Building a 6502 computer: Episode 2, the pins of the 6502 and connecting for a basic system.

[@knghtbrd]

"4. I want to, so there." is the best reason to do any project. Ever.

[@builderdev212]

I love this format! You’ve explained things that I’ve never even heard of before in a way that made sense to me. I might end up buying my own and following along with this!

[@XTronical]

Brilliant, yes please follow along.

[@Rich-can-do]

I love where this is going. I also adore writing in assembler language. This reminds me back to my Amstrad CPC 464 and the green screen I had. I was amazed at how much they can do with so little. Grass roots back to basics. I love it!. Ty for sharing.

[@canuckprogressive.3435]

I have been playing with this cpu for maybe a year and have the datasheet. Your in depth explanations of the pins are giving me a little more insight into some of them. Thank you.

[@bjorntheviking6745]

6502 asm will never die

[@Rich-can-do]

I am building Ben's computer too. and I also have I think all the bits to make a Z80 one. I have Z80, PIO and SIO and static ram 32x8k and some at28c256, and the smaller 64b versions. I just need more breadboard. I am glad i have stumbled onto your guide. I like what I see.

[@Anticitizen666]

About the bar above an active low pin. In most schematics and datasheets I've seen (and created) the / is used to denote active low. like "/RESET". I have also seen lower case "n" also used (for negative), so "nRESET"

[@XTronical]

Thank you for further information.

[@alnoorratansi9364]

Hope you do more videos on this topic

[@XTronical]

Thanks, next one in around 2 weeks.

[@canuckprogressive.3435]

I found the vector pull pin quite usefull. I hooked it up to a max 708 chip like the one I used for power on reset. I hooked the output of the chip to an led. Now I can see if things that should trigger an interrupt, like using my hex keypad, actually do trigger the interrupt.

[@XTronical]

That's a really useful tip, thank you

[@tonyfremont]

I'd really like to have been at the meeting where the SOB pin was justified. The output clocks are slightly delayed by the push-pull amp and inverters. I also heard they are shorter than you'd expect so that they never appear overlapped to other circuitry accessing the bus. This would mean that they can both be concurrently low for short periods before a rising edge occurs. Maybe you could show us on a scope?

[@XTronical]

Thanks for your comments, bit late on this reply but I will look at this next time perhaps

[@5ch4um1]

Interesting video! And since you mentioned OpenOffice, in LibreOffice Writer you can just ctrl-select all the text you want to have an overbar, then go to Format/Character/Font Effects and select from the various types of overlining.

[@XTronical]

Ahh, I've got that installed on my Linux box. That sounds perfect, thank you.

[@knghtbrd]

@@XTronical Even better, LibreOffice has such a customizable UI that you could create a button for it and stick it right next to the underline if you wanted to. OpenOffice is basically dead at this point, it is in mothball maintenance mode where the minorest of changes get made every six months or so resulting in a "new release" while the OOo fork LibreOffice is where all development really happens. They're both kind of a disaster owing to MSOffice compatibility mostly, but they work well given those limits, and you don't need to insert field codes to specify the text as an equation with an overline.

[@XTronical]

Good to know

[@63801170]

@@XTronical In MS Word you could use the “equation editor” by placing cursor where needing the pin label. Press Alt + '=' and the equation editor pops up. Type in the label code (eg. VP), select the text, then in the ribbon/menus choose the Accent button option. A window appears to select the type of ‘accent’ and there’s one with a bar above the letter/s. Choose this and then you have the bar above, but you might want to set the default italic font back to plain (in normal Home menu options). That’s it 😎. It can be in-line with other text if describing the label, or in a text-box floating next to a diagram, etc. NOTE : The first time loading the accent options may be slow, then it’s retained?. Also, there’s probably a way to stop equation text defaulting to italics, but I haven’t done so.

[@metalhead5858]

Hi, I cannot find episode 1 can you send me a link

[@XTronical]

kzbin.info/www/bejne/jKPSXoeIba2Waacsi=S-SVo-jCLRGGwJLF

[@canuckprogressive.3435]

Reason 4 is the best one. It is my reason too.

[@canuckprogressive.3435]

Another reason is I can't stick a modern 8 core Intel CPU on a breadboard!

[@mikehaas543]

Just a note PHI2O is a very important for timing it is delayed a bit to make timing for memory and peripherals access to reduce race conditions. By the way the original 6502 the PHI2O was not driven real hard and buffers were used to increase it's ability to drive more devices. hope someone finds this useful while building their own computer...

[@XTronical]

Thank you your comments

[@PhyChris]

68k next. its only twice the bus wires... right? :)

[@vanhetgoor]

It took me a while to find out what you mean with "BAR" my first idea was some sort of a saloon where cowboys get an alcoholic beverage. Second guess was something with the power rail. Balet and computing are like things from another galaxy. Negative logic is noted down as "NOT" when there are no overscores possible.

[@XTronical]

Yes, it's western design centre that have decided to use B for bar to mean bar line , I don't like it.

[@vanhetgoor]

@@XTronical Well, that is a good point. If Wester Design say so then who are we to worry them. Without Western Design, both the Cyberdyne Systems Model 101 / T-800 and Bender are without brains!

[@XTronical]

Ha ha, brilliant, you know your 6502 reference. Futurama was Brill.

[@TexasGit]

Sometimes, !VP would have been understood as well.

[@XTronical]

True, and that actually makes a lot of sense if you've coded beyond possibly BASIC.

[@canuckprogressive.3435]

One sight critisism I have is your audio is kind of boomy and not all that clear. Is your room echoy? Maybe a better mike would help?.

[@XTronical]

I use a good quality blue nano. But the room is not ideal.

[@geos_one]

the audio is really annoying it sounds like you are sitting in an big empty garge, but the video is great.

[@Spined]

I've heard way worse. Compared to many others his audio quality is in the top 10%.

[@f-73p21]

Perfect timing. I've started building Ben Eater's 6502 computer and recently posted an unboxing video: kzbin.info/www/bejne/fILbhWdnrsl4fK8.