Getting the Bendix G15 Drum Memory from System Source Museum

[@TechTimeTraveller]

Thanks so much for the shout out! I had this big surge of views snd subscribers this morning and couldn't figure it out until I watched this video! I am a total goof though compared to the stuff you do. Every video where you're doing a repair I'm learning something in a way that was impenetrable to me before!

[@UsagiElectric]

Thanks for highlighting so many awesome systems I'd never heard about before! Glad to hear we got some cross-pollination going on between our groups!

[@Pickelhaube808]

After both drums are back up and working, the next step is to put them in RAID 0 😎

[@dynad00d15]

sure.. nothing spells risk free like a RAID0 with hard drives dating from the BETAMAX era.. :)

[@powerbanger69]

I believe this might work

[@dynad00d15]

@@powerbanger69 if it works or not is not the issue here..

[@PepeGod1st]

Don't forget to overclock the drum motor for extra performance 😂

[@tarajoe07]

Any other raid is just a waste 😂

[@charlesanthony3248]

As soon as you get the drum spinning, attach a scope to the timing track and capture the wave form and timing. With that you should be able to build and debug a timing track writer.

[@UsagiElectric]

That's the plan! My friend Lloyd has a G15 as well, and has figured out which pin on the Canon connector to check, so we're all primed and ready, I just gotta get the electrons from the breaker box to the machine.

[@JD3Gamer]

Seeing that wire mess really put into perspective the complexity that is hidden by modern nanoscale computer architecture.

[@shawnaburns5158]

Lots of spaghetti for sure😅

[@SimonBauer7]

yeah it is, of course how even in ics Things are more orderly, and "cable managed" (if you can call it that)

[@agranero6]

I thought no one else would be crazy enough to calculate the density of something you can't dismantle to know its composition. This was the most incredible part of this video. Coolest thing I saw in the last 3 months.

[@FinnBojorgensen]

That drum brings back memories. In the late sixties and early seventies, I wrote a few programs on a computer that used a drum as "mass" storage and 5 KBytes of core memory. I remember that the instructions in case of loss of power were to wait for several hours before powering up so as to insure a complete cooling of the drum. The drum had different dimensions compared to the one you're working on, smaller diameter and several times longer so during the cooling it tended to warp slightly due to the heat migrating upwards. If you powered up too rapidly, there was a risk of head crash due to the warp of the drum, so you may be right about the thermal theory.

[@jussikuusela7345]

15:10 My father was a "linotypist"... he never learned the new computerized system so he had to eventually change to other tasks in the shop in the 80's. There is a whole page about the machine on Wikipedia. Awesome technology for its time, and possibly one of the first applications of binary code in the matrix sorter.

[@SeanBZA]

HP 1000 was part of an ATE system I used in the military. Computer was the most reliable part of the entire ATE, while the mercury relays it used were the source, along with connections, of most of the troubles we had with it. Yes we did have our own guru who was in charge of the ATE system, and plenty of work in removing mercury relays so that you could take it, tap it to settle the mercury drop to the correct position in the bottom of the relay, test it a few dozen times, and solder it back in to position. Self test would then run for nearly a full day, testing every single relay, and every single combination of the internals, before you moved to the self test testing all the DUT cabling as well.

[@douro20]

The 1218 on the USS Midway is still fully operational. And there's a working 1219-B at the Vintage Computer Federation in Eatontown, NJ.

[@dougshaw4287]

Thank you so much for these wonderful videos. Wish I could have been at the open house. My first real programming experience was on a G-15 in high school in 1963. Fond memories of programming in INTERCOM, assembly language and ALGO, connecting an audio amp to the track 19 (I think; might have been a shorter track) banana plugs to play music, poring over schematic blueprints with a friend trying to understand the instruction decoding, etc. I believe System Source Museum also has a DEC PDP-5, my next computer on which I built up a callous on my index finger by repeatedly swiping all the metal toggle switches to clear them while toggling in the RIM loader (to bootstrap the machine from paper tape on the ASR-33) or binary, self-assembled programs. 10 years later used the Univac 1218 (U-1500; AN/UYK-5) on board the Navy repair ship USS AJAX (AR-6). I will be looking forward to your future videos.

