I love how the retro computer community has gone from being 'ooh lets look at the games' to 'can we use google with them'. The never ending tinkering is so interesting to me.

I'm digging way back in my memory but the problem you are seeing with expansion RAM may be due to address space. The Processor Tech Sol 20 used an 8080A and only had 64K of address space. The personality module and 1K of SRAM occupy the top 16K window of address space. That means you ONLY can add 48K or RAM to the S100 buss before it overlaps the personality module and onboard RAM. To work correctly, you need either a smaller RAM board (16K for example) or you need to disable the top 16K of RAM on the 64K RAM board. It's been a long time since I owned one of these but I think that might solve your problem. Good luck. OH.. and yes. That was the game of life. NOTE: A few of the one person shooter games included sound effects, even though the SOL-20 did not have a sound card. To make those work, you sit an AM radio next to the computer and tune it to the low end until you can hear the sound effects. (there will also be no small amount of ambient noise mixed in) But... it works. I wish i better remembered the frequency to tune the radio to. It's rather finicky so you have to play with it a bit. One of these games was the game of TARGET (TARG). You will find the game code and manual in the GamePack on the SOL20.ORG site. Processor Technology sold expansion cards for S100 machines other than their own so don't let that fool you. This 64K card was probably never intended for use in this computer.

Definitely thought you said ADHD powerhouse, not 8080 powerhouse. I’ve never felt so seen 🤣🤣🤣

I'm so glad that RTFM still applies to a 47 year-old machine!

Awesome video. My dad said that even when those machines were new, they were very temperamental

The LOCAL key is so that you can type at the machine while it is in terminal mode. In the old days of teletypes, this is for doing things like punching the paper tape with some extra content in the middle of a session (without transmitting that content to the remote end). In the era of a smart terminal or a terminal program, it might actually be for entering terminal program commands.

Oh yeah! Was waiting for my weekly dose of totally normal computing!

Now THIS is why I'm such a fan of this channel. Nothing quite like learning about a new computer one week and trying to exploit it the next

Back around 2010 I picked up a Sol -20 from my community college in a surplus sale for $5. it needed keypads and the display was slightly corrupt, but I flipped it for almost $2k on ebay as-is. Kinda wish I kept it, but it was great financial help getting through college.

I'm old enough that when you said "Lee Felsenstein himself responded..." I was _really_ impressed! That's like having Woz respond to an Apple II question 😃

Computers like that really make you appreciate an Apple ][ or a VIC-20.

Great lessons learned about the LOCAL key and SPEED throttle. Congrats on first steps in getting any software into the system. On the last page of the SOL-20 manual, IIRC there was a price list of all the various accessories (which quickly got very expensive, $3000+ in '75 for a functional system with data storage, 4K+ RAM).

Have to say, when shopping for a computer I do tend to pick the ones that have that essential "Screen and Keyboard" upgrade. Sure beats your traditional LEDs and front panel switches. 😁

