IMSAI 8080 - You know that computer from War Games 

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Thanks for bringing back good memories! I remember the IMSAI 8080 with the operator panel my dad built one from a kit in early 1977 he got from The Byte Shop. He ordered his kit with the Zilog Z80 option, direct connected keyboard and interface card, 16K memory card, a cassette card, an I/O card. After a year he brought home a Micropolis 1053-2 dual disk drive with card and a Dazzler graphics card. The first "monitor" was a B&W 13" TV he modified for use with a composite signal (until he got a color TV after the Dazzler was installed). The boot sequence for the tape was the only thing I remember doing before the disk drive. Far left four blue switches-UP, 1st red switch DN, and second red UP then pull the RUN/STOP switch UP and it would load from a cassette recorder. I played a version of the Star Trek game on that computer that opened up with Admiral Fox greeting the player. Can't remember which version of the game it was and have tried to find it but haven't been able to. I played it for years until I discovered the world of BBS's after getting a Commodore 64 with the Datasette and Vic Modem for Christmas 1983. Yes. Good memories indeed! Thank you!

Yesss. In bed sick on a weekend but new RetroBytes makes that okay!

I worked in highschool and later college for a small startup in Colorado that had an IMSAI 8080. They did some amazing things with that computer before finally moving their development over to apple 2s. They had everything from editors and compilers to paper tape readers/writers along with other storage and video output peripherals. I think their first assembler for 6502 on Apple2 was from this IMSAI. Good memories.

'70s computers with rocker switches are the coolest thing ever - which is a striking contrast to '70s electric organs with rocker switches. Those just remind me of being bored out of my mind at my grandma's house in the scorpion-infested outskirts of northern Tampa while my grandpa tried to play church music on his 1981 Omnichord, occasionally pausing to tell me to stop horsing around.

Really cool! This was the Cadillac kit, as we built the 8008 based unit published in Radio Electronics. With existing experience in broadcast automation systems using huge wire wrapped shift register memory boards, it wasn't too bad to construct. I had a friend that was a salesman for Shafer Electronics, so free mfg. reference manuals were available. Back then, these books had the complete instruction set in the appendix. Later on, I found myself working on the first American made audio mastering consoles from MCI (later bought by Sony) with motorized moving faders, using the famous Z80 as the programmable controller. As engineers, we preferred the Motorola 6800 CPUs, as they were more UNIX friendly. Apple adopted the 6800 for the Apple II, and I worked for a local shop called, "Computers and Things" that was an independent and the first Apple dealer in Austin. What an era!

Part 2 (comments re War Games from an IMSAI owner)... If you look closely, you will notice all the LED's on the machine are always lit. This results from the fact that there's no CPU card in the machine. When phoning, he puts his telephone in an acoustic coupler (300 baud max), has a box labeled IMSAI 212 (1200 baud max and never built) and then gets data at what appears to be 9600 baud. Either Todd Fisher or Nancy Fieitas (excuse spelling) who provided the IMSAI stuff apparantly insisted that they use two hands to close the doors on the CalComp drives... If you just push down on one side you tend to break the door...

Always excellent, thank you. FWLIW: On the subject of surface mount soldering from one person who doesn't do a lot to another. The 'trick' is while through-hole needs accurate soldering rather than component placement, surface mount is all about accurate placement while not giving a damn about the soldering... use a crap-ton of liquid flux, tack the corners, drag a seemingly stupid amount of solder over the pins and pads, then drag a clean iron (+/- good wick) to mop up the excess, adding more flux if the pads aren't still swimming. Repeat until all the bridges are gone! PS: Hot air is another technique again that also takes a surprising lack of care as long as there's plenty of flux on hand. This time flux, solder, flux the pads, place-ish the component, more flux if not swimming, hot air... and assuming you didn't blow the component away with too much air flow you'll know when it's done because the component will 'jump' in to alignment for you. Check for bridges and remove any with the tip of a clean iron. (flux!) ...most people who teach these techniques are pretty good at it so understandably get away with less than desirable amounts of flux (and solder) because that's quicker and less expensive. For the occasional solderer it's best to go ham with the flux, use more solder than you think is sensible, mop up the excess, and not cry about the time or waste.

