The Computer that Birthed BASIC and led to Microsoft!
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- Опубліковано 28 вер 2024
- The Altair 8800 - Bill Gates - Microsoft BASIC - ...and the story that ties them together!
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Thanks to jonpaulmoen for preserving the source material for the Bill Gates sections!
For clarity, I'm talking specifically about MS-BASIC, not BASIC as a language. I don't want to rile up the Data General Nova users... they had BASIC beforehand.
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Good work Dave!! Looking forward to some future videos of you using the thing.
What a generous perspective for those that hadn't lived through the time. This article came out I was in middle school. My EE uncle bought a kit, but didn't get it working. It was later given to me, but thrown out while I was away at college (someone cleaning the garage! - I haven't tried replacing it.
I have to say I saw the title and hoped you would be talking about the PDP-10, it was here the Gates and Allen learned programming (a terminal at Lakeside) and their experience with that instruction set put them in the position once at Harvard to start working up their 8080 re-assembler and the Basic interpreter, without having to first learn TOPS10 and the DEC environment. Allen talked at some length about their development cycle in his book "Idea Man" (2011).
I think this doesn't get enough notice, the advantage of years programming and especially low level assembly from their teens positioned them to get straight into creating their Micro-soft product and be 'first to market'.
I was a Popular Electronics subscriber when that January 1975 issue arrived in my mailbox with that intriguing cover story. At the time my interest was focused on audio circuits, things like amplifiers, mixers, etc. -- and this issue prompted me to get interested in the possibility of owning and using my own computer. WOW! A Personal Computer! Years would pass before I finally had a computer on my desk, but that was the beginning of my software development career.
I guess you were really interested in how to read FM Turner specs then, I got into the computer field in the same way, here in Australia we had "Electronics Australia" I built the Signetics 2650 Kit what was June 1978 EA project.
Pretty much the same story and eventual career path. I saw the Mark-8, Altair and IMSAI computers in the magazines of the time and dreamt of the possibilities. Eventually, I bought a Netronics ELF II kit from a school friend who lost interest in it and I got my first experience programming computers using the CDP1802 instruction set. I still tinker with my CDP1802 based computer systems and I often resort to lessons learned programming the 1802 when coming up with solutions for writing software for current projects.
This man is slowly but surely building his own computer museum. Golden content, Dave!
Built my Altair 8800 from MITS as a Kit of the month plan. Each month you got a part. Last part was the Intel 8080 processor. It worked the first time. Toggled in kill the bit as my first program. Got a serial board and hooked it to my "TV Typewriter" terminal that I built the year before. Later got cassette tape interface working. Sold it a few years later and built a Altair 8800B. Those were fun days!
I was a college freshman when that magazine came out. Despite the excitement, I was scraping by just paying for school and the Altair 8800 was hilariously expensive for what you got and unattainable for me at the time in any event. If it wasn't for competition by the 6502 shortly afterward I hate to think how long PCs would have remained expensive luxury items. I don't think Intel or Motorola ever intended to address personal computing.
Minicomputers occupied a role smaller than mainframes and microcomputers would be the next step down in this continuum. But the target audience was still medium to large businesses who could afford to pay 4+ figures for a microcomputer rather than 5+ for a mini or 6+ for a mainframe. The people who formed MOS and Zilog figured this out and left Motorola and Intel, respectively, to create the personal computer revolution themselves.
It was summer time at university in the early '70s and I was sitting in the sun on the lawn doing some reading when a fellow postgrad came rushing over with a magazine advert. "Look you can actually buy a computer for less than the price of a family house! Personal computers have arrived." The machine advertised was a DEC PDP8 with 4096 12-bit words of memory.
Motorola rejected employee Chuck Peddle's proposal to create a low cost stripped down 8 bit microprocessor. Chuck recruited some colleagues and together they created M.O.S. (M-O-S not MOSS) in Norristown, Pennsylvania. This came roughly at the time that the American calculator manufacturing industry began to wither on the vine. Market maturity and commoditization possibly aggravated by T.I.'s alleged attempt to compete with the Japanese suppliers by sucking the remaining profit out of the calculator industry by undercutting its supply chain buyers. Meanwhile, Auschwitz survivor Jack Tramiel, had transformed a small typewriter repair shop in New York into a successful calculator and office equipment manufacturer in Toronto called Commodore Business Machines. Commodore's biggest supplier of calculator IC's was Texas Instruments. Jack was outraged that his primary supplier, TI, in an arguably shortsighted and self serving move, would undercut the profit of their long trusted supply chain partners by selling the chips to their own calculator division at a large discount. This was a market that Commodore had worked hard to shape and grow over the years. Dismissing Commodore's interests was a major gaff that would later hurt Texas Instruments in a profoundly negative financial way. Tramiel's outrage at the alleged unethical squeezing of Commodore's supply chain would take years to forget, if ever. Jack's aversion to the feeling of being taken advantage of, coupled with an instinct for survival led to the purchase of MOS Technology, a cash starved semi conductor design and fabrication company. MOS would give Commodore the ability to create their next big thing in house: The Commodore PET. A computer that would be simple and affordable. A personal computer for the masses, not than the classes. I digress.
