A 6502 Based Computer on a Single Breadboard
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- เผยแพร่เมื่อ 1 ม.ค. 2023
- In this video I build a complete 6502 based computer on one breadboard using the 28 pin 6502 version, the 6507.
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In the next video I show how you can use #i2c to control thousands of different peripherals - and make an Arduino-like PCB for it!
• I²C on a 6502 Single B...
Source code and schematic: github.com/AndersBNielsen/650...
My mentioned videos:
MS Basic on a 6502: • Microsoft BASIC from 1...
My sub-20$ 6502 computer: www.youtube.com/watch?v=7Sufp...
My video on the 6532 RIOT: • The amazing 6502 suppo...
Fixing an IBM 5160 MB: • Fixing an IBM PC XT 51...
Credits:
Lot's of 6502 stuff on 6502.org/
Ben' Eater's SUPER educational 6502 series: eater.net/6502
Garth Wilson's 6502 Primer that Ben used(and anyone building a 6502 project should check out): wilsonminesco.com/6502primer/p...
Fair use clips from "Close Encounters of the Third Kind - 1977, renewed 2005, 1980, 1998 Columbia Pictures Industries, Inc. All Rights Reserved."
Atari 2600 photo
Evan-Amos, Public domain, via Wikimedia Commons - วิทยาศาสตร์และเทคโนโลยี
Oh, so this is what a single board computer is.
I've never heard of the 6507 - and I'm old! :)
I've never used those Riot chips before but they seem interesting! Thanks Anders!
As you said the 555 IC can blink a LED, but with the button shorted a resistor in the timing circuit the 555 IC also can do what your program does, two different blinking rate. But for example blinking an SOS Morse code is not possible with the 555 IC but you can code it in your 6502 based program. Sorry for my poor English.
Good point :)
Thank you for making this vid! The RIOT is truly a lifesaver chip in this case xD. I also got inspired by your 65uino project and is in the process of making something similar except with a 6502 40dip. I guess it'll be more similar to Ben Eater's 6502 but Uno-sized.
You’re welcome! New one coming soon.
I have a feeling you’ll find that you need to switch to SMD for the rest if you want to fit a 40 pin 6502 in an Uno form factor :)
Impossible to fit more than one 40 pin dip if you also want to fit a third 28-40pin DIP.
Great video, especially leaving in the debugging part.
This is an interesting take on the 6502 breadboard PC :)
Amazing project! Well done
Congratulations Anders!
Great video as usual. Thanks!
what an amazing project!
A 6532 based 6502 system is so simple! My compliments for this video and design!
Would a larger 6502 and a smaller 28C16/64 EEPROM be possible too? 6507 are rare nowadays.
Maybe a 24 pin C16 and a 6502 would barely fit - maybe by using the crystal oscillator in the schematic instead of the can since that takes up more space than it should. Otherwise you’d still be two pins width short, as I already already use the whole width.
@HansOtten as in, retro.hansotten.nl/6502-sbc/ ? If so, thank you very much for that resource!
Also - the 6507 seems plentiful in the Asian markets. I think I only had to pay 1-2$ :)
They're available for £1 on AliExpress.
I'm particularly excited by all the Yamaha FM Synthesis chips for a pound on AliExpress 😁
@James, me too :D
Thank you for another nice video, Anders. Can you add a schematic in PDF format on your GITHUB, please?
I just uploaded the PDF to the hardware folder on Github.
Don Lancaster was a wise man, it was nice that you quoted him.
I was sad to hear he passed a few months after I said that. I would've loved to have a talk with him about pretty much anything.
Darn near got a 2600 on a breadboard, there.
I'd like to review this SBC. But not sure if the browser video playback would be good enough for my subscribers 😅And can it play Xonotic?
Nice job to get this working. My hat goes off. Greetings.
In that case I suggest you make your own - instructions provided in the video and Github :D
Xonotic might require a RAM upgrade of a few orders of magnitude from the current 128 bytes XD
6507+RIOT is 2/3 of an Atari 2600!
oh lol, you got there at 19:57 😂
Can the RIOT memory mapping be changed? Would not be great if it's fixed at 0x80..., cluttering the zero page
Like I said in the video RS can be connected to A9 to put only RAM in zp + stack(like the Atari 2600). But with I/O in zp you get faster I/O and there’s only RAM enough for half of zp anyway.