Outstanding video! I got into computing in 1977 (the year of Star Wars) with the Radio Shack TRS-80; which would later be called the Model I, just as Star Wars would come to be called Episode 4, A New Hope. (Don't get me started!) My model had a 4K, Tiny BASIC on ROM, 4K of RAM, and a monochrome all-uppercase monitor and a cassette interface. I mention all this because we early computer hobbyists were aware of the Altair, IMSAI and Northstar systems, but didn't know much about them because we all had our own different Users Groups to go to. Which is why I'm so happy to find this video with such a nice explanation of the IMSAI. All good wishes.

Brings back memories. Bought one as soon as they were available back in the day. The old S100 bus (I guess more of an 8080 bus, to be exact) cards were big and not too crowded so soldering wasn't that big a deal. Got tired of keying in programs on the front panel so built a point to point wired ASKII keyboard and initially used an old Type 33 teletype as the output. Eventually added a couple of terminals and 8 inch drives I salvaged from somewhere. Great memories. Mine never talked like the one in War Games, but then the IMSAI was obsolete by the time War Games came out, anyway.

I came into the hobbyist market one generation after the IMSAI. That machine just looked cool. The 8080 and Z80 were fast for simple text. I used mine all the way thru law school and it gave me an edge over the other students. Wow, nostalgia.

I remember building several of these back when I was a computer science major at Sac State in the late seventies. We added an improvement to the S100 mother board to add termination resistors to each trace close to the ground end to suppress noise.

The Royal Mail thing reminds me a phone conversation I had with them. RM "You have been calling this office every Wednesday for last 5 months asking if there's anything for you" ME "Unless you leave a card or something, there is no way of knowing" RM "The postman leaves a card when no answer" ME "But you need to leave a card, otherwise I won't know" RM "The postman leaves a card when no answer" ME "Unless you actually LEAVE this card there's no way of knowing you've been" RM "The postman leaves a card....

This series should be released as a podcast. I like to listen to these while driving

Thanks for making this! You have to remember the computer on Wargames was probably upgraded to a Z80 if “David” was a real hacker :) ..and he probably got it cheap considering how outdated it was by 1984. Fun fact: The WOPR prop was an Apple II!

I built one of these High Nibble kits a couple of years ago. It sure plays a mean game of chess. The quality of the kit is outstanding, with incredible attention to detail and is only bettered by the quality of the emulation software. Be aware that the way the clear Perspex back panel is held in the metal cover can result in the Perspex cracking and breaking off around the nut fixings (ask me how I know?). The solution is to superglue the four mysterious white Perspex reinforcements shown in the top left of the video at 11:56 to the clear Perspex back around the nuts. The reinforcement with the one corner missing goes in the corner beside the ESP32. It's obvious when you try it :-)

Thanks for the fond memories. I actually have an IMSAI 8080 system that I built in 1977. One day I will look at refurbishing it (hasn't been powered up in about 40 years). I will probably want to clean up the silver-plated chip leads that have turned black as well as replace the ginormous electrolytic capacitors in the power supply.

Hey, One I know very little about. Although back in the mid-2000s, because of the movie Pirates of the Silicon Valley (which desperately needs a remake with history beyond 1999), I figured this or an Altair would probably be the first switch computer I ever got my hands on. Nope, PiDP-11. And I ended up playing with a PDP-1 simulator before that. 😅 12:00 Easier method of Surface Mount Soldering (which is my favourite BTW): Tack the corners, Loads of solder, don't worry if you make shorts, cover all pads and legs, everything completely coated now?, lay solder braid across all the joints on an edge, sweep your iron across the braid, raise the braid and be amazed at your factory looking SMD job, repeat across other edges. I used to hate Surface Mount Soldering until I saw one of Benjamin J. Heckendorn's tutorials on the subject. He made it extremely easy, and made me realise I was overcomplicating the job by trying to be too careful.

