Relay Computer

Relay Computer - Memory

Рет қаралды 3,455

Күн бұрын

I'm exploring different memory options for the relay computer, from old-school capacitor-based to a more modern Static RAM that has way more memory than we'll ever need.
Chapters:
0:00 Intro
0:47 Exploring "old-school" memory options
2:14 Capacitor-Diode Memory - Prototype demonstration
4:29 Modern RAM - Deep-dive into the 62256N
5:37 Modern RAM - Prototype demonstration
9:05 Isolation - A good thing for RAM and Relays
10:18 Design & Build Time!
12:06 Testing the new RAM-based board
13:59 Outro
Music:
It was a Fine Day - South London HIFI
Long Road - Futuremono
Sun Awakening - Futurmono
Thank you for watching, and as always I welcome any feedback or ideas for future projects!

Пікірлер: 51

@DanafoxyVixen 2 ай бұрын

I had never heard of Capacitor memory being used for relay computers before, thats so cool

@carstenfrandsen 2 ай бұрын

The clickety-clackety sounds from the relay - well I think it is so soothing - and probably not for hours and hours. Great video.

@dipdoting 2 ай бұрын

Thank you! I can't imagine what it would've been like working on a large-scale relay computer like the FACOM...would be cool to watch but I'd need to write the code in another room!

@Ernzt8 2 ай бұрын

I never get tired of clicking relays

@txd 2 ай бұрын

This is the best thing that's happening on youtube right now :D

@dipdoting 2 ай бұрын

Wow that's a huge compliment! Thank you!

@txd 2 ай бұрын

@@dipdoting You are welcome. Looking forward to the upcoming videos.

@AnnaVannieuwenhuyse 2 ай бұрын

And he's back! Uh-oh, it looks like you may have forgotten to clean the lens on your camera for the intro b-roll. The bloom and lack of contrast is usually a sign of that.

@dipdoting 2 ай бұрын

Good catch - yeah that b-roll is like a Xerox of Xerox...I didn't have the original footage and needed to grab it from my previous 720p KZfaq video. Lesson learned --- keep backups of all my hires b-roll 😉

@adamclark1928 2 ай бұрын

Congrats on the 1k milestone!!

@cweletronica5628 2 ай бұрын

Amazing job! Keep going!

@faneuil1 2 ай бұрын

Been waiting for the next installment!! Love this

@dipdoting 2 ай бұрын

More to come!

@colonelbarker 2 ай бұрын

Great work! Really interested to see how the capacitor diode memory goes

@dipdoting 2 ай бұрын

Thank you!

@smichels5117 2 ай бұрын

Fantastic project and video! The sound reminded me of the old cross point switches used in telecom even up into this century (although, much less than in the early to mid last century.) keep up the good work!! I’ll be watching, of a certainty.

@dipdoting 2 ай бұрын

Thank you!

@SamuelFlint 17 күн бұрын

If you used two relays per bit, you could have the capacitor memory without the separate clear line. The first relay would select between ground and vcc, the second relay would take your write signal, connecting the first to the capacitor. So, write + zero data = ground capacitor, write + one data = charge capacitor. You would power write on read as well, for your 'refresh'.

@smudgerdave1141 2 ай бұрын

Can't wait to see you run a program to blink an LED 😊

@dipdoting 2 ай бұрын

Just for fun I'll have that as a front control panel option --- one blinking light! 😂

@awesomecronk7183 2 ай бұрын

Sweet 😎

@damianbutterworth2434 2 ай бұрын

I used a few relays to make a keyless ignition on my motorbike in the 1980`s. No one could work out how to start it. Even got stolen twice and they never got it running.

@NielsNL68 2 ай бұрын

super, I like the idea of the capacity storage. That said i'm wondering what the benefits are between the registry busses you made and the use of the capacity storage. Those let bars you used in the demo looks much cleaner then the separate led's on you boards.

@dipdoting 2 ай бұрын

Technically you could use capacitors for registers as well. One thing with capacitor memory is that it needs to be refreshed from time to time, easier to do with all of that in one place.

@RetroRogersLab 2 ай бұрын

The first PCB I ever sent out for production was the A/D Register board for this relay computer. It had a few mistakes but I was pretty jazzed with how well it came out. I designed a daughter board the uses simple pin headers and a socket to plug into the main board at a right angle. This makes the LEDs much more visible. I also went with surface mount LEDs and resistors to make the board smaller. I'm intrigued by the capacitor memory idea but isn't it still one relay per bit? I'd imagine you'd be limited to 64 bits per board at that rate.

@dipdoting 2 ай бұрын

That's great! I thought about using right-angle for LEDs but my intention is to have everything in a case and have a front panel so they are for "debugging" purposes - at least in my mind. For Capacitor memory we'd need one relay for every 8-bits (capacitors) to enable a byte for read/write. I'm playing around with PCB designs, and I think I'm going to need a bigger boat...er...board for capacitor memory.

