). I also had a roommate who was a software engineer, and he had a few old Wyse terminals hooked up to his high-tech at the time 286 machine, which we would use to BBS on. Gads, that seems both sooo long ago and yet only yesterday...

[@PhenomRom]

@@MrJest2I’d love to hear more

[@MrJest2]

@@PhenomRom Of what? It was certainly an exciting time, kind of at the starting years of "Silicon Valley 1.0"... which was very different than what goes on there today.

[@itsgruz]

Love the design and colors! That is a beautiful computer! 😍

[@danaeckel5523]

This is a cool video. I have seen the ads for these systems in Creative Computing and Byte magazines. Never saw one featured in a video.

[@RobertDeloyd]

Oh, I knew about it... I was drooling over the ads when the Sol first came out. Glad I found this channel... Subscribed and selected ALL 🤗

[@BrassicGamer]

There are schematics for an S-100 OPL2 sound card - that would be amazing to see! Also enjoyed how often you had to repeat the word 'repeat'. Looking forward to the next episode!

[@duncan94019]

In the mid 70s I was trying to come up with a deal with Processor Tech to sell their machines in Europe. Nothing came of it. But I did get a nice tour of their factory. I remember them commenting on how expensive the metal work was. The main impediment to paper tape was cost. It wasn't that bad to work with, although editing it was a pain. Earlier in the 70s I used paper tape for ALGOL programming of a Hybrid computer. And for the time, it was quite doable.

[@harryragland7840]

I remember seeing these listed in mail order catalogs. I believe that they were sold as Pecos-1 or that was their OS. I think they also had a proprietary programming language as standard. Our school district had a PDP/11-40 at that time so all of our computing was done at 300bps across an acoustical modem to an LA36 Dec Writer.

[@Oldbmwr100rs]

Back in the mid 70's a friend's father bought a sol 20 kit, and they built it together. He converted his sony portable B/W TV and had some solenoid kit that went inside an IBM selectric typewriter to make it a printer. He was the first person I knew with a computer. It probably saved the family money which was otherwise spent going to Lawrence hall of science in Berkley every week to use the computers there.

[@donferrie4070]

Was that dcf?

[@koset]

Guys, I really enjoyed this experience. I’m just old enough to remember seeing ads for this. I was only in middle school, so just a little too young to have bought one. I did get a TRS-80 in 1980. I always wondered about this. Thanks for sharing the experience.

[@rolfhelder7771]

Nice keyboard repair, but: fingerprints can blur the electrical contact of a contact surface. Remove every fingerprint from contact surfaces with proper cleaning stuff to prevent corrosion later on. Wearing nitrile gloves can protect these surfaces while working.

[@bf0189]

Didn't know this and I'm a big antique computer buff! Woah ! This is amazing. Also the LTT screwdriver is my favorite screwdriver. They need to go into the tool making business full time. It's actually incredible especially for their first shot

[@yacobgugsa2524]

I just wish Linus hadn't dug in his heels regarding the warranty. GamersNexus rightfully called him out on that.

[@narthted8200]

It did take them years to get just right, so I would expect no less.

[@3DMegadoodoo]

What am I missing here? It looks exactly like all the other bits-in-the-handle screwdrivers I've ever seen.

[@stevejackson8060]

@@3DMegadoodoo there is a video by Project Farm that goes into this. Basically the configuration of the ratchet gears, grip power of the magnetic tips (and how said tips stay in the driver) etc are of very high quality. Is it "the best", no. Is it a serious contender, especially when taking price into account - very much so.

[@BarnokRetro]

I was fortunate enough to play with one of these, though not until the mid 80's.... Even then I thought it was a darn good looking machine. The little Sanyo monitor must have come with them, that looks identical to the one I played on. Neat machines.

[@suvetar]

The book Hackers by Stephen Levy has a cool few chapters about this part of computer history, great book for anyone interested in this history, it inspired me to become a career computer programmer! But thank you for posting this, it's great to read about that stuff of course, but to see it in its full glory is awesome, paints a million words!

[@ActionRetro]

I love that book!

[@rager1969]

Wow, Torx screws? Those were pretty new for that time. Funny how they used old slotted/standard screws (as opposed to Phillips) but also used new and probably pricey Torx, as well. I'm sure that was the choice of the keyboard manufacturer.