Did anyone else notice that the Altair shown in the Gates footage is a replica???
How do we know?
I wouldn't know the difference, but I might recognize it if it was the IMSAI ;0)
I didnt notice, but i was looking at this recently and found an emulator/simulator of the altair 8800. You can see some how to videos on how to use it in youtube as well. Pretty fun
They probably couldn't afford an original 😁
Not me… my first computer filled a large room.
My father was a computer scientist at Georgia Tech. He would take me and my brother into his office when he worked late.
I use to play the lunar lander program as a game… long before there was such a thing as a computer game, even before pong.
Working on c.1990 CNC machines, we'd start getting memory and bus errors randomly. A common troubleshooting procedure included removing the memory boards, taking them to a mop station, hosing them down with hot water and floor degreaser. We'd rinse them off, blow them dry-ish with compressed air, then let them air out until the next day. It was startlingly effective, and I don't know of killing a single board that way.
Well, the only real danger is leaving behind conductive liquid(tap water) that might short pins when dried(less of a problem with large dips) - or the always present danger when handling old boards: static.
My favorite mixture is still demineralized water+isopropyl alcohol in an ultrasonic cleaner with a drop of fabric softener for the anti static properties - saved quite a lot of toilet iPhone logic boards that way. And the fabric softener also makes them smell less like toilet.
Former Sony Engineer here.
Electrolytic capacitors (e-caps) has a lifespan of about 6~12 years (you can read that in more details in any e-cap datasheet), after that, it start to degrade. Since your computer is from the 70's, your computer need a full electrolytic capacitor replacement (recap) before start to operate full time. E-caps are made of an electrolyte and *water,* since you water your board (not recommended) that might did something to make it work but it will eventually fail again if you don't address this issue right away.
We don't clean PCB with water because when the water or when the PCB are in a high humidity environment, the moisture expand. When it get into the layers of the fiber board or under the copper of the tracks and expand, it creates bubbles.
Good luck.
As with the Commodore, oxidization is the number one thing to check for on this old kit, so a good clean of the connections is a great place to start.
Would love to see you recreate the first time Alan got Basic running on the Altair when he flew out to New Mexico. From entering in the boot loader to reading in the tape to actually performing validation checks to show it actually worked.
I'm impressed that you lined all the screw slots in the same orientation. I used to work in assembly at Allen-Bradley/Rockwell Automation (building CNC control computers) and we didn't care how the screw slots were oriented as long as the screws were present and properly tightened. That was our level of precision for screws. As you could imagine, it was far more important to get working machines out the door and into customers hands.
Good on you for taking the time to get the old Altair back on its feet.
…The video was an 8.9, then I saw the alignment of the screws in the back. Instant 9.4!
Either way a thumbs up from me.
Thank You again Dave.
I miss hardware! I first got into computers in 1996 when the 486 was being phased out for the Pentium, but I got to work on a lot of older systems using MFM and RLL drives and how to manually setup HDs using CHS. Good old days of computing.
what was that command again? Open debug and enter g800?
@@javabeanz8549 g=c800:5
@@thejoneseys that sounds like the standard one, there was another one for some controller cards, but it's only been about 30 years since I moved over to IDE (PATA in newer terms)
Using your resources to show off such great piece kit that the vast majority will never get their hands on is such a great thing to do. Absolutely fantastic stuff.
I cut my teeth in MS BASIC, but the only thing I remember these days is shift and run/stop, then typically after about 5-10 on the tape counter, press the Commodore key when the file name appears.
Back about 1973, my employer bought a Data General minicomputer. Usually, booting up one of these required entering a bootstrap of about 23 words using switches as you described, but we had the latest version with an extra chipmwith the bootstrap encoded.
Hi Dave. Take it from a guy who has been working on a Raspberry PI based brain for a DIY smart still for a couple years. Distilled water isn't conductive. No electrolytes, no conductivity. I learned this when I first approached the idea of detecting the level of alcohol in the distillate. I already knew that ethanol wasn't conductive and figured water in the distillate would indicate that there was no more ethanol to extract. Nope, distilled water has no electrolytes, not conductive at all. So, distilled water is perfectly safe for washing down circuit boards with.
Is the water still non-conductive when it dissolves metal salts and oxides from the corroded parts?
@@katbryce ohh, memories of Chemistry lab 40 years ago. Psyche!