[@UsagiElectric]

That's awesome that you actually got to use a G15 in anger! We actually have tape back ups of Intercom and Algo, so hopefully, I'll get the opportunity to experience those first hand as well. System Source does indeed have a PDP-5, it's a really gorgeous machine with its big round CRT. That's awesome that you got to use so many of the machines on display at the museum! Thanks for checking the videos out!

[@jnelson4765]

The open house was my first trip up there, their Sun, Cray, and SGI collection alone is pretty damn impressive. Definitely an awesome crowd.

[@UsagiElectric]

Thanks for coming out to visit! It's an awesome museum for sure!

[@billklement2492]

Sorry I missed you guys! Monday is complicated. The calculator was what got Wang started. While there were a lot of Display Writers out there, Wang owned the word processing market in the same way Word Perfect owned it in the early PC days. A friend of mine specialized in transferring word processing data into different formats. They did court reporting and input into Wang systems, but could send you the data in any word processing format you asked for. He had the first Compaq 386 in the DC area. Pretty cool! Thanks for the video!

[@UsagiElectric]

Monday was just how the trip worked out this time, I think if we turn this into a yearly thing, we'll figure out a better day for people to come visit! The Wangwriter that I have is an excellent Wang Word Processor (unfortunately, I do all my typing on a modern computer, so it doesn't get used that much since it can't really do anything else). I do really like Wang's early stuff though, they were definitely swinging for the fences!

[@msylvain59]

Can't you get access to a portable X-ray fluorescence spectrometer ? It would give the answer about the alloy and maybe also some hints for the magnetic coating.

[@inothome]

That's what I was expecting him to say they used... Not the mass calculation.

[@stephensanner1315]

If you're serious about trying to recoat the crashed drum, reach out to Kodak in Rochester or Harman Technology/Ilford in the UK. Manufacturing photographic film has much the same requirements as the drum memory: an extremely even, micrometers-thick homogeneous coating with finely-dispersed solids deposited onto a curved surface. And film needs multiple layers to boot. This is squarely in their wheelhouse. Wish I could have been there for the open house! I'm really hoping that there's another one sometime. Maybe for when the G-15 is all set to return to System Source? 😉

[@macgvrs]

Got my fingers crossed for you that it powers up with no major issues. Definitely looking forward to the next video.

[@jeremiefaucher-goulet3365]

5:20 These connectors look like the ones on the AGC that @curiousmarc and his team had great difficulty to source and re-create. Nice to see this was used elsewhere, and were not just custom to the Apollo program.

[@Iceykitsune]

Apollo used a lot of off the shelf components.

[@jeremiefaucher-goulet3365]

@@IceykitsuneThat kinda is my point here. These connectors weren't very "off the shelf" seeing how difficult they were to obtain for the AGC work. Hence my surprise to see them on the Bendix. Assuming of course they are one and the same....

[@Iceykitsune]

​@@jeremiefaucher-goulet3365 They were off the shelf in the 60's, but have since been discontinued.

[@brentpolk2431]

This sort of stuff is what got me interested in computers when I was 12. I'm 48 now and because of the fascination in 1986 I still love this older stuff! We are living in an amazing age of silicon history...

[@dhpbear2]

8:51 - That WANG Calculator was a WORKING exhibit at the Museum of Science in Boston back in the late 60s. It consisted of the main unit that was behind glass and 4 of those NIXIE tube keyboard/display units attached. I *DO* remember that the keys had a very short 'travel'.

[@rlzr.]

I just can't wait for next Bendix video! Your videos are entertaining and made really well. It's a must-watch for me every Sunday :)

[@UsagiElectric]

Thank you! It's awesome to hear that you're enjoying the videos!

[@JD3Gamer]

4:46 Shout out Minnesota! Heck yeah!