Uploaded 53 seconds ago? *immediately clicking it*

I learned to program computers for math, physics, and statistics in 1976-77 on mainframes on a university computer. I went on vacation in 1977 or 1978 summer in the USA and Canada and visited computer stores that sold and demonstrated the Sol Terminal computer, and used one while it ran the Trek game. I also saw and used the IMSAI 8080, and the Mits Altair 8800. S-100 expansion bus issued unregulated DC power so that each expansion card had to down-regulate the supplied power to whatever was needed on the card for the IC chips used on the card. Vintage MOS LSI ICs often used +12, +5, ground, and -5 volt supply voltages. Start with testing the voltage output from your power supply--both positive and negative supply rails. Then start checking the output side of both of the power regulators on the expansion card. I have found that Zener diodes that set the reference voltage for the regulators often fail in the aging process (oxidation, heat, radiation, etc), and could make everything else not work, and hopefully not fail also, otherwise, a lot of chips got smoked in the process. Electrolytic capacitors explode when you apply a reverse voltage, or if you allow an over-voltage situation to happen. Lower quality capacitors have a parasitic resistance known as ESR = effective series resistance that would cause such a capacitor to fail due to internal heat build-up. There are such things as ESR meters that measure the amount of ESR in capacitors. The raw supplied voltage if I recall correctly was +16 VDC and -16 VDC or something like that. These should have a slight ripple voltage that is supposed to be addressed by the large electrolytic capacitors. The worse kind of power supply regulation was used--linear power regulators that dissipated a HUGE amount of heat requiring heat sinks and fans to mitigate against bipolar junction transistor thermal runaway. The better way is to use 20 to 100-kilo-Hertz power MOSFET switch mode power regulators that filter the output regulated voltage with a choke coil and capacitor low-pass filter network. The MOSFETs then shall require less heat sinking due to higher orders of power regulation efficiency due to power conversion technology rather than dissipating the excess voltage power being supplied. MOSFET = metal oxide semiconductor field effect transistors. The connectors on such a device are as follows, Gate = input signal to be amplified, Drain = input power source, Source = output power signal. The Gate input pin on an Enhancement mode FET often has an input threshold voltage before the transistor even starts to turn on at all. Power MOSFETs have different kinds that work differently. Enhancement mode and depletion mode. Most of the ones that I saw in common practice were enhancement mode. Buy a book on Switch Mode Power Supplies. It shall explain the various kinds of designs used for different applications. An SMPS shall draw less current from your main power supply which in turn shall draw less power from your wall socket. A power mode bipolar junction transistor is a low-frequency amplifier often used in linear power regulators. Power loss is the mechanism used to reduce and regulate voltage levels. Power = voltage x current. Power loss = input power - output power. The bipolar junction transistor mostly just acts as a variable resistor so that the power drop seen across the device is dissipated as heat that must be heatsinked for cooling purposes. The connections for such a BJT are Base (input signal to be amplified), Collector = higher power voltage input pin, and Emitter = higher power voltage output pin. The trouble is that the Base input signal gets a HUGE amount of thermal power leaking into it as an unwanted noise signal that can make the transistor turn and stay fully ON rather than staying only slightly ON letting only the desired amount of power through it. To mitigate against this happening, a bias resistor has to bleed or extract this unwanted thermal noise signal out of there by connecting this bias resistor from the Base to Emitter. When I was young and foolish, I did not know about thermal runaway found in BJT-operated linear power regulators so did not use a lower resistance (higher wattage 100 Ohms or so) bias resistor to mitigate against this thermal runaway leakage signal entering the Base junction diode and 24 volts ended up being sent into a circuit expecting only to have 12 volts DC on its supply rails. Luckily for me and my friend, the owner of the computer system, the circuit being powered did NOT blow up right away and survived the very bad ordeal. I learned to use the SG3524 and SG3525 SMPS regulator ICs by using the manufacturers' application notes for use with either BJTs or power MOSFETs. If I recall correctly, I used these in Buck designs. They explained that for certain applications a power MOSFET gate has to have an input signal that might have to exceed the input supply voltage by about 5 to 7 volts to insure that the MOSFET is turned fully ON. To have this happen, a small 0.1 uF signal ceramic capacitor can be used to temporarily hike the input gate voltage used for turn-on switching. To know the circuit configuration for this you have to consult these application notes.

We had one of these we built in our computer lab at IVY Tech Indianapolis Indiana campus from1976-79. I think ours was upgraded with a Z80. We handkey loaded the Trek game, which was a text based Star Trek game, into it in Hexadecimal / machine code. And yes, game audio was available by setting a radio next to the computer and you could play with the radios tuner to get a variety of different sound effect schemes. You could also save and load programs into memory via an audio cassette player just like the old commodore did.

When you read from address 0, you received a page full of FF. That implies the memory isn't outputting to the bus at area. There may be a problem with the chip select logic or a bus transceiver. Also be aware the the S100 "standard" was more of a guideline. Ram and rom cards sometimes need configuration or modification beyond just addressing to work properly with a particular system. You'll need to reference the documentation for both the ram card and the Sol to understand how it needs to be configured to handle memory reads and writes. The S100 bus came from the Altair which had a full front panel that handles memory reads and writes. When later systems stopped including the full featured front panel, memory read and write circuitry changed and was not always done the same way across different systems. Add in shadow memory and bank switching possibilities and you end up with a lot of different ways that a memory card can be configured. If that single card has a full 64k of RAM, I'd suspect it was made pretty late in the s100 era. There are likely a number of different ways it could be configured to meet the needs of the system it's installed in. If it wasn't originally installed in a SOL20, there's a good chance that it's not configured correctly for the system. Also remember that the 8080 can only address 64k of memory. The internal ROM and RAM shouldn't be allowed to occupy the same address space as the expansion RAM at the same time. You'll need to disable the ram on the expansion card so that it doesn't overlap the internal RAM and ROM.