Neat. Of course, with only 4k bytes accessible in the ROM due to the limited address space and simple decoding, you could have saved two more pins in breadboard length by going truly retro and using a 2532 EPROM instead of the 27512 monster. 😀
Indeed :) I used the w27c512 because - strangely - they are cheaper and I have a good bunch of them... And I don't need a UV eraser. I really wish I had a box of '70's PROMs...
Hi 👋 cool project.But can we use 6522 as i/o port and not 6532. And for example, if we need to connect ram?
Sure you can :) The limit of "on a single breadbord" if pretty arbitrary but if you use the 6522 you will end up needing a second breadboard for RAM and change the address decoding of course.
Like the Garth Wilson's 6502 potpourri @ wilsonminesco.com
@@AndersNielsenAAThank you. I missed 1 month without seeing what you wrote
Awesome, think you can do it with a z80?
I think I'll need a bigger breadboard if I don't start stacking IC's :)
Huh, RIOT chips seem useful!
You should consider socketing the bigger ICs here for ease of changing them. At least the EEPROM?
A breadboard really is one big socket ;-) I've wired it so it's pretty easy to pop out the ROM. Most of the development for this board I'll probably be testing on my 6502SBC r1 though, since that'll accept code wirelessly.
@@AndersNielsenAA huh. How does that work?
Also, went and looked up the RIOT chips. It seems there was a variant with ROM too, RRIOT. Unfortunately, it is mask ROM, not EPROM/EEPROM. So no reprogramming it… only whatever the original program on the chip was.
@@chexo3 That’s the 6530 - what MOS used in the KIM-1 :)
I made another video on the wireless interface of my SBC r1.
Where do you buy old MOS chips? Ebay?
There's an almost infinite amount coming out of Asia from recycled consoles, industrial control boards etc. The 6507 I use here with the Rockwell branding is from 1988 and probably came out of some industrial unit.
More specifically: You'll find a lot on Aliexpress or Ebay.
Gracias
De nada!
What's the movie in the beginning, didn't quite get the title
Close Encounters of the Third Kind
Nice, i suscribed
Big Apple II vibes, or a modern version of the Heathkit MCU kit (although 68000 based)
I really wish I could've played with an H100 kit :)
@@AndersNielsenAA I still have it 😎
@@prometheus4130 Oh the envy! :D
New subscriber!
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How thick are those cables?
23 AWG.
Why not do it on perforated proto breadboard with a wire wrap tool? Tehn you could the the full compliment of components with the same amount of holes as the solderless breadboard and probably more relible aswell.
I always thought wire wrapping was none of the fun for the price of even more work and well.. price. Those tools are expensive!
It gets points for being “era correct” but I have to admit that my next step after the breadboard - if it’s more than a handful of connections - is to order 5 pcbs for almost no money and have them delivered in a week. If it’s one or two dip14’s I’ll happily grab a radio shack protoboard - no tools needed.
And if it’s really about size we can always emulate everything in a modern MCU or FPGA in a BGA package and call it a day - but wouldn’t that be boring :)
@@AndersNielsenAA It would be boring indeed. I remember when a company I helped out in was prototyping a X-ray/Laser bone density meter andthey had bought a wire wrap gun, And indeed it was expensive. I heard someone on youtube say it wasnt the other week though so I thought maybe they chinese had come up with a remedy for that. My thought was mostly because my solderless breadboards are so unbelievably unreliable in their connections. These days there are probably farts with more computing power than a 6502 that you could emulate them with if you wanted to be boring.
@@rimmersbryggeri There are some horrible breadboards out there - the ones I use now are great but some are basically single use. Ben Eater even did a video on how different they can be.
@@AndersNielsenAA I think Mr Carlsons lab did a breadboard video also. But the internet makes it so difficlt to buy consistently since you may not get the same item even if you order the same item from the same source, very annoing indeed.
@@AndersNielsenAA Wire wrapping was very much used to build prototypes about 30 years ago.I once watched a customer building a 80286 board for a Telecom device. He had no schematics or drawings. Just wiring from his own memory. Personally I have built many 8039 and 8051 boards using wire wrapping back in 1987-94.The back plane on a
DEC VAX 11/780 was also wire wrapped. I have done a lot of mods on the 11/780 using OK tools and later invested in a Vero electrical wrapping gun.