[@Scott-i9v2s]

Seen any ModComps anywhere? NASA used a few of these mini-mainframes in a so-called "frozen" state, ie NO changes/updates/&c whatsoever were allowed, so that they were truly identical in every aspect. The 2 that I was sysop of in the mid-1980s still had toggle switches & the same removable disks as your Centurions have. OUR problem with them in The Netherlands was the power supplied to it. The conversion from 220V to 127V was right at the edge of its tolerance. Flexing computer-room floor panels (built on a CARPET under-flooring!) caused electrostatic sparks when one walked along the rack-mount cabinets that resulted in frequent power-downs... From ModComp's Irish technician I remember learning what "hang fire" meant, but very quickly forgot how to use those toggle switches.

[@danmenes3143]

It was great meeting you at System Source!

[@absalomdraconis]

The 400 Hz power on Navy ships is probably because the higher frequency allows smaller transformers to be used for the same power: aircraft use the same frequency for the same reason, and 400 Hz is still low enough that the advantages of 60 Hz will likely still apply (though I'm not sure about arc-snuffing in switches...).

[@trox355]

Such an excellent time. Thanks for putting this on! My office is only a half hour away and I never knew about this before your first video.

[@N8Monk]

It was definitely worth the 9 and a half hour drive to check out the museum! We had a great time!

[@tubeDude48]

It was exciting to see the Heathkit H-8 Computer and the H-9 Monitor!

[@RoundSparrow]

Great Episode. Good writing, good images of the hardware, good staging. Thank you!

[@UsagiElectric]

Thank you so much! I wasn't sure how the editing would turn out this time, but I'm glad to hear it came out well!

[@ianneill9188]

Wow, just fantastic! Loved the mini tour around the museum, and the dive into some of those super machines. Thank you.

[@UsagiElectric]

Thank you so much for checking the video out!

[@danmenes3143]

Those heads are HUGE! I'm officially back in the "wrap the bad drum in audio tape" camp. Wrap the tape in a helix, so each track effectively has a diagonal splice. I think you can get it flat enough. Maybe shellac for a cement--thin, and if things go bad it can be removed with alcohol.

[@exidy-yt]

i've never hated living in Vancouver B.C. (west coast of Canada) as much as i did hearing about this open house at System Source knowing there wasn't a snowball's chance in hell of attending. :( Still super glad it turned out so well, and may the day come when I can afford to travel wherever I want when I want!

[@barryhills6744]

As a ex-Bendix owner I watch the G15 revival with enormous anticipation. I have a handful of new old stock parts if you are in need. For example, I just stumbled upon unused stock of the T1425 light sensor for optical tape reader if you need or want.

[@TheHylianBatman]

I'm glad that the open house was a fun success! Also glad that we now know more about the Bendix!

[@WolfmanDude]

Interesting, the drum looks like it has been coated and them ground to be flat. That would make your job to recoat the drum way easier. You just need to find the correct "magnetic paint", coat the drum in excess. Then any machine shop with a precision grinder can make it flat and round. They do this all the time for bearing pressfits!

[@chrisjpf33]

It was great seeing you in person again. It was absolutely worth the trip! Thanks for all you do!!! Can't wait for the next video.

[@UsagiElectric]

Looking forward to digging into that HP 120B!

[@RobAbshear]

I was an engineer on a Honeywell DPS6 in the US Navy. It was a huge system. The shipboard versions were in these big, black, ruggedized racks. On shore-based installations they were in normal cabinets. We had card-punch/readers, 10 inch mag tape drives of various types. High-speed printers. Chain-train printers. There is very little information on the Internet about these systems. This system was used primarily for payroll and accounting on the ships I was on. The OS was GCOS Mod 400. I still remember the front panel boot sequence stop/clear/load/ready/execute. lol. Those were the days. Serial terminals running all over the ship.

[@ipavemyownroad]

I saw that you went to System Source and changed my whole summer trip up the East Coast to Quebec to give me time to see it. Thanks so much for telling us about it!

[@ristopoho824]

I have been binge rewatching tech videos and it bothered me that there was a channel i don't remember that had videos about, well. Well it's tech time traveler. Thank you very very much for mentioning him. Will continue the binge there after this video. Such amazing channel, and underappreciated too, not popping up in youtube frontpage unless you know what to look for.