8:29 I'm surprised the USB to RS-422/485 serial adapter worked at all, since afaik the SOL-20 has a RS-232 serial port.

Enjoyed the two videos. Thanks. Beauty of a machine. Cheers.

This is a great find!

Just discovered your channel. I was on the edge of my seat for all of this -- I remember Poking values directly into TRS-80 Model 1 memory, and using the VARPTR to (try to) run assembly programs. This really took me back to how exciting and nerve-wracking all that could be. Thanks!

Would love to see a Lisa 2 with upgrades and running MacWorks MacOS. Maybe get ahold of a twiggy drive.

This was outstanding!!!!!

The fun was the bits we bit along the way. 😊

Yay! Its new video! Now im not bored and i can watch something fun and interesting

I love your Mac videos, but it's really great when you mess around with other non-mac systems. Looking forward to the next episode with the SOL.

Solid! Top KEK! Peace be with you.

Good stuff! I never thought that when I went through this exact pain with my Exidy Sorcerer 4 or 5 years ago that people would be interested in watching such a fight.

You need to source a drive controller and add a GoTek Floppy Drive Emulator. DO IT!

The Sol and that display make your decade-old ThinkPad look almost indecently recent!

The Local key allows you to only enter data on the Sol keyboard, or 'locally'.

That's nuts!

This brings back memories… I didn’t have something this old, but had a Tandy 600 in the late 80s that I used at work and only way to get data off it to use on real PC was with null modem cable and terminal software. This computer seems like a project worthy of recreation with new pcbs and newer components like the C64 clones.

In HS 1984 we had cardboard box kits. They had 256 bytes of ram with a 8 character LED display and a KB with 12 keys like a phone pad. You typed in the code and ran with results on the 8 character LED display.

"Conversion technology", eh? That serial plug combo reminds me of a Jenga game I played once...

I want one so bad now lol. What a beautiful machine. I wonder what games are out their for this beast

It's pretty impressive how much this can do compared to an Apple II, despite the Apple II being the newer model and set the standard for computers at the time.

Pushing 50 years after that thing hit the market the original designer is still personally answering tech support requests.

Built like a tank, battles like. a tank good ol' old retro computing :)

2MHz?! Such luxury!!

I remember seeing these back in the day when I was looking in the market for a laptop. I was already familiar with GEOS from my old Casio Z-PDA as well as my Commodore days. A budget Windows laptop went for around $2000 when these were released so there definitely was a temptation to save some money, especially if your primary usage of a portable was just simple word processing. In the end I went for a Fujitsu Montego Windows laptop on which I would eventually install Slackware Linux. I'll always have a love for GEOS though. Very capable for a lightweight OS.

The last video was so long ago I had to go rewatch it, I remembered the machine, but nothing about it, lol.

I feel like you're stepping on both LGR and Adrian's toes with this one.

Dip Switches, Foam Pads, & a 1200 Baud Serial Connection, what could go wrong ? Well apart from Exploding Capacitors... That's why Fixing Old Computers, can be such a Buzz, Especially if you Are Not Grounded.. However it is a Constant Reminder of why WE Upgraded the Equipment, as soon as something better was available ;)

I threw my SOL-20 away. I cry now, when I see your beautiful machine. But it would have been an incredible time sink, and my calculator has more computing power... since the 80's.

Best Author

Regarding the RAM board... When those caps exploded, they probably took the regulator chip with them. I strongly recommend verifying that the power supply on the board is putting out the right voltage (5 volts), or it's game over. Also, as others noted, you can't have overlapping memory. I'd start with limiting the add-in board to 32k to start with, and also check the SOL manual to be sure there aren't any jumpers on the SOL Motherboard that need to be changed to accommodate the add-on RAM.

That terminal would make the greatest Sleeper Gaming PC known to mankind

"Local" was also a rotary switch on the Teletype we had at highschool.

That computer is the same age as me... So the breathlessly incredulous way you stated the age of the machine made me die a little bit. That wood panelling is mwah *chef's kiss*

Magnificent

Good Job! 🧀🐴

I remember when some 286 computers were limited to 640kb ram. I had trouble imagining how older hardware was. Great video overall.

You really need to hook up a modem to the Sol that's on auto-pickup so you can dial into it and communicate with it. Say, it could show you what the digits of pi are. Then you might be doing something that requires the value of pi, and then you go, "Better call Sol!" and then you dial from your current computer up to the Sol to display the number pi.