[@retropuffer2986]

That's just awesome. I love 70s aesthetics. Look at all that steel & wood! ☺

[@Roxor128]

Much more interesting than all the plain black that dominates contemporary devices.

[@LenweSaralonde]

Regarding the random boot issue, check the PSU capacitors. I had the same problem on a modern PC, I had to press the power button several times before it manages to boot, the reason was the PSU capacitors had leaked (I replaced the PSU and it now works fine).

[@Reverieru]

I believe 8bitguy had the same issue with foam pads replacement. After the first approach dirty pads caused keys not to work. He did some other steps and it started to work on him.

[@soniclab-cnc]

Wow. It really is in pristine condition for being born the same year as I. lol. I think my foam has also degraded over the years. I can’t believe how mint that thing is. I would definitely pull the power supply and give it a full work over. Test the rails and the old caps. Larger electrolytic caps do dry up. Check any tantalum caps for possible short circuits. They can become more like resistors over time.

[@Bobbias]

I'd argue tantalum caps eventually turn into low current fuses rather than resistors :)

[@soniclab-cnc]

@@Bobbias yes...usually catastrophically

[@Drew-Dastardly]

I doubt any tantalum capacitors were used on a machine this old. They were expensive exotic stuff for military and aerospace in the '70s. Only in the '80s did they become consumer grade.

[@JohnSmith-xq1pz]

Is that a computer or a Star Trek TOS prop?

[@TaijanDean]

Yes

[@soknightsam]

@@TaijanDean Yes but also yes

[@chironbramberger]

Technically speaking it was the Commodore PET that appeared in Kirk’s collection in Wrath of Khan. Probably an inside joke too as William Shatner did commercials for Commodore at the time.

[@TaijanDean]

@@chironbramberger "Ahh, the Commodore, Vic 20..."

[@joew8438]

Did you know the Apple 1 was also available as a set of technical specifications that Woz published. You coul assemble your own parts kit and build an Apple 1 from scratch using only Woz's specifications.

[@esra_erimez]

God, I *love* this channel!

[@SlightlyNasty]

While I'd heard of these, I'd always assumed they were much more of an Apple-1 homebrew situation inside. That's waay slicker than I was expecting!

[@DougDingus]

If I were you, I would look into a modern switching power supply to replace that monster linear type in your Sol 20. What a great machine! I have an Apple 2 //e Platinum and one of these would deliver a similar retro experience! I enjoy adding cards to improve the machine and or run or write programs, play games. There were a lot of S-100 cards made. Getting a set for your Sol should also prove to be good fun! But, back to the power. Linear power supplies like that run hot, are inefficient and can damage your Sol when they fail. You should be able to find something you can stash in that case somewhere.

[@ristopoho824]

Oh boy that looks just pretty. And the internals too, they are laid out to be easily maintainable and. Well. The layout would probably work for a modern PC too. Not too much ventilation, but there are places where you could make some nice mesh or grid airways. And no i'm not thinking of cutting up an original. More of, making a reproduction case myself. Would be pretty.

[@ristopoho824]

KZbin is sorta bad since reporting these does nothing. And there is not even a choice for scam. Almost feels like they are approving of these.

[@SockyNoob]

This thing looks absolutely beautiful, holy crap. Never knew this even existed. Seems like it had a lot of revolutionary ideas that even later 70s and early 80s machines didn't have.

[@kenromaine2387]

I always loved the Sol-20 's S-100 backplane with the built in extender board connector in the edge of the backplane.

[@markmuir7338]

One additional point to add to your good advice on preparation to powering-on vintage hardware: Re-form the electrolytic capacitors in the power supply the first time you power it. This can be done with a variac to slowly ramp up the input line voltage. This significantly reduces the risk of fireworks and over-voltage damage to the rest of the computer.

[@vernmeyerotto255]

After I got out of the Air Force in 1979, I went to work for a Boulder CO company called The Byte Shop. They were selling small computers for use in business, mainly in word processing. We had a lot of legal offices as clients, for example. One of the machines they sold, and I supported as a technician, was the PT Sol. The S100 expansion slots primarily were used for 4k static RAM boards. They were sold with dual 8" floppy drives, a video monitor, and mostly used an IBM Selectric typewriter as a printer via a RS232 I/O port. They ran CP/M for an operating system, WordStar for a word processing application, and VisiCalc for rudimentary spreadsheet applications. Yeah, even back then, the keyboard was problematic. Pertec 8" floppies used a hammer and chisel for alignment, and Selectrics were a major PIA. Single sheet feeders were Satan's torment for technicians. The huge capacitors were indicative of a linear power supply. TIP: Quit using rubbing alcohol, it leaves a residue that will eventually cause you trouble. Get some isopropyl alcohol for cleaning contacts.