@@katbryce Equally as conductive as any other liquid that you would use for the same purpose.
Beautiful, just beautiful. Always wanted one of those. Read the original article when it came out and knew immediately my future profession was going to revolve around computers. Now my home office is jam-packed with computers, both ancient and (nearly) new! Glad to see you enjoying it so much. Keep up the good work!!
I'm 43 years old, I only got in to this back in the days of 386 and BBS days which at that time was right at the key to our internet. I was fortunate to be part of that transition. So cool to chat with MS guy from that time :P Thanks Dave for sharing your skill and taking the time to make some very fun and informative videos!
Fellow Xennial. We were so fortunate to go from "functional" personal computing to the web by the dawn of the new millennium. We have roots in "analogue" but took flight in "digital".
8:27 that is basically how it works today, there isn't anything on a graphics card, or motherboard for that matter, that runs on 12V other than the regulators that make the much lower voltages for ICs and IOs. Distributing something like 1.2V at hundreds of amps would be very inefficent and basically impossible
I started using BASIC -- specifically DEC's EduSystem BASIC -- in 1973. We had a half-dozen ASR-33 teletypes as interfaces into a DEC PDP-8, 3 of them connected remotely via telephone modems, and we saved our programs on punched paper tape. Each terminal was allocated 4k of RAM. My, how things have changed.
I remember when that magazine came out. I was programming IBM mainframes in assembly language at the time and I knew it was a big deal. I still have that magazine issue locked away all these years later. Gates and company built an empire and I have a magazine put away - yeah, missed that opportunity.
If you wanna get an idea of how much water electronics can handle (while powered off of course), well I entered into the electronics repair field right after hurricane Katrina.
My late father had picked up an entire truckload of completely flooded computers and brought them to me asking if I could fix them.
My heart sunk and I gave him the crazy eye like WTF you expect me to do with all this sh!t? But then after about an hour of brainstorming on it, I was like what the hell, why not try something at least? I mean hell, it was all a loss already, not like I could really hurt anything ya know.
So I went to my nerd friend's house who happened to have a pressure washer, and asked if I could borrow it for a bit. Of course he looked at me like I was stupid, to which I agreed with him LOL! And then I went out to his back yard and proceeded to do the insane...
After I pressure washed the few boards, I set them all out in the sun to dry for the rest of the day. By that evening I knew it wasn't gonna dry anymore than it was since the dew was starting to set, so I picked what seemed to be the highest spec board and brought it in his place to test.
Sure enough the damn thing booted to BIOS! I ran out back where my buddy was burning hurricane debris in a bonfire, ecstatic to tell him the good news! He came right away to see this former hunk of mud booted up, and it was still displaying the BIOS screen, but it had locked up.. ☹️
Well, we figured it probably just needed a bit more drying time, so we shut it down and gave it another full day of drying time, and after that it ended up working perfectly! That ended up being a huge upgrade for me too!
I salvaged quite a bit of that haul too, and as I continued this crazy pressure washing venture, I added a step to the process by using an air compressor to rapidly accelerate the drying time. Boy that sure helped a lot ya know...
A little thing I unfortunately discovered during all this though, is that any which way I went about it, its not a good idea to pressure wash power supplies LOL! They pretty much all let out the smoke ya know, but the boards were pretty much all perfectly happy with this.
Anyways, thank you for coming to my Ted Talk.
the psus would likely have survived and been ok but you wouldve had to be absolutely sure they were completely dried inside,
@@andygozzo72 Indeed, you're likely right, but at the same time I believe some of the remaining water had infiltrated and saturated between the coil windings in the transformer and inductors. And given that they had been flooded in brackish muddy water, I think it had already compromised the insulation of the windings prior to ever trying to clean them. So unfortunately I don't think it would have really mattered much how long I let them dry, I think they were already compromised no matter what I did.
@@southernflatland : Likely true, though I have to say that using a pressure washer seems a bit extreme. I would have probably just used an ordinary hose.
Last step after "washing" power supplies; isopropyl alcohol bath. Full submerge. Displaces the water trapped in the nooks and crannies.
@@eljuano28 Sounds like an awesome plan, should I ever have a reason to try it again anyways.
I'm sure I wouldn't have been able to come up with that much alcohol right after the storm though, we were half without electricity and struggling for food, clean water and fuel for vehicles and equipment after the storm.
With supply chain difficulties and all, there's only so long before you can manage to salvage these sorts of things before they corrode too much to be saved.
In my experience doing this, I managed to save about 80% of the boards I washed within two weeks after being flooded. I even salvaged a few hard drives, but I had to recover the data quickly to known good drives as there's no chance in a flooded hard drive to maintain a seal in the long run after being flooded.
Edit: After about two weeks, the boards had generally corroded too much where pressure washing alone wouldn't work.