[@afreezaphorogiancossack2194]

I was aware that Bendix was involved in early computers but of course I mostly know them from bicycles LOL. This is my first time seeing any of their computer hardware. Awesome!

[@davethetaswegian]

Interesting to see the Wang 360. As it happens I have a complete Wang 362E system that I have been trying to figure out what to do with. And by complete I mean everything, The 362E, 370 programming keyboard, 372 Storage unit (16 extra magnetic core registers), 3 X 371 Card readers, plus programs on card, blank cards, and a full set of manuals and documentation. While it is in fairly good physical condition it would need a full restoration which is beyond my abilities.

[@seanmarsella3071]

I found your channel by accident. Thoroughly enjoying watching you try to get all this vintage tech up & running again.

[@clyde3013]

Ive been waiting for this vid! Had a great time at the museum.

[@nasabear]

It was great meeting you and all the others at the open house.

[@ernstoud]

04:19 … the Univac 1218 had an MTBF of 2100 hrs. Geez… every 3 months a breakdown…

[@highpath4776]

presumably the mechanical and power feed lines followed by odd resitors and transistors.

[@danielkawano206]

Hi David, I have been following your channel for a while and I can assure that you are (and probably Adrian Black too) one of the few mainstream KZbinrs in the retro community that still preserves the same brigth in your eyes since the beginning of the channel. I posetivelly appreciate your contents but what I most admire is your enpathy and you excitement about your projects. So Bro, I am sure anything you upload in your channel is going to be Epic! A warm regards from you followers from Brazil.

[@ahbushnell1]

If you are using a 50 amp breaker the continuous load should be 40 amps or less. So 38 sounds good.

[@edgeeffect]

Yeah... I'm not sure how I'd feel about working on priceless vintage computers in front of an audience... however polite. But it looks like you got the drum swapped without freaking out... so go you! ;)

[@fredblonder7850]

Just to be pedantic, I shot my video with an Olympus OM-D, not my phone. ;-) Also, regarding the Wang 360 Calculator, I used one of these in 1970 in a class given by the Maryland Academy of Science, back when it was a single rowhouse on Mulberry Street in Baltimore. This video did not show the bizarre manual punch-card programming system it used.

[@velho6298]

Can't wait for the timing issues in the next episode!

[@bcostin]

I really wanted to see you guys at SystemSource but was out of town that week - hopefully next time! My grandmother used IBM DisplayWriters back in the 1980s while working for a government agency. When she retired, she wanted something familiar for her own personal use. As I recall, my father and I set her up with an IBM PC-AT running WordPerfect using a WheelWriter for output.

[@wdolgae]

Need to take the drum to a PCB manufacturer and see if they can run it thru the oxide line. That would put a new layer of magnetic material on it!

[@muchosa1]

You need a shop close to System Source to restore some of the equipment.

[@computerdude8726]

man, that drive is massive.

[@landspide]

Visited in October, amazing experience.

[@SO_DIGITAL]

OOh, I'm tingling with excitement to see this puppy running.

[@jms019]

What a great place I must visit.

[@beefchicken]

Woohoo thank you for showing the Linotype! That’s a Model 31 with a Hydraquadder, I have the same model made 1224 units after theirs in my garage!

[@RetroJack]

Having watched your journey with the Centurion, this is equally as interesting and I can't wait to see where it goes!

[@uki352]

Is there a way to machine the scratched drum and re-coat it? Wouldn't that be a really interesting project? On the other hand, someone could hide some FPGA down deep inside that emulates the drum memory, so all known machines could run again. And you can pull the heads back to a safe position on all the working drums to preserve them for an even longer time. Even an STM32 would be fast enough to do that and enables some serial / USB debugging. Having a safe option to run the unit any time but preserving the original state by pulling a plug ad inserting it in another socket seems fine to me. A little like changing the cap at the APPLE I but keeping the original one aside with it.