[@AiOinc1]

Woah, is this a tech time traveler video? The SOL-20 is the only 70s computer I want to own. I just wish they were cheaper.

[@rgmolpus]

Proud owner of two Sol-20 computers, along with a Vector Graphics Orange box S-100 computer. Keep cleaning the keyboard PCB - use a scrubbing pad to get the pads shiny. clean and reseat all the ICs. Replacing all the Power supply capacitors is a good idea, along with all the main board electrolytic caps. As the Sol-20 is now, all you have is the built-in 2k of memory, at location C000. You need to add a memory card to boot any serious software. Good luck!

[@ActionRetro]

Awesome, thank you!

[@alexdhall]

I'm pretty sure @TechTimeTraveler may know more about the sol20. He has a working model of the predecessor to this.... the TV Typewriter!

[@QuaaludeCharlie]

Thanks for this trip back to my youth .

[@Steve-bo6ht]

Oh this is fantastic such a fantastic insight on how computers developed from these machines, really appreciate taking the time and restoring the SOL 20 back to it's serviceable condition. Just subscribed and really looking forward to watching all your video's and learn as I go along many thanks.

[@JVHShack]

@Action Retro The @Tech Time Traveler released a video about this very computer a few months ago. If you haven't contacted him yet and want to ask questions about his experience, it would be well worth the time and effort.

[@tarzankom]

I wasn't old enough to own any of these ancient computers, in this case I'm a year younger than the computer, but I still find them infinitely fascinating.

[@ScottDuensing]

What an incredible find. Such a beautiful machine. Looking forward to more!

[@markc871]

Wow, what a machine for '76! Can't wait for the follow up episodes.

[@thelorax9622]

I've certainly read about them, but have never seen one outside of a photo - and although I was 7 in 1976, they certainly didn't make their way to Australia. Good find, mate.

[@AgentOrange96]

The earliest home use computer I know of that you could buy assembled would be the SCELBI-8H from 1974. (Though it was also available in kit form) That being said, it certainly wouldn't have had the same capabilities as this system. Other pre-assembled options at that time would have been designed for commercial use and far bulkier.

[@CubicleNate]

What a fantastic machine. I look forward to the next part of this.... multi part series? Maybe??? :)

[@charlesjmouse]

A look at an awesome piece of history, thank you. There's already been some excellent suggestions about your boot issue; checking the PSU and rest circuitry would indeed be good places to start. How about making this an excuse for collaboration with *Adrian's Digital Basement?*

[@CallousCoder]

That booting issue, some thoughts: Is the reset duration correct? Is the deforming logic always triggering the CE/CS and OE signals always triggering to that eprom after a reset? Last year I had an old Soviet/DDR chess computer that didn’t always properly start and it was an inverter that was floating a bit. After replacing the communist UD something with a capitalist 7403 I believe it was booting consistently. And that wasn’t even related to the reset and decoder logic but just the keyboard. Having “multiple stuck keys” preventing the software to properly run.

[@MaxAcceleration]

11:25 - they didn't see into the future. The future looked back at what they did and made it easier to change in software. Even in the mid to late 80's many arcade games had the same dip switch settings for how many credits each coin was, how hard the AI was to beat, how fast the game play was, clear credit card at boot, etc. These settings for games that survived (Arachnid Dartboards for instance) were eventually all moved to software for ease of changing and also allowing all kinds of other settings that were prohibitive when in DIP switches because of the number of switches that would be required.

[@officermeowmeowfuzzyface4408]

3:27 its not that they don't exist anymore. It's old-growth vs fast-growth, also based on the latitude.

[@SwarmerBees]

Yep. I still own one. Same model as the first micro I programmed on. Other hackers at the computer lab were interested in the Imsai, but I did all my micro work on the SOL.

[@amirhosseinmaghsoodi388]

I thought it's the computer this video is edited on. But this is way cooler. Wow this video was fascinating. First time I saw that old keyboard method.