I also ended up upgrading the first experimental board there with another flood salvage board, after I replaced 14 capacitors as well...
This took me back to the early 80's when I got my hands on an already old 2650 processor and board to build. Fun times.
That trs80 brought back memories! I remember using turtle to draw things back in 84 and the slowly learning basic in 86-88
What a treat to watch this video, I love seeing this old 'stuff' getting reanimated as well as getting some well deserved love and attention from its new owner :) Thanks for the video Dave, keep it up!
At 12:57 “…screws all nicely aligned…” phew! Sooooo nice for OCD, thanks for the great video!
I worked for a company in 1977 -78 that had exclusive to sell IMSAI 8080's - essentially the same as the Altair ad I think made by former Altair employees. One summer at Ultra Byte I sold over 150 of them , 20 to NASA - they claimed to be using for "mail system" but a couple years later I saw them in mission control consoles.
My dad was an installer for Western Electric, working on the first generations of ESS. One day he came into my room, all excited, and threw that copy of Populatr Electronics on my bed and told me the computer age was starting. Within 5 years he bought an Apple II+, serial number in the 2000's. He had to lie to my mom about the cost, but both me and my brother used the hell out of that thing and have had careers in tech. So worth the cost, I think.
My start was a little newer in the Apple II+ but it lead me down a 30 year path in computer tech.
My father saved and purchased an 8800. I remember it came in large boxes. One every few weeks until we had the whole thing. I was only about 11 or 12 years old but after a bit my father had me soldering components to the pcbs. I wasn't allowed to power anything on until he checked the board assembly. While I don't recall a lot of what we did with the Altair, I do remember the joy and excitement when we got a Lissajous pattern on the oscilloscope. I do remember hand assembling short programs and entering them by hand. I know data added a couple cards to the Altair of his own hardware. His interest was more in electronics than programming and I wrote most of the code for the Altair. We didn't have a terminal so we build a keyboard on a piece of wood paneling with a few dozen little red Radio Shack push buttons. The letter each button represented was mark on the board above the switch. Later my mother wrote tiny little stick on labels for each button. White paper labels with blue ink that eventually smeared and wore off. Eventually, my father started a TV teletype writer to use as a terminal, and got his hands on a paper tape machine. I don't think he ever got the paper tape to work and I'm not sure he ever completed the tv typewriter. But that Altair gave me my love of coding and electronics even though I only used it a couple years before the Coco and Commodores became the thing, these too seemed short lived and were replaced by a Tandy 1000. My coding skills went from 8080 machine language, to BASIC, to Pascal, Forth, C, and C++. Today, I do things mostly in Python and C, and occasionally in Dart and JavaScript. Though of late I played a bit with Algol, FORTRAN, and Pascal just for kicks. There is still a lot one can learn from revisiting old hardware and old programming languages. If nothing else, I believe every developer should have to write an animated side scroller on one of these old systems as doing so requires a good understanding of the hardware, software, and the limitations of the system. This like many of your videos has brought back some fond memories. Thank you!
Dave, this was pretty neat to hear the history and your detailed cleanup - especially the cleanup. Thank you as always for your videos!
I have a few "portable" PCs from the mid 80s which my dad first introduced me to, BasicA programming. As you can imagine, as a 5yr old I was more excited to make it print funny words. But it sparked my journey to become an engineer.
Washing down a computer brings back memories of my industrial electronics work. Yes, water wash is no problem (with any batteries removed), something I often did to contaminated PCBs. The key is thorough drying. Half an hour in an oven set very low, or overnight in the airing cupboard generally sorted it. Water only hurts electronics if it is under bias and electrolytic corrosion goes on. But flood water leaves muddy residues that can be hygroscopic and can conduct, so a clean wash-down is important.
The most memorable occasion was the SMPS from a toffee wrapping machine. The filter-less fan had ingested sugar mist for years until the whole PCB was covered in a layer of toffee. A good soak in the bath and thorough drying and it was good as new.
Yea, I remember the Altair basic. Microsoft had a 4K, 8K and a 12K version of the basic. Back in the days i did a disassembly of the 12K basic so I could port it to CP/M. Had to undo a lot of smart tricks that was in the code to make it assemble and run under CP/M.
One of the really neat codes in the 12K version was the routine to check for variable type. The 12K basic supported integer, string, float and double. The size of the variables were 2, 3, 4 and 8 bytes respective. It does a compare of size with 8 and then three decrements and after this the flags is set as follows: Minus set if integer, Zero set if string, Parity set if float, Carry cleared if double.
Glad you took the appropriate safety precautions (checking wife was out)
Looks like some of the PSU electrolytic capacitors have already been replaced - might be worth replacing them all TBH or at least checking to see if any are bulging - they don't age well compared to the other components.