Was rooting around today and came across a circa 1978 cassette tape with recordings of music created on the Sol-20 using the Music Compiler and board that were available at the time. If you are curious, I'd be happy to send you a link to the digitized audio file I made from the tape. Feel free to post and share or not as you see fit. It's interesting to see what could be done with a machine this primitive and using, basically, only software to toggle the state of the processor status line in the S-100 buss. The physical card had only 2 active lines. Ground and Processor Status. These were filtered and voltage adjusted by a small number of capacitors and resistors and then fed directly out to an RCA connector for "LINE level" recording or play.

Just FYI. For those who have a Apple II you can load ADTPRO via serial cable into RAM. Then it runs the program so you can create a disk. I had a blank disk and working drive. So it was fun to do that. They Call is serial boot strapping.

That was funny. One one creators just said to you. RTFM XD

I wonder if the memory card you were using was working properly but was configured to map its RAM over a conflicting area of the memory space. If it's overlapping with hardware registers, then it wouldn't surprise me if that would cause unusual behavior, especially if the memory card is refreshing the RAM using writes.

Godbout Electronics (and later CompuPro and Viasyn) This is for memory and other things. Had 4K memory S-100 board from this company. Currently staring at a ‘Seals Electronics’ 32K S-100 memory board. This one had an issue with bypass capacitors, and was missing two that we’re not designed in. Had to add them, after that the board worked. Got it off a discount table years ago (78).

I'm going to create a game, but the goal of the game is to get the game to start, and once you achieve the goal, it tells you "Great Job! I hope you enjoyed the game! "

personally when dealing with vintage tech especially of 60's and 70's builds hit with a uv light looking cap failure.. the leaking fluid from these caps may not be seen by the naked eye..

wow, its amazing we kept at it with personal computers.....

It was a good journey

Nice

So invested in this 😆 will it play Doom? 🤔

Looking at the memory dumps and without knowing the actual specs of this computer, I could see that it was at least Intel / Zilog based. My original guess was that it was a Z80, but considering the release date, it would have been a very early Z80 computer, I realized it must have been one of Intel's own CPU's. It's a fascinating piece of equipment.

Ran a $100,000 a year business in 1979 on one of those, Dual Floppies, a printer and some custom loader software for Basic.

I remember seeing these machines at computer shows in Earls Court London back when I was a teenager, I was impressed with the build quality and the huge price tags! Other names from the time were the Compucolor computers which I never hear talked about, and of course the huge number of S100 machines. I always yearned after the Ithaca Intersystems DPS-1, mainly because it looked like a minicomputer with its switches and lights on the front panel, it was much cooler looking than the (older) Altair. I'm not sure that many SOL-20s got sold in the UK, due to exchange rates they were pricey and by the time they started advertising them here there were plenty of alternatives in S100 computers. Most of the potential customers were businesses replacing or augmenting minicomputer installations, so needing a terminal was less of a problem, and the hobbiest market in the UK favoured much cheaper machines, it didn't really take off until the PET, TRS-80 and things line the Compukit UK101 came along. Then Sinclair came out with the ZX80 and ZX81 and those became the sort of machines that fired up the hobby market.

"Local" normally shuts off the echo to the screen. The data is still moving just fine. That being said. It shouldn't have an affect if TeraTerm is considered the host side. So... That's weird.

I think I need to watch this...since I won this fascinating computer. My first computer experience was with the TSR-80. (I forget which model but one of the earlier ones.)

I'm sure someone probably mentioned this already but you many want to change out all those tantalum capacitors before they also fail on the memory card. Good luck!

Havent seen serial converters like that for a few years. I used to have a big collection to twist, change gender, convert etc

I hope you get the ram expansion working.

"We're going to do what we love to do on this channel!" I was thinking, break things? Cause things to explode? Then, sure enough, he did cause two caps to explode, albeit off camera. Showing my age, the first modem I had was 1200 baud. My older brother had a 300 baud modem, but that was too slow for me.

LIKE SCREEN! AND KEYBOARD!

I bit of advice: Keep your greasy mitts off the gold S100 edge connector by handling the PCB by its edges & follow some ESD precautions to prevent unwanted & unseen damage this prime vintage specimen.

I haven't seen a SOL since when they came out and Processor Technology was wiped out once the Apple came out. PT had a huge office building and was expecting to be a hit. But as I recall it was very expensive and had a weird OS. How did you get it ? I knew someone who bought one brand new way back in the 1970's.

hope you get the memory expansion issues sorted

if you set some parity bits, you'd get better error correction... 1200 bits/s at 7odd1 should work nicely.

