Craziest 'working' Breadboard - Page 1
Forum section: electronics / general

author: Moshly
author_rank: Regular Contributor
timestamp: November 09, 2015, 07:42:20 am
content: I have been following a post over at 6502.org about a guy that is building a video subsystem from only 74 logic.He is building it all on one massive breadboard, he claims he has it clocking above 20Mhz for some sections.Starts here ->http://forum.6502.org/viewtopic.php?f=4&t=3329BTW: he is making another breadboard for the soundIs this the largest breadboard prototype anyone has ever seen ? I think its

author: Xenon Photon
author_rank: Unknown
timestamp: November 09, 2015, 07:51:03 am
content: OMG! This is crazy?!But the craziest part about it is that its working!!!!

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 09, 2015, 07:55:54 am
content: whatcorrect me if am wrong but there is certainly a uC in there , the blue thing is a atmel programmer i think , and if you have a uC you don't need all that stuff cause a VGA could work with some resistors, there is a lot of project with VGA done with few component around uC.

author: pickle9000
author_rank: Super Contributor
timestamp: November 09, 2015, 07:58:24 am
content: Awesome!And he should be committed.

author: Unknown
author_rank: Unknown
timestamp: November 09, 2015, 07:59:54 am
content: Quote from: hamdi.tn on November 09, 2015, 07:55:54 amI don't think there's any way an AVR would manage this... from what I can understand of the project, it ought to be able to run rings around an Amiga in terms of graphics capabilities. In fact, it reminds me a lot of some pictures I once saw of the wire wrap prototypes of Commodore's custom chipsI'm eagerly awaiting the release of all the schematics and build logs. Given I can't even properly figure out how to make a 40*25 character display out of discrete logic at the moment, it's sure to be a great learning experience.

author: amyk
author_rank: Super Contributor
timestamp: November 09, 2015, 08:03:31 am
content: I like the neat wiring looms. Because of them, I have a feeling that this design would take even more space if laid out on 2-layer PCB.

author: pickle9000
author_rank: Super Contributor
timestamp: November 09, 2015, 08:05:31 am
content: Dave should do a blab on this.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 09, 2015, 08:09:24 am
content: Quote from: BulletMagnet83 on November 09, 2015, 07:59:54 ami opened the link and reading a bit more about the project, i assumed it's just this one pic that a board is capable of, but obviously it capable of doing much more.4 or 5 years ago i did a project with VGA, as i remember it wasn't that hard to drive the screen , of curse now if it's doing more than drawing one pic the uC will never be enough both for RAM and frequency , am not sure if he can manage to get 60Hz rate with a 20MHz that seem too low.

author: Moshly
author_rank: Regular Contributor
timestamp: November 09, 2015, 08:13:30 am
content: He is using an Atmel ATmega for testing & loading of GFX RAM, he is going to eventually have it running from a 65C02. A lot of tech detail in his posts @ 6502.org & demos on YouTube, no schematic yet thohttps://www.youtube.com/channel/UC4iEa96zMzNFfL2VIxlwwMA

author: crispy_tofu
author_rank: Super Contributor
timestamp: November 09, 2015, 08:14:35 am
content: It's so neat!! Beautiful.

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: November 09, 2015, 08:24:00 am
content: Quote from: Moshly on November 09, 2015, 08:13:30 amthanks for the link , get it now .. awesome work in didwell, i wish i have that kind of commitment

author: Psi
author_rank: Super Contributor
timestamp: November 09, 2015, 08:25:34 am
content: He can join the elite group along with the guy who did this

author: Moshly
author_rank: Regular Contributor
timestamp: November 09, 2015, 08:47:56 am
content: That's nuts, +1 for effort, but did that ever work ?Amiga prototype ->

author: tggzzz
author_rank: Super Contributor
timestamp: November 09, 2015, 09:03:11 am
content: If he really is using 74 logic, or perhaps 74LS logic, then with care it might work. The more modern 74 families are progressively less likely to work.But all it requires is for someone th thump the desk, and ...Breadboards: just say no.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 09, 2015, 11:12:48 am
content: It's not as bad as it sounds. The solid metal ground plane saves a lot of trouble.The routes are usually short, which helps a lot; the neatly tied bundles crossing between rows are a bigger concern however. Those hopefully have some VCC/GND wires thrown in with them, to carry the signal currents and reduce crosstalk.The biggest problem with that kind of breadboarding, is getting large voltages (at HF -- ringing) between rows of supply nets. That means you might have a row working okay, but the signals crossing between rows might turn into nonsense.If the GND nets can be returned to GND (shield) frequently, that'll help considerably. But it doesn't look like that would work, since the area is largely solid breadboard.Tim

author: Dago
author_rank: Frequent Contributor
timestamp: November 09, 2015, 12:14:17 pm
content: I don't really know what to think of contraptions like these... I mean kinda cool he had the persistence to spend so much time weaving together that contraption but then again I think of how much more and cooler stuff he would have achieved by not fiddling with breadboard and spending his time with something more productive like design.