I noticed the two different capacitors but then figured they were probably different voltage for the other rails. 1970s electrolytic capacitors are pretty reliable.
Do I ever remember. Unboxing the Altair 8800. I had a teletype hooked up. Loaded up BASIC. Before long I figured how to store data on a cassette tape and wrote a transfer program to copy BASIC from paper tape to cassette and wrote a new boot loader to read programs directly from the cassette. Those were the days.
I was exposed to the Altair 8800 as at the age of 13 years old. I was on the way to work for the summer with a relative in Ontario. While in transit I stayed at another relative for a week and he had a Altair 8800. I was given the task of labeling the keyboard keys with their new functions after he had gotten a OS upgrade that supported a floppy drive. The number on rule was do not turn it off. The Altair did not know how to access to anything on boot so you had to program to boot code via the front switch, Which i was told was a very long a tedious process. That week opened a whole new world to me.
I had a friend in the late 80's earl 90's who bought computers from estate stales. i loved checking out how this stuff worked. Loved it.
I always had a fascination with the mechanical side of PCs more over than the programming side but I love both of them just the same. Just wish it was easier to understand
A good friend of mine was working with Ed Roberts at MITS when the Altair 8800 was being developed. He was working there when Bill Gates and Paul Allen came down to develop the drivers to get their BASIC Interpreter working on the 8800. MITS was started as electronic hobbyist company selling tracking RF Transmitters for hobby rocket makers. With the on-board transmitter a hobbyist could find his rocket after its flight by using a directional antenna to locate the transmitter signal. The hobby missile electronics people didn't think the 8800 would be successful so they split off from the company before the Altair became popular.
For me, this has been the most interesting video so far (and I really enjoyed many of the others) - thanks very much for making and sharing!
BASIC was developed at Dartmouth and emerged during the 60's, It first ran in 1964. During the early 80's before the IBM PC basic was around. It ran on many of the machines before the IBM PC on Intel 8080's and Apple early machines. The transferall across machines was widespread, with Kurtz (one of the authors) working on it on several machines.
I bet shipping jostled the wire lose. Nice job. You'll be mining bitcoin in no time.
I built mine in 1975. It launched this college dropout from file clerk to systems analyst in a couple years. Thanks for the memories.
Excellent, thank you. Though the first computer I unscrewed was an IBM PC, it all looks very familiar and I remember coding 8080. Nostalgia!
I wasn't even born when most of the tech you show was made but I love seeing the origins of it all
Uncle Dave, this linear power supply rely on the load from the different boards to bring down the voltage of transformer secondary winding.
I started learning electronics in 1976...
Flow goes like so:
> On/Off Switch
> Primary Fuse!
> AC Transformer 120/07VAC
> AC Rectifier diodes in bridge
> DC Filtering Capacitors
> Secondary fuses!
> Dispatched to daughter boards for local regulation.
The voltage regulator is where the most heat dissipation occurs.
TO3 were used.
Caps advice if you will:
2 light Blue caps seems to have been replaced. These parts are known to age and are very cost effective. Change the whole supply board cap collection for $1Ea.
Keep the same caps voltage but bump up the uF to get smoother filtering.
"Low ESR Caps" not necessary here but nice upgrade as well.
Repete filtering upgrade after each local regulation circuits.
You absolutely need clean DC Power to feed digital TTL gates, right?
C-MOS chips were right around the corner... MIL Specs
👍
One thing's for certain, the smoke hasn't been let out. Yet. Thanks for the amazing and engaging content.
Edward Robert's was my great uncle! He invented the Altair, GATES worked for him during that time, then he sold it! Thank you for showcasing his work! I don't have one of these!
Mits was sold to a company called Pertec. They made tape drives. Pertec thought they had bought ownership of the software. Bill Gates father was a lawyer so they knew to sue to regain control of the software. Thus Microsoft was born and the could sell it to Tandy, IBM, et al.
I bought the Altair kit, and received a notification from MITS stating that it would be delayed due to them designing a bus interconnection system instead of the point to point wiring system.
Dust/dirt. Once had a Bunker Ramo BCS 90 that was literally full of dust. Took it outside and used a vacuum/blower. It ran correctly when I powered it up.
The “IT” manager had the unit on the floor and was surprised at the dust accumulation.
I was planning on getting an Altair 8800 since they first came out but when Radio Shack announced the TRS-80 model 1 with keyboard, monitor, and tape storage, I opted for that instead.
The first 8080 computer I saw was when I was working at a high voltage power supply company and the guy sitting next to me brought in his new Heathkit H8. He flipped a few switches and made the LED's blink. I bought a HP-41C calculator.
