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PostPosted: Mon Jul 12, 2021 5:39 pm 
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Ben Eater's design-and-build videos are very popular, and I imagine a lot of people have followed his lead and built a first 6502 system. Some people might have started, and got stuck, and some might have finished, but find things don't work, and some will have been completely successful and then wanted to go further.

All 6502 related questions and projects are welcome here, in all those categories and more.

This post aims to put down a few pointers for how to use this forum and how to make progress.

First off, we're all friendly and prefer politeness, so please be family-friendly. It's better to say that you're struggling with something than to say that thing is terrible and ill-conceived. You might well find that the inventor is among your readers - no need to cast aspersions.

Second, there are many helpful and experienced people here, who are not all of exactly the same mind. So you will see some variety in preferences and approaches, and that's fine. There's usually no one right way to do things, and if some ways are fast but risky and others are slow but sure, it is a matter of preference which way to go.

But we have learnt a few things, in the projects we've personally built and in those whose progress we've followed.

One is, that enthusiasm is helpful and discouragement is to be avoided. As a consequence, it's better not to be too ambitious, and to proceed step by step. It's common enough to want to build a fully featured system and to get bogged down in adding new ideas, before building a solid core as a foundation. Your first system, or your second system, isn't likely to be your final system, so long as you don't get discouraged, so there's no need to try to do everything all at once.

Another, is that debugging is something of an art, or at least a craft, which benefits from experience. Taking care is a good way to proceed: take care to know what it is you've made, and what it is you've seen. Take care to describe your problem: what you expected to see, and what you did see. And take care to double-check your work, even if you think it's all correct. If everything seems right, but the thing doesn't work, well, evidently something is in fact wrong! So, doubt everything, generate hypotheses, take notes, and change one thing at a time.

When you're stuck, start a thread, describe what you're doing and what you see. When you get responses, read them carefully. Skipping over text is a big cause of things taking longer than they need to.

Skipping over text is a big cause of things taking longer than they need to. (Just testing.)

Also, there are thousands of topics here already, and others may have seen what you've seen or be trying to do what you're trying to do. Be sure to search, either using the forum search or using your favourite search engine.

We, the regulars and existing members, want to see you succeed, whether it's a hardware build, an extension, or a software problem. Ideally you'll find this is a good place to be, and will get ideas for further projects.

There are some major topics on this forum which will be of interest, which I might add here as links or others may give links in this thread. I'll give just two or three pointers here:


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PostPosted: Tue Jul 13, 2021 12:59 am 
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It's worth mentioning that the eater's design is a verbatim copy of the design that Garth Wilson had generously shared well over a decade ago. Unfortunately, I don't think Garth was ever credited.

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PostPosted: Tue Jul 13, 2021 1:50 am 
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I think this is a good topic, but should also be linked in the Newbies section for obvious reasons.

Beyond being a copy from Garth's primer (the internet bible for 65xx newbies), Ben tends to explain circuitry reasonably well, but is completely absent on critical areas. i.e., how you take a design and implement it into a properly functioning circuit that can be implemented by anyone.

Perhaps a follow-on to this topic would be areas that should be sorted out, like the reset circuit... proper power supply and bypassing. Also, a simple warning to those who buy the kit... having it work reasonably well doesn't make it the perfect candidate for a PCB layout... there's more to it.

I think Garth mainly did a wire-wrap of his basic circuit. And with the older NMOS and LS parts, it worked fine. Using different parts requires some changes, but these are likely beyond the folks that are buying his kit, which is why several of them end up here, looking for help.

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PostPosted: Tue Jul 13, 2021 3:12 am 
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Perhaps he is good at explaining Garth's circuit while passive-aggressively bullying you into thinking he is so smart and organized and coordinated. The workbench is clean, everything just works, and is so pretty! You try it - and your circuit is glitchy and you can't find the parts on your messy desk, and wires keep falling out of your breadboard. He must be so intelligent! I better buy his kit, or a book or whatever.

Women's magazines push an unattainable standard of thinness and beauty, making women feel inadequate; quick-fix beauty products and diets are available for a price. A self-doubting customer is the best customer. Today's version is projecting a bull**** 'movie' version of yourself and your hobbies on social media. What a bunch of ***wipes.

