The IMSAI was already painfully obselete at the time WarGames was filmed. This was deliberate, to show how resourceful Matthew Brodrick's character was as a hacker even on a student budget with really old equipment.

So clever using the Arduino.

Thanks for the video. I was reading 'Once upon a time in Computerland' and was wondering was the heck this machine was (And yes I'm old, my first pc was an Apple II+ in 1982)

HDOS from HealthKit was a far better os than MSDOS… source code was available and modifications to the overlays was easy

I had modified the rom os to using hex instead …

I hear that Chase (and Berzerk) were inspirations for the game Robotron.

My first computer. Bought it 2nd hand back in 1988. Best purchase of my life.

That was our first computer in high school, and had been there a couple of years before I got there in 1981. The SOL had the Helios II 8" floppy disk drive and the Diablo printer, and as the printer was *not* the dot-matrix type - it remained the go-to machine for doing English essays and the like even after we got the 8K Commodore PETs and later on the dot matrix printers for them. I loved the SOL. The games were crude (as per 'Robots' here in the video) but it was a solid machine and didn't feel like a toy, which the early Commodore stuff did - although it won in the graphics department. The only problem I remember having with ours was the Helios drive would go down about weekly - and from what I understand that wasn't an uncommon complaint. One day I'll find one within my price range.

Thanks for posting this video about this important machine. With a base price of $1800 it was too expensive for home use, [In 1978 the MSRP for a new Toyota Corolla 2 Door Liftback was $3,388]. Was the Sol-20 primarily used by small businesses?

The music program for the PDP-8/L in High School was much better. There was also a 4-part version.

Hey Guys, are you ever going to do a video with your KEMBAK-1??? That would be Awesome !!!

Thank you for this fascinating look into computer history

I build a Sol as soon as I saw and advertisement in Popular Electronics . Fun to assemble, but switched to an Apple II when it came out. Very fond memories of the Sol....

Exvellent video.Thanks!!

I bought one of these at a San Diego swap meet around 1982. It had a minimalist ram card. Was never upgraded. Came with an H19 terminal as well. Bought the combination for a grand total of $30. It was in mint condition. Bought a 300 baud modem from radio shack, it was my first venture into online computer communications with bulletin board systems (BBS). Funny, I didn't need the H8 to use the modem, just the H19 terminal. After a while I wanted to create a better memory card that would accommodate the 8080's full capabilities. So I designed one, used radio shack sourced circuit board decals. It was a lot of work, but I wanted to do as close to 64k as I could using a newer static ram chip (I think 4k each?). (details are foggy from those days). Every payday I would got to the local electronics supplier and buy another ram chip or two. Static ram was not cheap! Dynamic ram was super cheap but was too complex! Got the board etched, drilled, and filled. It was simply a proof of concept for me. I think I ended up with about 16k of memory on it. When I initially tried the thing, it was wonky as hell. Half the data would store, but the other half wouldn't. I'm like wtf... Was in the Navy at the time and on a waiting list for air controllers in training to go live. There were a lot of people ahead of me that had to deploy, so I had a lot of time on my hands. Went into an empty classroom every day and used the whiteboard, along with Intel data books (the really thick ones back then) to understand what I had done wrong. In the end, I had missed a timing issue, of issuing a hardware write to the chip. You just cant send a write command to a chip and expect it to respond immediately. Doesn't work that way. It takes a milli or micro second or two for it to be ready to accept the data. Fixed it by putting two inverters in series with that line to introduce a fake delay. It worked. The stuff we throw out yesterday. Who knew what their value would be today. We never learn.

Awesome video, I just realized that an S-100 based single board computer I had in my collection was in fact a Sol-PC board, the board from the SOL-20! The person I got it from had it since 'new' in the late 70's, he was a Engineering major and I was lucky enough to be the recipient of a lot of his older stuff before he moved when he retired including this fantastic piece of computer history. Since what I have is just the main board itself with the personality module - I don't even know where to start to refurbish and test this thing out, do you?

I have all of the source code for HDOS, the assembler H8ASM, the BASIC H8BASIC and all of the ancillary modules including the boot ROMs and device drivers for the printer, general serial port, 8 and 5 inch floppies (H-17, H-47) as well as the 10m hard drive, the H-67. Coolest feature of HDOS was a clever file format that added *.REL and *.OVL files to the usual *.COM (aka *.ABS) file extensions for code. This was a way of creating relocatable code that could be located anywhere in RAM no matter the amount of memory. The file header pointed to a table of addresses within the code that would need to be corrected if the program was loaded 2nd or fifth. Like loading the BASIC and the ASSEMBLER at the same time. As you added RAM you could go from 16k to 64k and did not need to reassemble the programs. The overlays allowed normally unused OS apps to be loaded to top of memory only when needed. Far ahead of it's time and the dev is almost unknown. Far smarter than Gates but not as ruthless. Thanks, J.G. Letwin.