[@WelcomeToMarkintosh]

Wow-I've been waiting for this episode! I'm so sorry I missed it-I really wanted to meet you, David. Bob told my buddy & me about you last time we were there & that's how I got hooked on your channel! Looks like you and the entire gang had a blast-I hope you do it annually, I'll definitely be there next time. Isn't that place great? I live about 45 minutes away and have also shot some great B-roll & interviews with Bob for my new Mac based channel. Can't wait to see more on this BEAST! Thank you, David-YOU are EPIC!

[@dadawoodslife]

First computer i ever used was a Data General Nova at Nottingham University, Physics Dept, UK in 1977. Core memory and boot strapped with a switch panel on the front I think it had 4 teletype terminals, each allocated 4K of memory if i remember correctly.

[@CATech1138]

i would think one of the non magnetic stainless steels.....that drum is a flywheel, weight is a benefit towards reducing change in velocity---this is extremely important in maintaining timing within the very small tolerences available at computer cycle speeds.....heavy and non magnetic as well as cost effective Titanium was prohibitively expensive due to it's requirement in aerospace in that era.... Ben Rich's writing about getting Ti for the SR-71 in his book The Skunkworks is i believe the easiest reference to find on the topic.... Ti is the literally basis of the concept of Unobtanium....it is also very light for it's strength and so wouldn't be a good choice for a flywheel in a ground based device.... of course i would very interested in what design criteria would be met by Ti should i be wrong, any drum memory engineers out there?

[@kpnconsulting8739]

Yeah, I thought of stainless as well when I looked at it. Nonmagnetic and dimensionally stable. I think the gouge happened because some tech dropped a tool when servicing the beast.

[@OscarSommerbo]

@@kpnconsulting8739 I tried to get my brain to remember thermal expansion, and to close a 0.0254mm gap would require more than a 1000C. So a dropped tool seems much more likely. Invar (another aerospace metal) has a thermal expansion coefficient 2.5 higher than aluminum, which makes the thermal theory more plausible but still improbable.

[@idio-syncrasy]

I agree. Doesn't seem likely it was Ti. The question would be why use such an expensive material that was nearly impossible to machine and.balance.

[@robot797]

yay more tube stuff not the tube stuff I wanted but any tube stuff is good enough

[@SOMERANDOMDUDESomething]

The 6360 floppy drive looks like a toaster

[@maskddingo1779]

OMG! I see an Ithaca Intersystems DPS-1 there! I have one that also includes the original dual external floppy drives that I restored a couple years ago. I also managed to find an unbuilt ithaca intersystems 256k ram board (and built it). Everything works! Since then I have been collecting Ithaca stuff. I need to go to this museum. I wanted to come (i live in pa) but i messed my car up the day before.

[@dhpbear2]

8:25 - It must be similar to the keyboard shipped with the original IBM-PC in 1981. I recall a 'ding' sound and feel. UPDATE: Aha! Thank you! (10:30)

[@KenjiUmino]

similar, but different - the IBM model F has a different 'ding' sound - I bet there are some ASMR keyboard typing videos on youtube for comparison

[@retroatx]

I loved the SOL20. I seem to recall they had an S100 buss connector

[@dhpbear2]

4:35 - A 'militarized' tape system? The mind reels :)

[@WagonLoads]

If you ever run across a S-100 bus computer called Xitan made by Technical Design Labs, I hope you will make a full video on how to make it run...

[@btraker]

Wish I could have joined you at System Source, I work a half mile from there! Didn't realize it was an RSVP event until the event had no more space left.

[@twol78s90]