@RelayComputer 2 ай бұрын

Excellent video and explanation as always!. But I am confused as whether the capacitor memory still needs one relay per bit, or the same relays will be shared for a bank of memory cells after memory/bit address decoding. I understand it's the latter. The Mercia relay computer site seems to omit the need to recharge the capacitor while reading memory, unless I missed something. I'm sure you will cover this in more detail in a future video. Determining the right balance for capacitor size should also be interesting. I think the larger it is the better as this should provide more idle storage time, but maybe writes and reads become somewhat slower if the capacitor is too big (?)

@dipdoting 2 ай бұрын

Thank you! I saw your other comment below but yes a relay can be shared for a bank of relays - but there'll need to be some supporting relays for clearing, write/read flow control etc. It'll be a fun adventure to figure this one out!

@maxmn5821 11 күн бұрын

What do you think about using latching (bistable) relays for memory?

@linksgard2 2 ай бұрын

do you have plans to release the circut designs or sell pcb's? id love to assemble one of these as well.

@dipdoting 2 ай бұрын

For sure - Once the build is "done" (meaning it's stable and running some code) I'm going to do a REV2 to fix-up any obvious issues...then I'll post the designs and pcbs for anyone to try out!

@VladoT Ай бұрын

Sony ZV series cameras have a very good quality for their price, try that.

@dipdoting Ай бұрын

Thanks - I ended-up with a Canon Mirrorless - hopefully you'll see some improvement to resolution in the videos.

@timseguine2 2 ай бұрын

Didn't the electromechanical circuits in for example (pre solid state logic) pinball machines and jukeboxes mostly use latching based memory? Is that strategy not really usable in a general purpose computer?

@dipdoting 2 ай бұрын

Yes, they did, and this relay computer uses latching relays for the registers to store values. Great video by Technology Connections about pinball and relays here: kzfaq.info/get/bejne/q8tdZK2gr7fFdZs.htmlsi=L7mgr5G5tZpTFN9Z

@mattbettcher 2 ай бұрын

Will you need a relay per bit with the capacitor memory? How many bits of memory are you planning on designing for the capacitor memory?

@RelayComputer 2 ай бұрын

I asked that same question. I think he just demoed the concept in this video, but in practice he will share the same relays for a bank of memory cells. So only the capacitor and the two diodes really count per memory cell element. This should be possible because memory cell addresses must be decoded anyway, so only a few cells are accessed at once while the others remain idle.

@dipdoting 2 ай бұрын

It will need one controller relay for each row of 8 capacitors representing 8 bits, and then 2 diodes for each of those.

@peterpan408 2 ай бұрын

Capacitor memory? You mean SDRAM.. It must be refreshed by the memory controller fairly frequently.

@dipdoting 2 ай бұрын

The goal is to refresh at each read cycle. For longer runs I'll need a ROM routine or something that refreshes at regular intervals. Trying to experiment with different sized capacitors to find a good balance between size and time needed between charges.

@bascomnextion5639 2 ай бұрын

Have you considered bistable relays

@dipdoting 2 ай бұрын

I haven't considered them yet - looks interesting - would add some complexity in terms of needing to reverse polarity to reset but doable. Of course, cost is also a factor for me 😁

@bascomnextion5639 2 ай бұрын

@@dipdoting In quantity they would be not much more than capacitors and they are non volatile once operated require no power , maybe not for a large amount of memory note they also come in dual coil types one coil sets the other resets so its a flip flop!

@GianmarioScotti 2 ай бұрын

Charging those capacitors through a relay is going to kill that relay in no time.

@dipdoting 2 ай бұрын

Interested in hearing more on this - the Comm to NO/NC are rated for 2A @ 30VDC for 100,000 operations. Does charging capacitors cause further stress on contacts as opposed to energizing another relay? If so, I could socket those relays to make it easier to change them out I suppose.

@GianmarioScotti 2 ай бұрын

@@dipdoting An electrolytic capacitor typically has ESR (equivalent series resistance) values of few milliohms, and in case of very old electrolytics up to an ohm. Divide the voltage you apply to a capacitor to charge it to obtain the peak current. Same applies to discharging the capacitors. Sorry for being the bearer of bad news.

@cesibley 2 ай бұрын

I was happy to hear you are still pursuing capacitor diode memory. Using a model RAM chip just seems like cheating. Disappointment!

@dipdoting 2 ай бұрын

Totally agree - Whenever I see chips on relay computers it takes away from the concept - this RAM will help me work the bugs out but fully intent to have a working capacitor memory in the future!

@beanMosheen 2 ай бұрын

It's not really cheating to me if you need the memory depth. Repeating hundreds, or even thousands of a circuit doesn't seem more "pure" to me from a practicality standpoint. Maybe have some registers as cap memory, and bulk memory as dips if you want to flavor it a bit.

@mutzbunny Ай бұрын

I dont really like the idea of the CMOS ram chip. its so out of place. could we come up with something kinda period correct? idk, i dont think im smart enough to think about something better tbh...

@dipdoting Ай бұрын

I hear ya, it feels like cheating to use a RAM chip --- In behind the scenes I'm working on capacitor memory so that should be interesting. I'll probably need a whole additional enclosure just for the memory!