I don't know if it's the cadence, the accent or the Royal Mail rant, but this video has the best (and possibly longest) Alan Partridge impression I've ever heard. AAA++++ would watch again

If you get solder paste in one of those dispenser syringes it allows you to put both solder and flux on the pad before applying heat, so you don't have to mess around with solder wire. It kinda works with an iron but it leaves many of the solder balls unmelted and floating around and you have to wash them off with isopropyl. Works much better with hot air and/or a hotplate. If I'm being lazy I will put paste on the pads and then hit like 4 legs at once(on an SOIC-8) with a 6mm chisel solder tip. If you're going to use wire the most important thing is to get the half size wire! I don't know the exact measurement of it I think the normal wire like you have is 1mm and this stuff is like 0.5mm The technique I used before that was like yours, put some solder down on one of the pads, clean and put flux on it and one end of the component, then with tweezers and the iron attach the component to that one soldered pad. Then for the other pads, lay the end of the wire down in the joint you want to solder and hit it with the iron. This limits the amount of solder to just that which is in the joint initially and you don't have to try to feed in a tiny amount of wire from the side. At this point I dread through hole component much more because there's all the fiddling around with cutting the leads and they're a pain to clean all the burnt flux off of. Surface mount is quick and clean.

19:25 LGR would be drooling over the vintage woodgrain PC.

A small bit of Trivia... Cromemco got it name from a graduate student dormitory at Stanford University, Crothers Memorial Hall, as known colloquially as "Cro Men" and the founders lived there.

I played a similar version of Spacewar in the early 80s on the TRS-80 Mod. 1. Back at that time, it was fun, at least for me. 24:45

Awesome. The IMSAI 8080 is one of my dream computers, even though I have no idea what I'd actually do with it.

FUN fact. I ordered this exact same kit. and I politely asked the creator of the kit to solder the surface mount parts as I have a tremor in my hand, and he obliged :) Its in the mail right now :) some heroes don't need capes.

I absolutely must get my hands on this, the web interface is second to none!

I remember watching this movie in the theater. It was one the reasons I got into IT.

Great vid! Really interesting to me, as friends of my parents setup a computing shop in Epsom, Surrey, UK as an IMSAI dealership. They ploughed all of their savings into it and opened, after many teething problems. A week later IMSAI went bust… That was the end of that, really. They had to relocate to Yorkshire and start life over. I’m sure there are many other similarly sad tales.

I worked at Computerland when I was young in 1985. Fun times.

Even the "real" IMSAI 8080 and the "real" Altair 8800 still had fake front panels. Those CPU chips didn't have enough pins to directly have the front panel lights and switches connected. What happened was that the "front panel" actually consisted of a ROM chip with tiny programs that input/output the front panel switches/lights to the CPU via the regular input/output lines. Nothing like the original PDP-8 etc, - especially the PDP-12 which was a GORGEOUS thing! - where the front panel switches and lights were directly connected to the circuits.

Thank you very much for this. Always enjoy your content.

Absolutely elated to see a new video. Thank you.

11:09 I can relate to that, I sometimes get calls from delivery people where they say nothing on my answering machine, they apparently can't read my intercom listing for my name, input four digit codes, or leave notice they had been there. It's either that or I've been home all day and I get a message "they just missed me".😒 It's interesting to see what home computing was like for before PCs, in that era you really had to be dedicated to computing and search out materials intensely, kind of reminds me of the early days of video exports or playing Japanese games before emulation Ie. full time job to get a hold of anything.

The IMSAI 8080 and the Polymorphics 88 (Poly 88) were what I learned BASIC programming on. The IMSAI took a few entries on the paddle switches to get the monitor code running, before we could work on actual programming.