author: krivx
author_rank: Frequent Contributor
timestamp: November 09, 2015, 12:16:46 pm
content: Quote from: Dago on November 09, 2015, 12:14:17 pmIt's a hobby project. If you are not motivated by the end result how are you going to do any work? IIRC the author has also done similar programmable logic projects with modern parts, presumably they are not as exciting

author: 6581
author_rank: Unknown
timestamp: November 09, 2015, 12:41:57 pm
content: I totally get the motivation behind these impressive projects. "Because it's there" / "because I can". Everything doesn't have to make sense from the "most effective way of doing things"-perspective. Most complex breadboard project I've "accomplished" had two 555's one 74 series chip - perhaps 20 components. So my mind explodes when looking at something like this. I can imagine that one can learn a lot of unexpected things from a project like this. :-) Me likes.

author: Dago
author_rank: Frequent Contributor
timestamp: November 09, 2015, 12:42:56 pm
content: Quote from: krivx on November 09, 2015, 12:16:46 pmI didn't mean to comment on making something out of logic chips but rather on doing it on a bread board. Like you said making something like that is a hobby and you don't have to have any justification for it. My comment was targeted at making it on breadboard, I just cannot personally see any reason or gain for making it on a breadboard. Just a big waste of time and I don't think (or at least I hope) that anybody enjoys struggling with bad connections on a breadboard etc. or thinks the end result is somehow cooler/better/nicer than actually just making PCBs (or even wirewrap!). Sure you can kinda make it "incrementally" but you could do it as "modules" on separate PCBs as well... Each to their own I guess.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 09, 2015, 12:44:23 pm
content: Quote from: T3sl4co1l on November 09, 2015, 11:12:48 amMy electronics 'A' level product was along similar lines; maybe only 1/4 of the size, but still ridiculous overkill considering what was actually needed to pass the course. Coincidentally, it also used a 6502.The main problem I had with the construction technique was pure ohmic resistance in the power supply. A breadboard connection can have a surprising amount of resistance, and powering 74 series and other non-CMOS devices via a series of plugged connections caused some very odd problems indeed. They all went away when I added some additional, redundant power connections direct from the supply to each individual board's bus bar.

author: krivx
author_rank: Frequent Contributor
timestamp: November 09, 2015, 01:33:01 pm
content: Quote from: Dago on November 09, 2015, 12:42:56 pmActually yeah, I do agree with you. I can see that you can make changes very quickly on a breadboard but it's a nightmare to maintain and document. Personally I could see myself doing sections at a time on breadboards while waiting for PCBs to arrive, I wouldn't want to keep it like that though.I think it is cooler, even if it's just the masochism of it.

author: krivx
author_rank: Frequent Contributor
timestamp: November 09, 2015, 01:45:00 pm
content: Further into the thread the author mentions moving everything to PCBs

author: IanJ
author_rank: Unknown
timestamp: November 09, 2015, 01:53:13 pm
content: I'd heard about this one....found a pic:-Breadboarded ZX Spectrum (ULA re-built using discrete IC's).

author: JoeN
author_rank: Frequent Contributor
timestamp: November 09, 2015, 07:34:52 pm
content: The most complex breadboard I ever did (74LS sequential logic, it scrolls the message on the smaller 8x EPROM using the character set on the larger 16x EPROM), then I gave up on breadboards for anything more complex than quick-and-dirty testing.

author: German_EE
author_rank: Super Contributor
timestamp: November 09, 2015, 09:35:38 pm
content: As somebody who built an Apple //e clone using wirewrap the guys who do this sort of thing all get a round of applause from meWould I do it again? Hell no!!!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 10, 2015, 12:25:55 am
content: Mine back in college,http://seventransistorlabs.com/Images/Z80_Timer2.jpgZ80-CPU at 4MHz, 2kB NVRAM, 8kB SRAM, a little address decoding, 8 IO ports (two octal bus latches for the display -- 8 x 7 segment, multiplexed.. just direct wired, no resistors, 74LS TTL has just the perfect almost-short-circuit current!), 16 bit one-shot timer, two GPO bits, and a parallel port programmer (takes hold of the bus and latches ADDR/DATA bytes into memory).I had it scrolling, blinking and undulating messages on my dorm door. Yes, undulating as in PWM; I had patterns like, text scrolls to left, sinusoidal intensity scrolls to the right. Plus a noise generator (LFSR) on one pin, and a tone generator on the other ( seventransistorlabs.com/Solfeggettio.mp3 ).Tim