Commodore 64 Part 2: Intro to 6502 Machine Language

Using the MOS 6502 and Commodore 64 BASIC as our starting point, I give an overview of how the CPU interprets instructions and how to give the most basic example of writing a value to memory to change the border color with machine language.

[Infinitesap]

This is crazy. One of the best explanations in the world. And only so few pay attention to these three videos. I thank you very much for your effort. I hope you would bring more to the table.

[tach]

Excellent! I could have really used these videos back in the 80's!

[gc]

This explanation was so great. Assembly is not an easy thing to understand, and you made it very clear. Nicely done!!!

[thebootrex]

i just found your channel today and im absolutely loving it! thank you for your concise explanations for someone just getting into this stuff. You are easy to listen to and follow!

[KevinChry]

Thanks for the video. I would sit in front of my c64 for hours writting programs from books and magazines and never knew what I was really doing at time. I always wanted make better programs, but never knew how and information wasn't available like it is now. Just got my C64 back out the other day and trying to get my 1541 back up and running. I also got some parts to build the X1541 cable so good times are ahead.

[LMacNeill]

Compute Magazine had a small program that you could enter and save to your floppy or tape... You’d run that program before typing in one of the programs in their magazine. Each line of the program in the magazine ended in a colon and a 5 digit number. It was a checksum (I know that now — didn’t know that then). The small program you ran before typing in one of their programs would replace a tiny part of the C64 BASIC screen-editor, and would use the checksum number at the end of the line to ensure you entered that line correctly. It would let you know, via a very displeasing “buzz” sound, that you had entered the line incorrectly, so you knew immediately to check that line and correct your mistake. It made entering programs a *lot* easier — and whoever came up with that idea deserved a big pay-raise! Really made my life a lot easier, back in the day.

[AlanCanon]

Love the shout-out to Real Genius! As someone who grew up on the C64, Atari 400, and Atari 2600, I often have been given to wonder why we don't have 64 bit versions of the 6502 today, perhaps a WDC W65C864. The answer is probably, "because Steve Jobs", thinking of his war against the Apple II gs in favor of the Mac.

I've mused about having a 64 bit 6502 descendent and Adrien Kohlbecker, W65C816 maven, has commented in response: it would be in a DIP-40 and they'd make us time demultiplex the 64 bits off the address/data pins.

[FrankEBailey]

I learned much more watching this one video than I ever did poring through those issues of COMPUTE! magazine and typing random examples into my VIC-20.

[adrianpurser]

Great video. This really takes me back to my youth. I had a program published in a magazine when I was a teenager. It also was just a page of data statements. Helped me buy more computer bits :)

[stana]

Is this commodore basic or assembly language. Assembly comes with instructions like Lda, sta etc

[ryan_chapelle]

This series has been great! Keep going, I've learned so much!

[tenminutetokyo]

The $ means it’s a hexadecimal number.

[stacbats]

Nice video. The two so far as well as a machine code book ive been reading have really helped me. Cheers

[AndreasStenmark]

Fun channel :) I grew up on Commodore boxes too. This video perfectly explains how I wrote my first assembler programs, manually converting every single bit. I would also type in those magazine programs and in a retro fit a cpl years ago I dug one out and reimplemented Eliza for Android. Not that it hadn't been done before, but hey...

[rationalraven]

It can be fun to revisit the past for the nostalgia but I'm glad we no longer have to compile assembly code by hand lol

[zaferaydogan]

The C64 used the 6510 whose instruction set was almost identical to the 6502.

[AxelWerner]

really nice tutorial. i wished i would have understood all that back then when i was a kid.

[TheUtuber]

16:37 I think that's red... might need to adjust the hue on the monitor.

[JesusisJesus]

The C=64 has a glitch in the Kernel where if you type 350800 into basic, as if to remove that line from a basic program, the computer jumps to the RESTORE mode. Can anyone please explain this, I've been wondering for the last 35 years.

[RetroMarkyRM]

Nice. I can relate to pretty much everything you´re saying regarding deduction and the complexities of machine language!