I actually used WordStar to write Z80 assembly language programs... around 45 years ago. Thanks for the trip back in memory alley.

Love your style and videos Keep it up.

Great video, I remember using supercalc 2 at home on my cpm machine. Takes me back.

You want to get some of that flux that Louis Rossmann uses. That shit's amazing! Makes light work of surface mount.

I've got an unbuilt AC-30 on the shelf - new in the box, still in the bags. It looks awesome!

Another beaut! Great video, I'll have a look for the kit.

As someone who built a Heathkit H8 in 7th grade (took a weekend), you just earned a like & sub. Don’t know how this ended up in my recommended video list, but thank you RU-vid!

Never thought I would see SMD inside an IMSAI! Imagine telling the creator that one day his machine would contain, and be emulated by a 32 bit microcontroller the size of a matchbox. Let alone - it has a web interface without the need of a modem! He would **not** have believed you. Great video BTW :-)

Our UYK-7 system could boot form reel-to-reel tape, which would then utilize Winchester disks, but we still had to manually enter the initialization code via the main console switches. I think I only had to do it once (technically twice because I screwed up the first attempt, which was common). Eventually I became the “micro computer guy” and never had to deal with that antiquated POS again. FYI: Troubleshooting the tape drives was a nightmare. I don’t think we ever had more than two of three functional at any given time.

They really should use a bitmap font to make that terminal feel a little more authentic.

what's the DE/WM/theme you were using when you opened the TTY app thing?

A friend of mine had an Altair. We had a lot of fun with it.

New subscriber: this is brilliant. I have one of these kits waiting for my 1 year to pass since I haven’t had time to build it. 😂. Love the channel

lol, surface mount is easier than through hole, it just takes a little practice with the right iron tip. A J tip is mandatory imo. It’s shocking how much difference it makes. PS great video, I have a High Nibble IMSAI 8080. It’s amazing.

I still have my old Altair. Haven't pulled it out in decades, but never getting rid of it =)

It's interesting, that in the War Games book it was Altair 8800 ...

You sir, have earned my like, subscribe, and comment. Good job.

Yes I know it’s a kit, but still 10/10 for patience and skill Sir! Regards from Brum! 👍🏼

What’s the song during the soldering montage? Really digging that bass player.

The easiest way to solder smd chips is to just solder 2 pins on opposite corners then drag the solder and iron across all pins it will bridge some thats ok then use solder wick and suck up the extra and the solder on bridged pins this method looks great and haven't ever had a bad solder joint

Used the original in college. Even had a floppy (8inch) with CP/M. Fun!

Mini computer Micro computer. Where are we now? Pico computer? Nano computer?

AGH THE MUSIC! Please change your background music loop. It drives me CRAZY!

My school had one of these when I was in year 11. And an Altair 8800. They were so precious that us students were not allowed to use them. Sad really.

"Assuming Royal Mail uses a postman and not a ninja" = LOL 😅🤣😂😆

My first computer was an IMSAI 8080, i bought in kit from from Byte Shop in June 1975, I had only 24K of RAM, and a few cards, one of which was a Cromemco Bytesaver 2708 eprom programmer in which I burned a copy of Processor Technology's BASIC, I had the Processor Tech VDM-1 video card and their cassette interface (1200 baud). I had to install a line choke on the AC line because my computer would reboot every time the refrigerator came on

I thought the two planes in ‘Dogfight’ were going to just fly into each other lol

Thank you very much for making an entertaining video.

I worked and even Ran the Company named UltraByte, back in 76 -78 and we sold over 2000 of these IMSAI 8080's. Even 20 to NASA. Basic was the simple language.

Royal Mail Ninja, thanks, that made my day !

Awesome video!

the way he says PCB WAY makes me chuckle haha

yooooo, War Games (1983) IS MY FAVORITVE MOVIE

When I was a kid, I strolled by the local electronics store to stare at the IMSAIs. ALTAIRs and SWTP computers of the day and imagine myself building my first S100 computer. It was probably fortunate that my first computer was an apple ][+; anything I built without any experience would likely have never worked.

