6502 serial interface

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Special thanks to these supporters for making this video possible:
Adrien Friggeri, Aleksey Smolenchuk, Alex, Alex Black, An Dương, Anthony Weems, anula, Ben, Ben Cochran, Ben Williams, Bill Cooksey, Bill Watkins, Binh Tran, Богдан Федоров, Bradley Stach, BRian Haug, Burt Humburg, Carl Fooks, Carsten Schwender, Chai, Chris Anders, Chris Lajoie, Chris Sachs, criis, Cristi Cobzarenco, Daniel Jeppsson, Daniel Pink, Daniel Tang, Darrell Burgoon, Dave Walter, David Clark, David Cox, David Dawkins, David House, David Sastre Medina, David Turner, Dean Bevan, Dean Winger, Deep Kalra, Dennis Henderson, Dennis Schubert, Dilip Gowda, Dirk Sperling, Dmitry Guyvoronsky, Dušan Dželebdžić, Dustin Campbell, Dzevad Trumic, Emilio Mendoza, Eric Dynowski, Erik Broeders, Erik Granlund, Ethan Sifferman, Eugene Bulkin, Evan Serrano, Evan Thayer, Eveli László, EvinSaysMarxWasRight!, Florian Bürgi, fxshlein, George Miroshnykov, ghostdunk, GusGold, Hovis Biddle, Humberto Bruni, Ingo Eble, Ivan Esparza, Jack McCracken, Jacob Ford, James Beldock, James Capuder, Jared Dziedzic, Jason Bowen, Jason DeStefano, Jason Grim, Jason Thorpe, JavaXP, Jaxon Ketterman, jemmons, Jeremy Cole, Jesse Miller, Jim Kelly, Jim Knowler, Joe Beda, Joe Pregracke, Joe Rork, Joel Miller, Joey Murphy, John Hamberger jn., John Henning, John Meade, Jon Dugan, Jonn Miller, Joseph Portaro, Jurģis Brigmanis, Justin Graziani, Kai Wells, Kefen, Ken Paul, Kennard Smith, Kenneth Christensen, Kyle Kellogg, Lambda GPU Workstations, László Bácsi, Leo K, Lithou, Lord Dorogoth, Lukasz Pacholik, Marcos Fujisawa, Marcus Classon, Mariano Uvalle, Mark Day, Martin Noble, MatrixSenpai, Mats Fredriksson, Matt Krueger, Matthäus Pawelczyk, Matthew Clifford, melvin2001, Michael Koreshkov, MICHAEL SLASS, Michael Tedder, Michael Timbrook, Michael Weitman, Miguel Ríos, mikebad, Mikel Lindsaar, Miles Macchiaroli, Muqeet Mujahid, NacOJerk, Nate Welch, Nicholas Counts, Nicholas Moresco, Nick Chapman, Oli Homer, Ori Shamir, Örn Arnarson, Paul Heller, Paul Pluzhnikov, Pete Dietl, Phil Dennis, Philip Hofstetter, ProgrammerDor, Ralph Irons, Randal Masutani, Randy True, raoulvp, real_huitz, ReJ aka Renaldas Zioma, Ric King, Rick Hennigan, Robert Diaz, Robert Keown, Robey Pointer, Roland Munsil, Sagnik Bhattacharya, Scott Gorlick, Scott Holmes, Sean Patrick O’Brien, Sergey Kruk, Shane Mulcahy, SonOfSofaman, Spencer Ruport, Stefan Nesinger, Stephen Kovalcik, Stephen Riley, Steve Jones, TheWebMachine, Thomas Eriksen, Tim Oriol, Tim Walkowski, Tim Wheeler, Tom, Tom Knowles, Tom Smith, Tyler Latham, Usseod, Vincent Bernat, Warren Miller, Wim Coekaerts, xisente, Yee Lam Wan

[sefaa]

Babe wake up! Ben Eater posted another video!! 🎉

[jason]

Sat on the kit for a few years, spent the last 2 weeks finally following through the series, I finally finished 30 minutes ago. How delightful to come back to the playlist and find a new episode! Thanks for waiting for me :)

This is such a great series. I showed my 6yo the final build, had him plug it in and reset it, his response: "Wow! How did you make it do that!?" Me: *starts explaining* Him (interrupting): "Can you make it say Hello, Arlo!?". I walked him through the whole process of modifying the program, building, looking at his name in HEX, pulling out the EEPROM, programming it and getting it back on the breadboard. When it printed "Hello, Arlo!" I think a new hobbyist was born.