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Last edited by enso on Tue Jul 13, 2021 4:07 pm, edited 2 times in total.

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PostPosted: Tue Jul 13, 2021 3:14 am 
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floobydust wrote:
I think Garth mainly did a wire-wrap of his basic circuit. And with the older NMOS and LS parts, it worked fine. Using different parts requires some changes, but these are likely beyond the folks that are buying his kit, which is why several of them end up here, looking for help.

On the main board, it's all CMOS except the data converters, their op amps, and the RS-232 line drivers and receivers. On the mezzanine, the speaker amplifier is an LM386 [Edit: it's an LM380, not 386] (non-CMOS), but the two logic ICs I'm using for the 65SIB are an 'HCT139 and an LM339 comparator (the latter not being CMOS). The glue logic on the main board has one 'HC74 and one 'AC14. With 4MHz CMOS processor and VIAs and ACIAs and 70ns memory, it begins to fail just a hair beyond 7MHz, so I run it at 5MHz for some margin.

The first liability in the build quality is not the wire-wrap, but rather that I did not use perfboard with a ground plane. I understand this stuff a lot better now than I did when I originally built it. WW has the advantage that the wires can make the shortest possible connection, at any angle, and you can also run them very close to the ground plane if you have one. Since routing is not a problem, you can put the sockets shoulder to shoulder with no space between them, and get the whole design down smaller, meaning the maximum connection length is pretty short, without worries about not being able to route something. You can also get perfboard with planes on both sides, and use the second one for power.

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PostPosted: Tue Jul 13, 2021 5:53 am 
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floobydust wrote:
Beyond being a copy from Garth's primer (the internet bible for 65xx newbies), Ben tends to explain circuitry reasonably well, but is completely absent on critical areas. i.e., how you take a design and implement it into a properly functioning circuit that can be implemented by anyone.

That is my principal beef with Mr. Eater's presentations. In what may be a misguided effort to "dumb down" the building of a 6502 contraption, he leaves out details that are very much part of the picture. Those who view his videos, try to duplicate what they see, and don't realize they don't have all the information needed to get a unit running, end up becoming 6502.org members. :D

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PostPosted: Tue Jul 13, 2021 5:59 am 
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GARTHWILSON wrote:
The first liability in the build quality is not the wire-wrap, but rather that I did not use perfboard with a ground plane...You can also get perfboard with planes on both sides, and use the second one for power.

With multilayer PCB prices have tumbled quite a bit in the last several years, wirewrapping on a perf board with planes isn't as attractive as it once was. That said, wirewrapped units are definitely easier to modify, which can be very useful in prototyping. In years past, I did a lot of prototyping with wirewrap, as well as point-to-point with soldered leads, using 30 ga wire. That, of course, was back when I had decent vision. :cry:

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PostPosted: Tue Jul 13, 2021 6:25 am 
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There is something very enjoyable about wire-wrapping. I strongly recommend it - it's worth the $50-$100 or so to build the first board. If you use a perfboard with a ground-plane the results are pretty decent. And you can have your board up and running in an evening, which is better than days or weeks for cheap PCBs.

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PostPosted: Tue Jul 13, 2021 6:38 am 
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enso wrote:
There is something very enjoyable about wire-wrapping. I strongly recommend it - it's worth the $50-$100 or so to build the first board. If you use a perfboard with a ground-plane the results are pretty decent. And you can have your board up and running in an evening, which is better than days or weeks for cheap PCBs.

I got my workbench computer in its original form built and running in a week. I have added a lot to it since then (which is one of the values of WW—you can augment and modify. Unfortunately, yes, it has lost the economy of scale, since it is done by so few people now.

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PostPosted: Tue Jul 13, 2021 7:15 am 
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We do seem to have got ourselves into a bit of a local minimum here, when it comes to letting off steam. Unfortunately, too many of those posts and it starts to make a new normal.

It's fine, and normal, to be grumpy sometimes. But it's preferable not be grumpy all the time, or to be grumpy online too much.

It seems especially unhelpful, to the future health of the forum, to use a welcoming thread as a place to complain.

Can we perhaps try, collectively, to do more by way of sharing our enjoyment of our interest in 6502?


