Hi everyone, I've been a lurker here for years and am constantly amazed by the quality of the information and advice freely given here. As a fellow enthusiast, thanks for keeping the 6502 so vibrantly alive.

I know the simple prototype blog is probably quite the cliche, and it seems like there are a couple new ones every week. I'm hoping mine will be a little different, and maybe be somewhat interesting. So with that I present my blog: Adventures with the 6502. I'll let the first post there be my introduction. The long and short of the page is the design of a 6502 based SBC from the point of view of a high school student. I'm guessing my breed is fairly rare, I've never seen such a project from another teen (if you have I'd love to see it ). The caliber isn't high, and this is my first real blog, for whatever that's worth.

So let me know what you think, there are only two pages right now. Tomorrow I'll add the current status and some pictures, after which I'll have to wait for some chips to arrive to move forward. I may ask some questions/post updates to this thread as well if they come up.


Thanks for looking!

Will

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

Welcome! This was nice to read on your blog:

What related sites, web pages, books, and articles have you been reading? Even on this site, the non-forum part has a load of stuff that might take some time to find, as you browse the many categories. There's also the 6502 wiki at http://6502org.wikidot.com/, and several forum members have their (our) own related websites.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Hi Garth (I was going to call you Mr. Wilson, but the connotation is a grumpy cartoon character, so maybe not ) Thanks for the welcome and read.

There have been far more than I can possibly recall. The book Apple I Replica Creation by Tom Owad, in combination with obelisk.demon gave me a basic introduction to assembly language, and the former how to decode addresses. I have the 6502 books by Rodney Zaks and have been trying to work on Programming the 6502, but senior work and college applications haven't left many brain cells to spare. It's a bit dense.

I've read parts of your 6502 primer as they become relevant, and it is excellent. Thank you for all your work, it has helped clarify many nuances that aren't as obvious to newbies. Clock phase timing was a big one. I'm also hoping to be able to implement some of your expansion circuits as the core stuff comes together. I look forward to continue reading your site/posts.

I've studied over the weblogs of many of the homebrew projects on the hardware page, and as many simple prototypes I can find here/on the web. Adam Luoranen's computers and his 6502 primer were big. I used the latter to test my CPU's in free run and make sure I was capable of actually accomplishing something. The blinking A15 line was my first big achievement.
I've also perused these forums, and digest everything I can. The Briel computers and AppleFritter forums are some favorites as well specifically addressing the early Apple computers.

I'm trying to remember all the pages I've read, most of the blogs posted here recently. Quite a few data sheets as well. If there's anything in particular you suggest, I would love to check it out. I'm more english oriented than math, so programming is definitely going to be a challenge(and has in the past). But this is a long term project, and I'm quite willing to learn, and am enjoying every bit of it.


As a side note, does anyone know of a decent cad program, preferably for the Mac, that is capable of drawing these schematics? Needs to be free..


Thanks!
Will

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

You're welcome. My sister married a man named Dennis, and when they were courting, he would call the house and my dad would answer, and he would say, "Hello Mr. Wilson, this is Dennis!" I didn't think he was particularly a menace though.


As you've seen on the primer, I don't use CAD for schematics. Even for work, I do them by hand, as every single schematic CAD I've tried has limitations I don't like. I got very proficient at OrCAD at my last place of work, but it had more bugs than an ant hill, at least for intensive users. For work, I have some hand-drawn 18x24" ones very dense with small features all the way across. I definitely use CAD for laying out PC boards though, although I can envision what I'm doing well enough and know the gerber format well enough that I could almost type in a gerber file from the keyboard. I definitely do not use an autorouter, as you cannot get nearly the density with one. A good human will always do a better job than an autorouter.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Haha!



Alright, I have been doing them by hand, but whatever program people here use to do the quick draws for simple circuits looked interesting. No experience at all there, though. Thanks!

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

[quote="wmmullaney]So let me know what you think, there are only two pages right now. Tomorrow I'll add the current status and some pictures, after which I'll have to wait for some chips to arrive to move forward. I may ask some questions/post updates to this thread as well if they come up.

Will[/quote]

I like what I see. sounds familiar, for nostalgia I play with the 6502 like you do. Simple, oldfashioned systems, just for fun to get something working.

You may find that not all 6502 forum users are setting their targets that low. Some will warn you not to use old NMOS 6502 and prefer the uptodate WDC65c02 at as high the clock speed can get combined with FPGA and other modern programmable IC's. That often requires careful PCB design, whole new skills beyond the 6502 and lots of experience in finding timing errors.
. Dont let that discourage going on with your projects. The old 65(c)02 is so easy to work with, at 1 MHz you can get away with nearly anything and get something working and have fun.

The second SBC, withoout ROM reminds me of the OSI300. I once made a copy of that one, a pain to progam, but fun to have a really barebone system.