If I didn’t know better I’d have said that montage tune was Jethro Tull

There's something quick to try that might fix the vertical hold sync issue on your vt220. Take the case off and look on the lower right or left side for two turn-pots. One is the vertical hold, and it's worth a try to turn it back and forth a few times to clean the contact. This might fix it..

Purchased my Apple IIe and Amiga 1000 from ComputerLand. That was a long time ago......

That’s so funny (or my cell phone is listening at me). I literally watched it yesterday evening again! After hunting for an IMSAI is the price. And even the kit is pricey but I may sway for that.

I played a little bit with the MCI when it came out at one of the computer shows I went to, but I went to Apple as soon as I could

Great Video!!

I had one of those. I bought mine in Nov. 1976.

Wanted one of these for a while. What was the royal mail ransom tax like on this?

I still have my IMSAI. It almost certainly needs new power supply caps :)

You mentioned the 4004. Well, I was disassembling a huge number of PC boards, and sorted the chips to be sold later. I had a number of chips I wasn't familiar with. Among them was an Intel 4040. I looked up the number, and couldn't believe what I had. I was a bit frustrated because I wanted to know what board it came from to see the support chips if any, and what it did. None the less, it is worth over $100.

OK, now I'm curious how much allowance a teenager in 1983 would have to have to afford all the components of his computer. The computer was sold 1975 to 1979, but there couldn't have been that much of a price decay, right? Even if we assume he got it used from someone picking up something new and fancy, it seems way out of his budget. Or did prices fall off that hard after everyone moved on?

It's like listening to Alan Partridge talking tech....

... well, I know what I am asking Santa for this year...

There's a thumb-wheel trimpot near the edge of the main board in a VT220 that, when it gets dirty over time, can cause that sort of vsync issue. You may just have to gently tweak it.

9:06 Black paper tape ... don’t recall having seen that before.

11:30 - One superiority US mail has over UK mail. We don't need a card, just our license to walk in and get our missed packages. No fuss, no muss, and if the town is small enough you don't need a license after the first visit.

Liked and subscribed!

I reemember programming one of these in z80 assejmbly with a 8 inch cp/m disk in tow...we used wordstar for our editor and had to remember to have to text mode or the assembler blew up. This was like 1987...so it was considered very dated for the university to be on such hardware...but I didn't mnd..I had learned z80 on my sinclair zx81...so I already knew that so it was easy.

I can not recall the last time I enjoyed a video so much that made me fee so stupid.

In the US, we pronounce it "sodder", or simply sod for short. "Are you going to sod those chips onto the board?" 🤣

Could some party win majority in parliament entirely on the platform of “we’ll make Royal Mail wait for you to come to the door”? Great video.

This is what we learned on in high school. Sometimes it worked.

Friend, where's your Patreon or youtube membership thing? I want to support your amazing videos.

I still have my original Imsai 8080. However, I built it with Z-80 processor board. Can't test it because I no longer have a compatible monitor or model 33 TTY. The 720K floppy drives and a couple of the switch handles are also missing. I should try and sell the thing I suppose.

We have to give credit where credit is due. 👍

It took a year for you to find the time to build your kit? Good to know; my kit has been sitting for only six months.

Careful running Zork, You are likely to be eaten by a Grue!

"MITS", not "MIT", for Micro Instrumentation and Telemetry Systems; they got their start making those two kinds of electronics for hobby rocketry and similar small missiles, then went into early calculator before producing the Altair 8800.

you are correct, she is a beaut

Ever think about tinning up the contact pads first, then using a heat gun to surface mount solder the components?

Nice! FWIW: Get a hot air rework station - it makes surface mount a breeze (pun intended). Louis Rossman sells them on his store for $160, and he has plenty of videos showing the technique. He would approve of your liberal use of flux 😅

@7:42 .. I guess she ended up marrying a less geeky guy :-)