I was never a coder and I could never play one on TV. ;-)
Wow you brought back memories. I got my first computer in the early 1980's a Commodore 64 and self taught myself to code in BASIC. Using a tape drive I wrote my first program that kept track of our farm production. I even repaired my 64 when a circuit went bad and I had to resolder one of the traces to get it working again. While I don't have my original 64 I did acquire another brand new still in the box 64 I keep as a reminder of my start in computing. I also still have my original 128 and omega. I never did make a career out of computing but use them every day. I tried learning other languages and did code simple things but never mastered any of them. Python was the last language I tried with some success. I lost count of how many computers I owed over the years Apple and PC now with a custom Falcon Northwest running windows 10. I am currently learning Electronics and have a small lab in my basement doing electronic repairs. I stumbled onto your UA-cam channel when I was looking up info on LED's. Great channel I have subscribed ty.
My first computer experience were two books that had BASIC programs (of mostly computer games) printed in them. I would study the programs trying to run them in my head. I remember one of the games was about catching (or avoiding?) a Wumpus. Occasionally I went to an electronics store in downtown which had a computers dept in the basement. They had home computers like the ZX Spectrum, C64 - and in the "pro" room behind a glass wall - also IBM PCs, Commodore PC clones and also an Atari ST and Amiga 2000 (which I ended up getting for Christmas).
In 1976, our teacher had a 4004 from SouthWest Texas Technical Products Corporation. It held 4kB of RAM. It was about the size of a car radio, with DIP switches on the front panel for input. The only other input was a standard shoebox casette tape recorder. It took over 20 minutes to load a little character-based StarTrek game! The manual was a good-sized book, but we had a blast with that thing. Programming was an electronics wonk's game back then.
A few years later I was coding on an IBM 020 keypunch desk, and setting RPG programs on plugboards. The good old days!
Nice trip down memory lane but US focused. The first home "computers" in the UK (we were not able throw as much money at this stuff) included the Sinclair SC/MP.. a computer with no stack. Nearly put me off computing for life. The Z80-based Nascom 1 restored my faith and I eventually expanded into a full, boxed PC.
I believe the term you are looking for when what you're working on suddenly starts working for no apparent reason is PFM, or at least that's what we called it down at the Johnson Space Center in the early 70s. BTW never heard of a PDP 10. We had some PDP 8s and PDP 11s. Enjoyed the video, thanks
I remember visiting the Heathkit store with a friend. We saw the Altair computer there.
I like Robert Cringely's description of the Altair 8800 (in his Triumph Of The Nerds documentary) when it first came out as "a solution in search of a problem". I think he nailed it IMHO.
11:40 "I honestly don't know how much water electronics are capable of temporary tolerating..."
A whole lot. Assuming you've removed the power source and discharged any capacitors before the water happens, and you dry it all out before it has a chance to cause any corrosion, it's actually pretty hard to destroy electronics with water alone.
Built s/n 14 in our dorm with a few friends. Ah, those were the days ! Ended up building a ton of cards and parts, and eventually had it interfaced to a beehive terminal.
An Altair 8800 very similar to that one was gifted to teenage me in the 80's as it was already obsolete. I messed around with entering simple assembly language programs into it for a couple of months, but ultimately decided to scrap it. I still have the front panel switches, transformers, and fans. As a teen, it was hard to imagine it becoming collectable given the onslaught of much more interesting machines.
This is a very common result in troubleshooting electronics. "Not sure what I did, but it's working now..." That said, my experience is First, it's dirty. Second, "It's always the connectors." Not really, but these are always the most likely suspects. It's consistent with the failure pattern you noted, and with the fix. No power from the transformer = no power from the rectifier. If the transistor wiring was open, you would have been missing only the +5v, with no effect on the 8v.
Good job, Dave, and welcome to the magic of electronics. I always wanted an Altair, ever since they were advertised in the backs og the geek magazines I subscribed to. Congratulations!
Great video, Dave.
Your channel is as fantastic as you are.
Kudos, brother!
Darn, seems I'm already subscribed. Thank you for sharing your adventure into antique small iron Dave.
I really wish I could be around during when tech was growing like this. Physically flipping switches feels so tedious compared to the luxuries of today. Getting to see all of that evolve is something I wish I could see myself.
I'd like to hear what you think of the new UI with task manager. Seeing how it's still your code under the hood what do you think of UI refreshes in general?