Then, as I'm typing this, he's in People Playground and calls me over to show me he's put "Hello, Arlo!" on a terminal looking screen you drop into the world. Yeah, he's hooked :)

[fredinit]

Ben... You do an excellent job of explaining both the electronic and software side of this. Not that everyone needs to be a bare-metal programmer, but we need more developers that understand what's going on "under the covers" in hardware. It's been a long time since I did 6502 assembler (back in the computer wars (C=64, Apple ][, Atari .. before the IBM PC!).

[wipoute]

"Be conservative in what you do, be liberal in what you accept from others" - Jon Poster
Man, this is turning into a philosophy channel... and I'm here for it!

[somilamaloyi]

Ben Eater’s videos are too advanced for me now but i still watch because i love watching this whole project form together

[omgwtfkthxbai]

"...and that's what we'll be doing in the next video."

Aww. Just when it was getting to the GOOD part! Please don't make us wait too long, Ben!

[jeromethiel]

The 16550 UART was an amazing achievement. That one chip replaced entire circuit cards to do the same thing.

[JustinRCutler]

You might want to consider the MAX233 (instead of the MAX232). The MAX233 is similar in price, but does not require external charge pump capacitors.

[FragrantVagrant]

If I tried this, I can imagine there being lots of smoke coming out of the breadboard, but man, I love watching this. Thanks, Ben

[MikeF]

It sure is great to really understand the functions of all the terms and protocols I've been using for almost 30 years.

[thewhitefalcon]

It's worth pointing out that Postel's Law didn't work out so well for the Internet. With every implementation being liberal in what it accepts, it wasn't so easy to spot if your implementation had mistakes in what it sent to others, until certain combinations just didn't work at all. Nowadays, we want to have a clear specification and hold all implementations strictly to the specification.

[marianaldenhoevel]

Software person here: I love the order in which you write the code for demonstration. The loop, the if-then-else-logic, and then the body for each case. I vow to steal that when I try to explain stuff.

[DrathVader]

Literally just yesterday I was trying to hook up a COM port on my headless server to a cheap USB UART adapter. Of course it didn't work and I bet it's because I was trying to interface RS-232 level port with 5V level adapter.
Great video and great timing.

[drivers]

I’m finishing up the last kit now (I did the 6502, the 8-bit breadboard computer, and almost done with the video card) and a new kit just came out. Awesome!

[sergeyd]

How many people are out there now who can do this? I deal with Electrical Engineers and Software Developers a lot at my work. The former cannot design a circuit without a CAD simulator, and the latter cannot write an application without C#...
Ben, you are a gem! Hope you have a good employer.

[wChris_]

I believe you can implement send and receive at the same time by using one of the timer interrupts of the VIA chip and handling receive in the Interrupt routine. Sending is done synchronously in the main routine. You can also use the second timer of the VIA for better timing.

[DebuggerKnight]

this guy's talent in reading standards absolutely amazes me

[mikecimerian]

The 6502 is in my opinion the best teaching CPU ever built. People who owned Commodore computers could get into machine language in a few months thank to the kernel built routines. The memory addressing scheme by page memory and offset is simple compared to i386 base address and segment/offset scheme. This is the CPU to experiment and have fun with.

[quentidoudou]

It's almost like Ben heard i don't know how that i'm on my way to build his 6502 computer using his videos..
One again, great job Ben! I'll definitely used that in a while!

[RexxSchneider]

I wish those chips had been around in 1979 when I faced the task of of interfacing a Commodore Pet to an ICL 2960 (I think it was) mainframe in order to download the 1861 census data for a district of Dudley which the mainframe held on magnetic tape. The Pet had no serial interface, so I had to create one using discrete logic and level shifters, and I ended up making one that ran at 300 baud. The database was 'only' about 600K in size, but that took about a day, if I recall correctly, to successfully download onto two double-sided 8-inch floppy disks, in a dual disk drive which was a custom addon for the Pet because the Commodore disks (on the IEEE interface) didn't have enough capacity.