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PostPosted: Tue Jul 13, 2021 7:48 am 
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enso wrote:
It's worth mentioning that the eater's design is a verbatim copy of the design that Garth Wilson had generously shared well over a decade ago. Unfortunately, I don't think Garth was ever credited.

Actually, Garth's addressing scheme has been public knowledge for some 20 years. There is a post about it somewhere around here. I recall reading it when I first started lurking here around 2007 or so.

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PostPosted: Tue Jul 13, 2021 7:50 am 
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BigDumbDinosaur wrote:
enso wrote:
It's worth mentioning that the eater's design is a verbatim copy of the design that Garth Wilson had generously shared well over a decade ago. Unfortunately, I don't think Garth was ever credited.

Actually, Garth's addressing scheme has been public knowledge for some 20 years. There is a post about it somewhere around here. I recall reading it when I first started lurking here around 2007 or so.

Yes; I forgot that I had put it in the Tip of the Day column in Jan 2001: viewtopic.php?p=2326#p2326

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PostPosted: Tue Jul 13, 2021 4:13 pm 
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Wire wrapping is actually pretty cheap. You can pick up the tool for $20 or so, and the wire is not that expensive. You can use inexpensive machine-socket strips for DIY sockets or pick up surplus ones over time. I make my own sockets on a 3-D printer. Ground-plane perf board is hard to come by cheaply, but even without a ground-plane wire-wrapping works ok. I have a 10MHz W65C02 system running without a ground-plane.

Even cheap PCB houses, with shipping, will charge you $30 or so per order.

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PostPosted: Tue Jul 13, 2021 5:36 pm 
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enso wrote:
Wire wrapping is actually pretty cheap. You can pick up the tool for $20 or so, and the wire is not that expensive. You can use inexpensive machine-socket strips for DIY sockets or pick up surplus ones over time. I make my own sockets on a 3-D printer. Ground-plane perf board is hard to come by cheaply, but even without a ground-plane wire-wrapping works ok. I have a 10MHz W65C02 system running without a ground-plane.

Even cheap PCB houses, with shipping, will charge you $30 or so per order.


I did a lot of WW back in the 80's. Here is one - it's a 6502 that ran at 2.5Mhz:

Attachment:
6502back.jpg
6502back.jpg [ 229.8 KiB | Viewed 1613 times ]


However when I came to do my Ruby system I looked at WW again and was quite shocked. The bit of board I used then is still available - for about £45. Then the sockets with square pins are not cheap either, then the wire and finally - back then I used a mains powered 'gun' that did strip and wrap in one go - that is close to £500 now.

And so no wire wrap. I went back to my old favourite, Stripboard when I moved my 65C02 from breadboard.

I'm running at 16Mhz on both Stripboard and double sided PCB, 65C02 and now 65C816.... It's been stable for a very long time now (would have had an uptime of nearly 3 months if I'd not had to power the house down a couple of days ago to change some mains sockets!) and I'm glad I don't have the test kit to tell me it shouldn't be working ...

So I just say "go for it".. Use the technology you're most familiar with. Breadboards are good for a few Mhz and much faster if you take care (e.g. VGA is possible at 25Mhz) but what's a weeks wait for a PCB? Not a lot in my book...

-Gordon

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PostPosted: Tue Jul 13, 2021 6:58 pm 
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True, a week (or more like three weeks) is not that long. But my ADHD does not work well with that, and I am six projects in by then. I can't remember the details, and haven't been able to take notes that work well enough (and I've been trying for decades). So I wind up spending a day catching up on something that was obvious at the time, and sometimes drop projects because by the time I get the PCB I don't care enough to bother...

Another problem I encounter is that a few days after sending in the order, I realize that I made a mistake or want something different. Once I wound up two design changes ahead. With wire-wrapping I can make changes immediately.

I try to save the PCB for last, after all the design issues had been addressed. With breadboards and ad-hoc solder joints I kind of have to make a PCB. With wire wrapping, the prototype is good enough, and the PCB is there if I need a few extras.

Boards with ground plane are expensive, but if you calculate how many good quality breadboards you would need for the same number of ICs that would fit onto a perfboard, it is still a bargain.

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