The Atari 2600's only built in RAM was 2 RIOTs. 64 bytes for page zero and 64 bytes for stack.
Actually only a single RIOT :) I mentioned it in the video - by connecting A9 to RS of the riot, RAM was available to both zero page and stack. So they both had 128 bytes - the same bytes though.
hm. how about no eeprom, instead just sram loaded from i^2c then run. forth can be coded in < 1k
I've been thinking about a few no-ROM designs - with and without battery backup. Since holding an NMOS 6502/6507 in reset for a long period of time can damage it - I've heard - loading the RAM without bus contention becomes the issue. Then it needs 24 bits worth of bus transceivers "n stuff" :/ A 65C02 with a BE line is a better candidate though.
@@AndersNielsenAA Holding it in reset doesn't damage the chip, but its registers are basically DRAM cells and will not hold data very long without the clock. Very few microprocessors used static memory registers and could be clocked down to 0Hz, but the 1802 was one of them.
As for the original question, what is listening to i2c, and/or where do you get an SRAM chip with both a parallel and an i2c interface?
@@8bitwiz_ I’d like to see that i2c device too.
Beware of holding down rst on a 6502 though - some do have a bug.
Quoting Garth Wilson about the bug from his RST site: “Now if you really must use an old NMOS 6502 (I don't recommend it), you should be aware that some NMOS 6502's had an internal heating problem that could damage the part if the reset line was held down very long. It is recommended that you not hold it down more than about a tenth of a second.”
@@8bitwiz_ There is an Apple I board out there using Arduino Nano as interface. I have the board but not built it yet.Gary Evans also has a project on TH-cam using a Raspberry PI Pico as program loader/interface.Other people have used Atmega 644 and Atmega 1284P. I have also seen a PIC18F46xx to load code into RAM and boot a 6502. My plan now is to learn a PCB Cad program so I can design boards and send the Gerber files to China and have the boards made. A board using Motorola 68000 has also been on my to do list for many years but too much wiring. A ready made board could also be used if I found one.
Doesn't that make this an Atari 2600?
A 2600 didn’t fit on a breadboard and this is missing a TIA - but like I mention at the end of the video, we’re close :)
It's funny how the random numbers for ICs won't make sense if you don't have electronics experience.
I still remember when they were all nonsense and I didn’t even know what to google :)
rom and ram pinout is same you can stack them and bend 1 or 2 pins to make them work. better do it for ram
They stack just fine but require additional address decoding :)
128 bytes was fine for the Atari 2600 and I have a feeling I can get a lot out of it too ;-)
You can insert TIA on second breadboard and you will have working A2600
Indeed. I chose a different way though - and got 128x64 characters instead :)
Nice build. Doom video when?
I think I’ll have to put my own spin on Doom to make it fit.. Doom 2D?
Can i use it as a pc
People used hardware like this as a PC in the 1970's
@@AndersNielsenAA how to connect mouse,keyboard and monitor and how to install operating system
You can connect a keyboard using a ps/2 to parallel adapter but with the 6507 you will need to poll the keyboard port since the 6507 doesn't have hardware interrupts. Monitor will need a video card. You'll probably get the idea from "My 6502 SBC R1 complete hardware overview" video.
Due to limited RAM you probably want to write your own operating system depending on what you want it to do.
try pentium 100MHz fast cache chip based rom alu logic
yes load the fast cache memory from rom
You want me to interface a ROM to a 273 pin Pentium, essentially making a chipset? Not sure I follow your suggestion but sounds interesting.
@@AndersNielsenAA dont include a pentium chip, only external cache chips (for pentium) that run at 100MHz
@@AndersNielsenAA the cache chip is much more simpler (as memory chip) than the pentium itself, use the cache memory chip as the processor core itself, ie rom alu fast result storage, the cache is the alu, like in old 8-bit machines
@@AndersNielsenAA you can fit various 8/16 bit float operations (single or dual argument) in one cache chip
You can get much larger breadboards. Just sayin'
You can also get smaller components :) This is absolutely one of those “because you can” things.