I remember the 2k low loader monitor ROM in the H-17 floppy drive that was copied in hardware into the first 2k of RAM. it came with a 4k SRAM or 8k SRAM board out of the box. If you had at least 16k of SRAM you could load rhe ahead of it's time HDOS operating system.

Your chabbel is pure gold man!!i really thank you a lot for uploading all of these. Hope to see new videos in the future!! Greetings from Argentina!

The serial card available from Heath for the h8 could operate reliably up to 19, 200 baud. It was not unstable when connected to compatible rs232 devices. The instability that you spoke of is based on your setup not the fact that he's card could not handle those speeds correctly.

This was my first computer that I bought in high school in 1977. My dad paid half for it. I loved this machine - built the kit, learned to code with it - but I threw the computer and the manual out when I got my first Mac 128K in 1984 (after sitting on the waiting list for several months). Owa tagu siam.

Thank you for this trip down memory lane. I never owned one but I spent my childhood reading Heathkit and Edmund Scientific catalogs because we were too poor to actually subscribe to paid magazines haha..

I also would be very interested in details about the Arduino interface.

I was a Zenith computer technician. Nice Heathkit H8, it was fun programing in offset octal keypad than hex. This brings back so many memories. Thanks for the nostalgic video.

it had no programs or software! it was in binary and only used by TRUE GEEKS! the college had one for students to play with but the plastic buttons broke on it and could not be replaced.

Somehow I ended up on the weird side of the internet, found out about Sol20 computer on instructables. I had to see it in action

Actually, Heathkit did offer the H8 in fully assembled form for more money - I have a sales brochure for it as well as one of the machines and tons of documentation and software for it. I would be interested to know what the Adrino is doing... is it just acting as a terminal emulator for downloading the files because your Mac terminal mode doesn't have that function or is there more to it? Could I just use a full fledged terminal emulator like Kermit instead?

Hence why the FCC required RF Sheilds... To prevent RF spillage from the CPU Clocks onto the AM Band.

Thanks for the intro. A good friend of mine has 2 of these from his fathers estate. I am going to be checking them out soon for functionality. I got started with the Heath H8 back in the 70's and later was an FE for Digital Equipment Corp for years. Loved the PDP 8's back in the day !!!

The Sol-20 was the first real Homecomputer i.e. it would come fully assembled with a ROM and a keyboard and a TV output. It was very sophisticated but was quickly made obsolete when the Apple // came out in mid 1977.

Would very much tech data on your ARDUINO interface and software.

Love these videos! Thanks!!!

I remember when the Sol-20 first came out and I wanted one so bad <3

You can hear a remote control send data by holding it near an AM radio.

Found Gold

I think a lot of this old computer technology is really interesting, but unfortunately only a very few people will get real hands-on experience with it. However, with a Raspberry Pi, many of these older computers can be emulated. Its not quite the same, but even emulated computer can be fun to work with! Btw, really enjoyed the video ... :-)

I remember seeing the SOL Computer at a Central Florida Computer Society meeting, probably sometime in the late 70s.

Hi there. Can you add a link or more info for the serial/terminal system system you have set up? Is it “cutter”? What hardware is that? ThNks!

Lindo.. great

i heard of this computer its my grandpa's

I've never heard of this computer. It looks great

Love the look of this machine, thanks for sharing

The H11 paper tape reader was NOT the most common external storage device. FAR more common was the cassette interface that was integrated on a card that also contained a single serial port designated for the original H9 (upper case only) terminal. The cassette interface ran at 1200 baud, 4 times as fast as the cassette interface for the Altair/Imsai machines. The interface could be operated with a single cassette machine (R/W) or dual machines which greatly simplified operations. The cassette machines sold by Heathkit were General Electric branded. They served the H8 community well until the advent of the floppy drive interface later on. It's also worth noting that the BASIC originally supplied by Heathkit (named "Benton Harbor BASIC" after the headquarters city of the company) was a custom 'dialect' of the language unique to the H8. You had to carefully comb through any source code written for a different machine to eliminate invalid commands or syntax. This problem was eliminated by the eventual adoption of a custom version of the original Microsoft Basic interpreter. This program allowed source code written in the Microsoft dialect to run on any machine that had a version of the interpreter written for it.

Great video. Never heard of this computer before.

Awesome dude, thanks so much for sharing. I'd heard the stories of music played from early homebrew PCs thru radios but had never seen it done until now. Well done!

Nice video! Very informative:)

Very cool. Thanks for showing it to us!

No need to turn the system off then back on to do a reset. You simply need to press the RST and 0 keys simultaneously on the front panel. I heard you mention the paper tape reader as an optional peripheral but most people started out with either a single or dual cassette tape recorder system to store and load programs. Ah, the good old days. I still have my H8, my H19 and my dual 100k disk drives - many, many hours spend with those systems back in the day.

God save you if you use that tron command on a teletype.

Hello. I still have my H8 that I built when I was 16. Would you be willing to share your Arduino interface information? I'd love to get my computer operating again. I did restore it and had to replace a few bad caps. Unfortunately I no longer have the H19 terminal.