Address 0 is where the interrupt vectors are in the 8080. You're not supposed to load programs there.

Squarespace should host all of these sample websites for people to randomly find... imagine mis-typing a web address and finding one of them...😂

A spacer fills a gap. The foam pads are under compression, so I think you used a shim :)

The programs gave you a clue about the memory card issues. From looking around, C800 to CBFF is user/system RAM, and from there to CFFF is video overlay. Nothing mentions what's done with D000-DFFF, but the first program you tried to load started at E000. That implies to me that the memory card needs to have a base location of D000 or E000, and you'll get 8 or 16K out of it with the rest inaccessible beyond FFFF. The author of the program obviously had that space addressable and available, so it can be done... somehow. If 0000 is unallocated address space, you might still be able to use the card but you'd have to disable any overlap with existing allocated/utilized address space.

I remember the time when you only show hands instead your face when explaining and I can say that you should have done taking head style videos like this much earlier! Great job.

I wonder if lower memory addresses could be system reserved maybe you need to increase where the entry point is

Interesting.... I'm absolutely no expert on this system! FWVLIW: Of course there's a good chance you'll have some bad RAM on that memory board that will need finding and replacing, but another thought: The Z80 can only address 64K, I presume the personality module ROM will be mapped somewhere in that 64K. (likely 0000) Add a 64K RAM board and you're going to have a clash. It may be you need to map out any RAM that occupies the same addresses as the ROM... at least for starters. Also be sure that whatever address you are loading software to isn't where the ROM or any system variables live... at least for starters. Um, unlike the 6502 that treats memory and I/O as the same thing the Z80 does have separate addressing for each... but some Z80-based machines were still designed to map I/O to memory locations anyway. It may be worth checking the SOL isn't one of these - if so that might mean another block of memory addresses where you don't want any RAM.

@11:08 FARTS !!! Yea Farts. How did you know what I was doing in my chair while watching this video? Who wants to come help me smell them? LOL PS... I am a grandfather and I am turning into an old fart HA HA HA

Awesome video! Edit: Is that the LTT screwdriver at 3:36??

I'm fully expecting this thing to run some flavor of Linux by the end of the month...

There are more transistors in the USB to serial converter than in the whole SOL!😄

Did you clean the golden finger on the memory card and the slot it goes in?

Screen was the best invention since Log!

Remember that the I/O is probably memory mapped. you cannot use a full 64k - the 8080 memory space is only 64k, you already have some ram, rom, and I/O mapped into the space. I don't remember the details... we only had a 16K card, so no issues. You will have to look at the SOL documentation,as well as the docs for the card. Not every S-100 card was identical to the S-100 machine (i.e. cromemco might have a different memory layout) so you will need to configure. Consider reducing memory to 32k or 48k and see if you can make it work.

70's people when this came out: Wow! I can't believe it has a keyboard and screen!

Persci dual floppy damn spellchecker

Those characters looked like cryllic letters. I wonder if your card was modified by a soviet or even a bootleg. It was missing an entire switch array and that was the time soviets were buying our off the shelf computers and reverse engineering them.

I just broke out my SOL-20 today and was having a problem getting my Terminal Program to work properly. I have a regular USB to Serial adapter and a 9pin to 25pin NULL MODEM cable. Teraterm was setup for COM6 2400 8 None and 2. I assumed that would work. It didn't. :o( So I tried a couple of cables and adapters and watched your video. I did not take the system apart to look at the dip switches. I just changed the Teraterm settings to 9600 8 none and 2 and that worked. I guess the settings that were saved in my Teraterm were setup for another computer. I should probably label the back of my SOL20's serial port, so that I do not run into this problem again...

there's a concert venue in south indianapolis that actually has one of these on display, no idea if it works or not though.

Hello, Sorry I am at a loss as to where to look for an old program, back in the days of duke nukem there was a program that would allow us to look inside of duke nukem and change code if someone told you what to do, for example there were laser bombs that there was a code you could change in duke nukem to make the laser invisible. I think that program was called a monitor program but I think it was called something else before it was coined as a monitor program. I am trying to find this program, any help? Thanks

Did you try blowing on the connectors of the RAM expansion card? It works for NES cartridges. Sometimes. Maybe. Has happened.