Hello, David. It is absolutely awesome that you now have a good (at least so far as is known) drum for the G-15. I just hope all of the heads are good, especially those on the timing tracks. It will be so wonderful to see the G-15 back to its operating glory! I know you can do it! Speaking of timing tracks, there was an electronic calculator made back in the 1960's called the Wyle Laboratories WS-01 that used a strange type of magnetic drum (kind of an inside-out one) that had a timing track for the timebase for the calculator. It was an all-transistor calculator, with a glorious CRT display that used gated combinations of sine and cosine waves to generate the digits. They almost look handwritten on the face of the CRT. Anyway, very few, if any of those machine survived (the original prototype breadboarded machine is known to exist, but it is very, very unlikely it will ever run). The machines developed problems in the field from bumps and movement that would crash the drum, rendering the machine useless. The inside-out drum-based machines were replaced with model WS-02 that used a magnetostrictive delay line instead, solving the problem. That said, I noted in this video that you were fascinated with the Wang 360 calculator they have at System Source Museum. If you are ever in the Portland, Oregon area, please consider yourself invited to come see the Old Calculator Museum outside of Portland, OR. I know its a big jaunt from Texas, but you go to System Source in California, so maybe it's not too far out of the way. I examples of the Wyle Labs calculators, which are really amazing. I also have an operating example of every model of Wang electronic calculator made /except/ for the Wang 500 (which I'm in a long-term project to restore), including the Wang 370 and 380 Programmers for the Wang 300 calculators, as well as the amazing Wang 700 and 600 machines, and beginning of Wang's first programmable calculators, the Wang LOCI-2. That doesn't mention a few hundred other old (pre '73) vintage electronic calculators, all out on display to be used by visitors, including both HP 9100A/B and the 9810/20/30 machines, an HP-01 calculator watch(simply amazing), many Sharp and Casio calculators including some of the earliest machines from Japan, and lots of documentation and ephemera from the heyday of electronic calculators. If you wish to come visit some time, just go to the Old Calculator Museum website (oldcalculatormuseum.com) and send me a message from there.

[@markryan2475]

Fantastic video - really liked the Univacs

[@datasilouk1995]

UCSD P-system. Oh, wonderful. Takes me back to my days of Sage IV , Pinnacle, Apricot, ACT Sirius etc.

[@aserta]

3:11 crazy to think that that machine is closer to real bugs inside the system than it is to today. :))

[@garyarnold8288]

We had the 1218 and three 642 B NTDS computers on the USS South Carolina. It was commissioned in 1974.

[@chibichabot9293]

That's a glorious sounding keyboard on that display writer

[@thomasguilder9288]

Wow many years ago my dad brought three DisplayWriters and the big printer home when they got replaced by ibm pc‘s in the company. I think I was about 9 to 10 years old and started learning english words using the displaywriter gui and looking through the service data books :) The set included a service 8 inch disk which could run several system tests and make memory dumps, accidently I destroyed it by pushing the little pushbutton on the back of the unit which dumps the ram content on the floppy… great days… later I had a 386sx and started tearing down the displaywriters, if I just kept one! Especially seeing how much they ask for the keyboard 😅 still have some of the special hybrid packaged chips in aluminum cans in my drawer salvaged from these units and the typewheel punch electromagnet !

[@vinatron8075]

Interesting did you know that there was something called DisplayWrite/370. It was designed to be the same interface as the display writer but on a mainframe 3270 session pretty neat.

[@vinatron8075]

Posted a photo on discord in case someone wanted to see the 370 version.

[@NoNameForNone]

The dark grey color sure looks like titanium, though other metals are that color but not the weight. If you get your hands on a really good (and I mean superb) ohm meter, titanium has about double the resistance of alluminium. Do pinch though the oxide layers thoug while measuring.

[@williamsquires3070]

I wonder if the 6502 on that Apple I was one of the original “buggy” ones that lacked the LSR instruction? My guess would be, yes.

[@dhpbear2]

5:58 - That floppy subsystem looks like a TOASTER!

[@oliverer3]

Now I want to design a beam spring keyboard... I swear for every one of your videos I watch I end up with a new project idea.

[@saintpaulsnail]

In the late 70s I worked for Honeywell, with the H316 as my usual target. I heard that H316's were used as multiuser systems. Early FORTH environments could support multiple users with everyone getting their own terminal buffer and dictionary.

[@esra_erimez]

Hello wonderful person watching this wonderful video

[@dhpbear2]

3:43 - These panels look oddly Art Deco!

[@larryk731]

The wang calculator family uses RPN - it's not as complicated but it is very different

[@ToTheGAMES]

Love the story!