Hi Dave. I'm in the UK. My first microcomputer I built from a kit. It used Nat Semi’s SC/MP (SCAMP) microprocessor. It had a simple instruction set and like the later Altair, there was no assembler so we had to manually enter the opcodes to create a program. Around that time, S-50 bus PC’s appeared and then the S-100 bus, as in the Altair 8800. Bill Gates’ anecdote about demonstrating their DOS to IBM relates how he realised they didn’t have a boot loader - so in the demo, they had to write a boot loader and then switch in the opcodes for it, all in front of the client. I went on to work on a product that incorporated the LSI-11, DEC’s microcomputer version of the PDP-11. It ran the RT-11 DOS which was way ahead of CP/M (and IBM DOS). I bought a home Z80 board with MS BASIC in an EPROM and a friend disassembled this. We were all astonished to see that the interpreter used every single byte in the EPROM. Someone, presumably Gates, had hand-optimised the code in order to save space. For example, there was a three-byte jump instruction in part of the code, but another part of the code jumped to the second byte of this, which then performed a different task! Great channel, thanks!😊
Still got mine in the back room. I had to install a power supply with more oomph in order to support all the boards I eventually plugged into it. Also replaced the processor board with a Z80.
well done, thanks for your contributions to the buisness. i recently aquired my AA in computer science and am looking forward to revisiting an Commadore 64 , sitting in my garage after a few decades! it is at least protected in a box, but it is old, i want to see how it will run , soon. thanks for your videos.
Thanks for the trip down memory lane! Computers were so much fun back in those early days. Kids today have things like Raspberry Pi to play with, but building a machine from a kit and having it actually work was a thrill beyond words. Hope all those machines wind up in a museum someday for people to ogle over.
Oh, I remember these. I had a Cromemco III myself. Digital Research CP/M on 8" media. S-100 systems were all the rage back then ;)
I started USAF Basic training in Nov 1974 and then on to electronics school at Lowry AFB in Denver. I started a subscription to Popular Electronics with my new found "wealth" and the first issue I received was Jan 1975 with the Altair on the cover. I was hooked. It would still be several years before I got my first computer, a Radio Shack Model I in 1980. Hope to see more of this beast as the first one I saw was in 1977 out in a computer shop in Albuquerque. Some of the guys were trying to get code running to access an 8 inch disc drive.
I "helped" my Dad build an Altair 8800 when I was a Kid, he still has it all these years later. It's why I'm a computer scientist versus following in my Dad's footsteps as an Electrical Engineer- I was fascinated with the possibilities. Eventually we had a CPM system then DOS and I actually learned to program on "Altair BASIC" as a 10 or 11 year old, to eventually work for MSFT 17 years.
When you applied for a job at MSFT, did you mention your prior experience in building an Altair 8800?
@@Martinit0 it was so long ago I don't specifically remember- but I bet I did !
The Dragon 32/64 played a huge role on that computer I started development of TCP-AI and later the Acorn BBC on that computer I developed OO
Interesting video - I love these history lessons, with actual hardware! A quick point on your analogy with sending unregulated power to the cards being as if modern PCs sent a single voltage to the graphics card and the card converts it to what it needs: actually they do - GPUs and their memory run on very low voltages (~1V). They pull power from 12V (via the slot and cables) and contain lots of voltage regulators (VRMs) to do the conversion. VRMs and their passive support components make up about half the components on modern graphics cards!
When I was a kid I remember that my dad had a computer like this one. I thought he called it a "S100 computer". I think it was called that because the cards had 100 pins or slots on the motherboard
Yep. I've read several incompatible descriptions of what some of those pins do, as well. Something about 8-bit vs 16-bit machines as I recall.
S100 bus
Great episode! I programmed in FOCAL [Formulating Online Calculations in Algebraic Language] in high school ('70-'73) on our PDP-8/S [S for Slow]. I toggled in the bootsrap and read in the paper tape OS, then the FOCAL. Bill Gates may have developed PC BASIC, but I must remark Professor John G. Kemeny, at Dartmouth College, co-invented and introduced BASIC [Beginners' All-purpose Symbolic Instruction Code] in 1964. D'77
Great video Dave!
I know it's back together now, but I would consider changing all of those electrolytic capacitors.
Having AC ripple on the supply could cause some interesting problems.
Great work Dave! Been following since the early days and love this old tech videos. Looking forward to see you running MS Basic in that awesome Altair! By the way I also follow your other channel since my daughter also lives in the Spectrum it has been very close to my heart
Experienced electronics tech here. From pausing your video at the circuit diagram and seeing the number of taps on the transformers, I suspect that the large transformer was for the high amp 8 volt feed and the smaller one for the other for your front panel, the multi-tapped smaller transformer would make sense for the + & - 16 volts. If this is the case the connections in the circuits to the smaller transformer would most likely be the cause of no 8V for your front panel, the act of simply pulling it apart, cleaning it and reassemble has rectified the connection issue. It is my experience that connections cause the majority of faults in circuits.
This is the original type of computer, flashing lights and switches. A superb teaching and learning aid because it takes you through the evolution of computers. I'm assuming you add a serial port and storage and end up with a normal computer you can type on.
One old trick from the days of gold edge connectors. Make a couple of passes with a Pink Pearl pencil eraser. Clean with dry brush and reinsert into edge connector. FYI.