Hi Hans, thanks for reading.

That's what I find somewhat strange about myself, these old computers and processors elicit that sort of nostalgia. The state of the art when I was born was PPC 601 and Pentium Pro, of which I can very little about. I've convinced myself it's because I'm able to (sort of) understand the functioning on a very low level, a rather impossible task today. If nothing else, they're just plain cool.

I fully understand the disadvantages of running NMOS, but that is the processor that really started the computer revolution, and is in some of my favorites from the time. I'm not interested in high speed, minimal power consumption or potential commercial use, so I'm happy using what I have. Plus, undocumented op codes are a mysterious little adventure. Not to mention most of my chips are pulls from the late 70's, so they all play well together. The WDC chips look nice for the easy DMA application, and I have several Rockwell 6503/65c02, so who know. All part of the fun, and what I can find cheaply.

As for using programmable logic, I remember looking at a cheap Performa Mac motherboard, with its one cpu and three VLSI chips and thinking, this isn't a computer. I know how useful they are, but again, it takes away from the purity of the computer, and why I'm building it, to use super fast comparative supercomputers to support the cpu. Not to mention, it also makes it very hard to understand for newcomers, which is the reason I got into the 6502 anyway.

I couldn't find the OSI300 with a quick search, but it sounds familiar. How did it do DMA? I'd love to be able to do it with the NMOS CPU without a bunch of drivers.

Thanks again for the words of support, hopefully this time I'll get something actually working

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

The CMOS 6502 (65C02) became available in 1983, and we got an announcement of it in '82 when I was in school. I think the initial speed was only 2MHz; but it has all the NMOS bugs fixed and quite a few really good instructions and addressing modes added.

Samuel Falvo (kc5tja who posted here yesterday but has been mostly inactive on the forum for the last couple of years) has a blog post that I think is relevant even though it's mostly about software: http://sam-falvo.github.io/2013/10/06/s ... rvivalism/ . He has a few more related ones indexed at http://sam-falvo.github.io/ .

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Samuel needs to come up with a different photo. The one's he's got there looks like a mug shot.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

I use the geda-project.org suite. You need to install it through MacPorts though so it's not completelty trivial. The alternative is eagle, though I never got on with it but others love it.

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8 bit fun and games: https://www.aslak.net/

See if this helps: http://en.wikipedia.org/wiki/Comparison_of_EDA_software

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Alright, I didn't realize the cmos version was released that early. I might use it (definitely for the dma on the WDC chip), but it seems like the vast majority of code that I've played with is cross compatible. That's what sockets are great for

Wow, that's really cool. Thanks for the link. I need to come up with such a phrase to describe myself, if only to impress the uninitiated

Thanks also for the links to the EDA stuff Aslak3 and Garth, I'll look into it. The first schematics for my use will probably come from a drawing board, since it seems like that is faster than learning this software anyway. Good grief.

Also, I've added another post with a couple pictures to the blog. Sorry they're small, blogger has a large and x-large image size option, one of which is of course too small and the other running off the page. Oh well, you can at least get the gist. I've done my best to describe.

As always, thanks for reading!

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

Hi everyone,

I got the at28C64 chip yesterday, and built an eeprom programmer for the replica I. I'm having a bit of trouble burning the test program in, from the datasheet I was under the impression that it is both (mostly) pin compatible and electrically similar to a very slow SRAM. For that reason, I'm just trying to burn in one byte at a time, but it isn't working at all. All data reads back as $FF, and can't be changed. The programmer works fine with both 8kb (seemingly the same pinout as the rom) and 32kb ram chips. I'm confused, am I missing something obvious? The Atmel rom is brand new, with a 2012 date code.

This is very frustrating, I have everything else assembled and ready to go. If it doesn't work, I think I'm going to try to hack a 3v ram chip and a battery to make a nonvolatile rom substitute. Tired of waiting for shipping..


Thanks for any help.

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler

Hmmm.. one thing I notice in the Atmel data sheet's fine print under 4.6.1 Hardware Data Protection -- "holding any one of OE low, CE high, or WE high inhibits write cycles." Is that a useful clue? For example, are you holding OE low? I think most RAMs will accept a write with OE low, but evidently the 28c64 will not.

Maybe it would help if you described your programmer and how it operates.

-- Jeff

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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

The programmer is described here: http://www.brielcomputers.com/phpBB3/vi ... p?f=5&t=56

All the enable lines are dynamic, non are held. The datasheet doesn't have many details on the feature, but I assume this satisfies requirements. Everyone in that thread seems to have good success with it, so I'll check over my connections again then assume the chip dead I guess..

Side note, is the 6502/C02 capable of working with 3v logic signals? The low voltage ram I have accepts 5v signals, but sends 3v. These would be a lot easier to make nvram with.

Thanks!

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Adventures with the 6502 - Simple 6502 computer projects from a high schooler