I'm in awe of your electronics skills - I wish i had them!

Fascinating video. Also, just curious what app you’re using on the phone there for the audio pickup. Ta

That was fun (at least to watch ;), thanks for sharing it.

Why? !

I miss Radio Shack. The last thing I bough from them was a cordless home phone for my ex's grandfather in Fort Myers Florida. That was probably 2011. I went to the back of the store where all the components used to be in the big long gray drawers and it was all cleaned out, no real parts to speak of. A few bags of resistors hanging on a card, but man.. when I was a kid in the 80s Radio Shack was 15 minutes from my house growing up and I spent a LOT of time there!!

could you build a buffer box that could receive one buad on one side and send at a different buad on the other side?

Wow! Very interesting!

Working on anything with a device called a ‘velocity transducer’ is maddd nerd currency bro. Hat’s off. Jealous.

Nicely done. Sometimes old computer repair just goes like that. Have fun at VCFSW!

Great video and a cool hack

Quick tip with the desoldering iron is that you can suck the solder out and break the pin free at the same time. I have that same RadioShack desoldering iron and as the solder melts I apply gentle pressure to the pin to center it before I release the bulb. This gives enough room to break the meniscus once the solder is gone, and the IC usually lifts right out by hand.

I LOVE those RadioShack solder suckers! Have two of them and they are absolute wonders for desoldering pretty much anything.

Love your videos, but the 14+khz sound of the monitors give me headaches

I know absolutely next to nothing about early computers and finding your channel randomly recommended to me has made my month! Keep working on these! It's very interesting to see as a mere 26 year old.

Are both terminals running the same CPU clock speed and processor versions? It appears there were three versions in 3, 5 and 6 MHz.

*_HEADS_* : loaded *_MY HEAD_* : unloaded

so it's not y2k compatible?????

9:11 That plate is why you have those giant fans you mentioned in the last video. While they don't get super hot when being cooled, they generate a lot of BTUs. While a DECVAX is not the same, it required a lot of cooling and its own power conditioner (which also needed cooling). The server room we had ours in back in the 90s had a raised floor for all the cables, a giant power conditioner and it's own several ton AC. There were other things in the room, mostly just X86 boxes running Netware (they were running a special NLM and there was like 12 of them configured as computation servers). But they didn't need it, the DECVAX did (I'm calling it that to avoid autodelete from the last 3 letters). One day the AC crashed. That room, normally like 55 degrees was 90 plus degrees in a couple of hours even with all the PC servers down. The room was at least 12x12x8, probably much larger.

I am by no means an expert on old computers. That being said, I turn wrenches every day. That air filter media looks a LOT like what newer Ford Super Duty pickups, and a lot of OE Donaldson air filter assemblies. Maybe, just maybe, you could 3D print a housing that can have the filter media replaced? Then, you can source generic air filter media and have a brand new air filter that is completely serviceable.

not the first hard drive 1956 - IBM 350A, shipment of prototype disk drive to Zellerbach, SF CA, USA?

These relays are so like, soft sounding. They aren't as aggressive as others lol

Stupid story about the PCB boards for the ADDS Regent series. All board chips had a name legend identifying the chip used. The son-alert which sounded local bell (aka teletype like) had an ID legend it said "Beep Beep" but it could not be read because the sounder cover obscured it. Someone in sales got peeved when a customer inquired about it. Engineering services got a little reaming out for it. Sales people are just too stiff, loosen up dude and dudets.

Question at this point: If you use 9600 baud but write a program that throttles the output to 300 chars per second, does it still flicker?

When I heard the pc first boot up, the beep, and the floppy drive seeking it literally brought me to tears. I was a SYSOP of The Lair BBS in 1988 and it has been forever since I had last heard the bootup noises. Thank You.

My father used some hard drive platters like these as aerial analog tv antennas at the time...