I actually owned an Altair 8800. Wozzy wrote a small OS that worked well. THOSE were the DAYS!!!
Nice one, Dave! FYI, the serial board is likely to require +8V and -8V, as the RS-232 standard needs those. Next-generation circuits use ST-232 or equivalent level shifter chips that internally convert +5V to +/-8V for correct signal levels.
That 4K Basic was an amazing piece of work!
The benchmark of the day was...
FOR I=1 TO 1000
NEXT I
I took 4 seconds on the stock 8080.
The 4K interpreter took up about 3200 bytes of 4096.
A 32bit floating point subroutine package with transcendentals took about 1600 bytes.
That means they implemented the rest of the interpreter in 1600 bytes. That is really tight coding!
Mits came out with the Altair 680b that used a 6800 CPU. It ran at half the speed the stock 6800 could run at.
At full speed CPU it would do the benchmark in 3.2 seconds.
The 6800 was faster than the 8080.
Allen and Gates had implemented a 4K interpreter for the 6800.
Perfect openinggg...
D'oh!!!!
Another good vid. Thanks. For old electronics repair I recommend Mr. Carlsons Lab.
Wow. Fantastic video. I am a computer history addict , so I really appreciate these videos on vintage PCs.
Your bright idea bit was the alcohol wash and air hose.
Nice one, Dave! I immediately took offense with the title because I knew the PDP-10 technically “birthed” Microsoft BASIC - and of course not BASIC itself either but just the implementation. But yeah, I know it’s not easy with the titles!
But never mind the title - I really like the work! With old electronics a good re-assembly really is the equivalent of turning it off and on again. Good job with the restoration! (Coming in a video soon, I hope: “changing capacitors on an Altair 8800”)
I saw a documentary not long ago about Dartmouth Basic. One of it's creators mentioned that they did it "... in the year 1964 BG... Before Gates!" Hahaha loved that.
Awesome Score! Real quick, I suggest replacing ALL those old electrolytic caps.
The issue was the screw slots not being aligned. You fixed it when you reinstalled them nice and straight.
Yes, but how about an Ithaca Intersystems S-100 multiuser system running Coherent Unix and Z80's? Maybe a Z80H?
They were beautifully crafted machines and were on NY State contact at the time with excellent prices, but my organization went with Radio Shack Model II's.
At the time they pulled me in from my position because I was the only one who knew anything about computers! Anyone remember these days? They were quite magical. (reminiscing)
They ran Radio Shack's OS called TRS-DOS and for CP/M we use Pickles and Trout! 8 inch floppy's and a 8.4 MB hard disk. Advanced 300 baud modem.
Not a bad selection of business software between the 2 OS's at the time and could still run a small business very well today.
I still have my copy of the January 1975 issue of Popular Electronics. I also have an original cassette tape with ALTAIR BASIC 4.0 on it from 1977. No idea how I wound up with it as I've never owned an Altair 8800 or IMSAI 8080 machine. A few years ago I saw a working Altair 8800 that came with an extra memory module board that wasn't working. I was partly tempted to buy it but the seller was asking $4,000. I wasn't willing to spend that much on the system. I have considered buying and building one of the modern replica kits.
Nice video , i started with cmb64 in 1981 and it took hole nights to get the basic progs ready and running but it was big fun when it did work and turn the lights and motors on and off , now using arduino
Great! Congrats, and thank you for making the video.
Cool video, happy Christmas!
Pretty fair odds that you had something knocked loose in shipping and reseating it resolved the issue, also pretty fair odds that you had an oxidation layer that was resolved by reseating a component as well.
We use to have old benches that we had to run 24/7 else the compnents in them would oxidize and we would have to reseat all the cards and chips. Talking about a sucky weekend.
As noted in some other comments, the electrolytic capacitors on the supply board should be replaced. They do dry out over time. They are inexpensive and readily available and look to be easily accessible on the board for easy removal and replacement.
I recently replaced all the electrolytic capacitors on my 1980 Kenwood TS-830s amateur radio, which was over 100 capacitors and took a while, but slow and steady work finished the task over a weekend.
My first computer was an Ohio Scientific Superboard II. One of the guys I was stationed with in the Army in at a satcom station in Daegu Korea in 1978 had assembled his own computer from Ohio Scientific from scratch, including soldering in many of the IC chips on the various boards. Hi Mike if you're out there . . .
We spent quite a bit of time playing on that and learning and writing programs in 6502 assembler and BASIC. By the time I was ready to purchase a computer myself sometime around late 1978 or early 1979, they had released the Superboard II computer which was mostly ready to go, just needed a TV and cassette player for saving and uploading programs.
Great starter computer and first of many many more in the 40+ years since then.