[@miketriesmotorsports6080]

Man, I am sooo dumb. You were at System Source on a Monday, and I was looking forward to coming out for the open house for WEEKS! But, for some reason, I kept putting it on my various calendars as a Tuesday! So, when Tuesday came around, and I went to verify... 😞

[@kanalnamn]

Considering how difficult titanium were/are to get your hands on in quantity and the high price... I can't really see why they would use that for the drum. I can't think of any immediate advantage..? (Edit: high density and non-magnetic?)

[@highpath4776]

Being Bendix, and the computer surely could not have sold in major numbers , the availiblity of any metals would have been possible. I think I am tending to stainless steel - what are its thermal characteristics. ( and if it "shrinks" in the cold wont the magnetic layer fall off/become loose ? )

[@axelBr1]

Additionally, I believe that titanium is very difficult to work. Also, although denser than aluminium titanium is stronger, and is used in the aircraft industry because a titanium part will be lighter than the equivalent aluminium part, so the drive should have been lighter than expected.

[@gregcarter6406]

Puff the Magic Dragon Smoke Time? But, your comment about the metal type of the drum is valid. It is one of the reasons why Titanium is used in aerospace applications for just that reason.

[@terrypokorny3858]

I am looking for tge next video on the g15 when you can get it all spined up

[@dannydoolhoff7657]

If I had known the Display Writer was so versatile, I would have kept the 2 I acquired in a bulk pallet purchase... Long gone now.

[@Professorke]

Why do the sweetest, most sympathetic and intelligent people always live on the other side of the globe? You are someone everyone wants to be friends with. Glad I can follow you on KZbin, it brings some joy to my heart after all.

[@Renville80]

The 6502 in that Apple 1... it looks to be early enough (51st week of '75) it is likely the original version with the ROR bug. Adrian wound up with a similarly old 6502 and his was confirmed to have the original buggy silicon (think he showed documentation stating the ROR instruction was not usable on 6502s made before mid '76).

[@adamchurvis1]

9:45 Bought my TI-2500 (2510?) -- my very first calculator -- for $75 back around 1972 - 73 when I was about 11 years old, a little over 50 years ago. Got frustrated with not being able to structure a math problem correctly and punched the calculator once. That's all it took to destroy it.

[@Ragnar8504]

400 Hz AC is popular in airplanes because the amount of iron required for a given power rating in a motor or generator (and transformer) greatly depends on the frequency. The lower the frequency the bulkier everything gets. I guess it made sense for the military to use the same systems on boats too.

[@SimonBauer7]

this is also why modern psus are switch mode, so chop up the ac to a higher frequency, simply because its more efficient.

[@JCWren]

You need a Niton XL5 Plus Handheld XRF Analyzer for determining what the drum is made of. It's one of the less expensive models at only $12,848.50.

[@lokelaufeyson9931]

old computers is impressive, modern computers is "nah, they go a bit faster than the previous model".. The work alone to build the old coputers is a day and night situation. Love the modular calculator :) Bigger is better

[@ristopoho824]

I WANT to visit that place. I really want to. A long way from here, and i'm not usually willing to travel a lot. None of my friends would be willing to travel for a museum, those that were at the Chania trip with me went shopping while i crawled the museums. Could go there myself, but going to a foreign place alone would be terrifying. Also worth it. For the experience of going somewhere alone. And the System Source. Oh yes please i want to go. I will. Not yet but someday.

[@ristopoho824]

I might have commented that before, but yea. My goal in life is to study enough that i get to work on amazing things like these. I'm jealous of you, well not jealous, more like inspired. Someday i will get called to a museum to get some obscure piece working. Talked with my dad yesterday about what he used to do. Pretty much exactly that. So unknowingly i have been following in his footsteps. He's not on your level, not many are. I'm somewhat your age, and still not there on my journey. But getting closer by the day.

[@SimonBauer7]

reading the title i imagined you just secretly swapping the hard drives and then running away with the working one 😂.

[@Plarndude]

I'm used to a pretty cold computer room. Purposely keeping a room at about 80 is nuts!

[@jwhite5008]

Not with a hundred of filaments around, literally designed to heat the tubes to a specific temperature range...