Hi David, I watch all your videos avidly, and in spite of the fact that I am an electronic product design engineer with over 40 years experience, I am in awe of what you accomplish. I particularly like this hardware fix you devised to alter the baud rate from 9600 to 4800, however you went about this in a very roundabout way, given you did not want to alter the mux board you could have accomplished this with one wire link and lifting a pin on the U_K1. Since I can't see the whole schematic I have to make an assumption as to which pin has the 9600 baud signal, all you really had to do is remove the 9600 baud from U_K1 and substitute the 4800 baud signal. If the 9600 baud signal is on pin 12 of U_K1 all that you needed to do was cut pin 12 near the PCB, bend the IC leg up so it is free of the board and link from pin 13 to pin 12, this means when the selector U_1K is in the 9600 baud position the signal is actually 4800 baud, to reverse the mod, remove the link between the U_K1 pins and link from the lifted pin back to the PCB pad that it was originally connected. No risky de-soldering and only only a pin lift. Keep the videos going, I enjoy them so much.

Loved that you used a vintage Casio Mini 8 to calculate the baud rate! To be consistent, I am sure you will use a slider rule to make any calculations for the Bendix machine 😂

Awesome solution! Shocked by format command😱

2:20: Buttler Tech's "hands-on" program seems pretty plugged-in, I see.

Well you managed to find someone who could program the Centurion without the full instruction set... There must be someone on your Discord who's just saying "Dissemble an Adds Regent 200's firmware... easy as pie!".... Well, y'know, fingers crossed an' all. Oooh... having just read your pinned comment... yeah, if it's 8085 code, I'm almost tempted to give it a try. ;)

The ROMs are a bit different... The 8516 / 9316E are 2716 pinouts and the older ones are more like a 9316A/B where the polarity of the chip selects/enables may be programmed differently at the factory. Are those jumper points 8-16 next to the keyboard cable set the same?

Brilliant! 🐰

I've been self employed in embedded HW/SW design for 40 years and we think so alike, I know what you're going to do next before you do it 🙂 I don't know if you or anyone remembers PMMI S-100 modems in the Altair age, well I was a big part of that company (understatement). If you ever get in the Dulles Airport area, we should meet, I have a feeling it would be fun and you would enjoy seeing my setup here. Love the animals, sorry you had to go through that tough time with them!

Time to disassemble!

What man in what iron suit?

"HELLORLD" never gets old 😂

Drive format - I might have missed something, but can't you connect a long cable from the big centurion to the duff hawk drive and use that to do the format? I known you have a different os on both machines, but sure the format process would be the same for the drive.

who else can say stuff like "I have a bad coil in my head" without beeing driven somewhere 😂

Trying to stab that BIG plug into that regular outlet. 😆

17:53 hmm. The unpopulated socket has an Intel 8251A UART on the other board. Maybe that IS part of the problem? Having a proper USRT would probably help in the communication...

Why has you divided by 16, aren't there more bits involved, like stop/parity? Thanks

The format program may have been removed as a security measure, to prevent curious or inept users from destroying the system. In the IBM mainframe world, it is important to keep certain utility programs away from general users and programmers. Only system programmers and operations should have access to them. In this case, I wonder if the program might have been renamed and still be present, just hidden under a different name.

i like this channel

6 months ago, I threw away old software that would run on that thing. I didn't know that many people like the old stuff. It's how I got started. I read that HDD model and knew what it was right away. What a walk down memory lane. I hope he has some single-sided floppy disks because those might only be for 180k 5.25-inch floppies. But since they are half-height, they probably will take 360k floppies.

:::::)

If you can't fix those heads, it might be worth unwinding them to see how many windings there are, maybe it could be fabricated again.

I don't know how you manage to work on this stuff without having a panic attack. 😰

I always find hand designed PCB's to be just interesting. No machine routed that, human beings had to sit down and design how those signals propagated around the PCB. That, and most of those old boards were double sided, at best. No multiple layer PCB's back then! Well, there might have been, i don't really know, my personal experience is double sided was as complex as they got.

Very curious as to why you wanted the OS on the removable platter instead of the fixed platter. To me, it would make more sense to have the OS on the fixed platter, so it's always there and available, and used the removable platter as a data drive. Would love to know the reasoning behind that decision.

Oh does that bring back memories. PCs entered my workplace around 1982 and it wasn't long before they were loaded with terminal emulator cards to replace 3278 dumb terminals on our IBM 370/145. Good times.