[@KennethScharf]

Back in the late 1970's, I worked for a small computer shop that was a dealer for Processor Technology, and I helped the owner assemble one of the first SOL-20 computers. The very first units didn't have the built in S100 expansion card cage, just a single slot on the mother board. We were somewhat disappointed that the SOL was designed around the 8080 cpu, and we attempted to upgrade it to the Z80 using an off the shelf adapter that had been designed to work with the Imsai computer. This didn't initially work out, I think the SOL's roms were coded in such a way as to be incompatible with the Z80.

[@Ahamshep]

Hello. several years ago my Father sold his sol 20 and all its peripherals "computalker etc..." in an auction when he moved. This was in Peterborough Ontario. Interestingly the Monitor your using looks strikingly similar to the one he chose to use with his sol. So I have to wonder if this is his old machine.

[@GordieGii]

I was a little surprised that you mentioned the Comadore-64, but not the PET. (or VIC-20)

[@pup_hime]

where do you get a rubber work mat with compartments like the one you have? it seems SO handy

[@Doug_in_NC]

Amazon has them. Just search for soldering mat. They are normally silicone, so you don’t melt them if your iron or solder drips touch them.

[@occupynow99]

Dude please, let's see more! This is fascvinating! Just gotta see it actually run something! So excited you have this machine!! Cannot wait for the next video! Well done!

[@CRYPTiCEXiLE]

Very good video I enjoyed this... the kids of today have a lot of nice tech to play around with they should be very well grateful, but in the 70s it was im guessing wasn't common to own a computer and to have on of these im guessing was pretty cool.. im looking at this and its way before my time since im born in 1982 I remember more like 87 ibm and model m computer which I think are very much a step up from that one, but even today people look at 286 and 386 as old computer hell eve 486 computers that I had at home and play around with and broke some many times and fix what I done stupidly back together ... it was a good learning experience, but man it cost my dad some cash to get it repaired lol ..... but at least it paid off as im still much of a hardcore tinker and very well good at now.... though im not perfect things do go wrong sometimes.

[@GalenlevyPhoto]

Never ever seen that kind of computer before and that capacitor in the power supply is humongous!

[@andygozzo72]

yep, they were big..and far more reliable than many of the tiny modern things, too much miniaturisation! i have several old large ex computer capacitors and are still in good state

[@jordanzish]

There's an article from the late 70's in the Atlantic called Living With A Computer that is probably one of my favourite pieces of writing on the subject of personal computers of all time. This is the computer that the writer ends up getting. The Atlantic has done a fantastic job of archiving their older articles so the article, and many others are still available on their website. Highly recommended reading.

[@RETROMachines]

Love design and blue colors. True retro...

[@geobrower3069]

12:36 They're called slotted screwdrivers and the screws look to be pan-heads 20:09 (and earlier) that module may be a key bounce killer, the pot being there to adjust the time for the de-bounce. The jumpers you talk about along with piggy-backing ICs on to each other (not seen on this comp) was very common in the 70's to 90's to correct issues and modifications; Lord knows we did many hundreds of them on the video games of that era! 21:30 First step before powering-up old electronics is check the caps for leakage, but the second job is pull the ICs and reseat them to cut through any corrosion along with any wafer or unsealed switches.

[@jecelassumpcaojr890]

This is a great computer and a great piece of history. Note that the less successful Sphere-1 computer came before the Sol-20.

[@Coillcara]

Wow 👌 such an amazing design for 1976 home computer!

[@mikekwayne]

Soldering?! those guys had it sooo easy! I go back to wirewrapping! :)

[@westerp]

While I understand you enthusiasm, but in olden times they did indeed have system software (OS if you want) in ROM. Eg. C64 and Apple2. Even the 68k-generation after that like Macintosh and Amiga had most of the OS functionality in ROM to keep the memory footprint of OS and software down.

[@jimsteele9261]

Glad to see one of these working again... I remember seeing ads for them back in the day, but never saw one in person. I didn't know it was s-100 either. I still think the S-100 bus should be called the Altair bus, they invented it. But the other builders didn't like referring to the competition in their ads so they renamed it "S-100". I built an S-100 machine from Kilobaud magazine plans back then... those were fun times. Every once in a while I think about digging it out of storage and doing a "anachronistic upgrade" to it. Like replacing the 2102 and 2114 static RAM with a single CMOS RAM chip, and replacing the 2116 EPROM with an EEPROM. And replacing the linear power supply with a switcher salvaged from a PC/AT.