I have the datasheet for the 6522 and I've seen examples here and there online.

But I was wondering if there was a book or even more detailed articles that go into more depth on the 6522? I'm a fan of these "recipe" books when it comes to design or programming and would love if something like that existed for the 6522.

Any suggestions?

Thanks!

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Cat; the other white meat.

It really depends on what you're trying to use the VIA for. The old 6502 Assembly Language Subroutines (Leventhal and Saville) has a section on the 6522 which may prove helpful.

Over the decades, I've used the 6522 for a centronics parallel port with handshaking (Vic-20 days) and more recently for basic parallel I/O and timer support for accurate delays and a RTC in software using a jiffy-counter.... all using interrupt-driven code. It's a fairly simple I/O chip to program.

I've not seen much usage of the serial port with the 6522 as it has an annoying feature (aka bug) that's been written up over the years. Worse, all the manufacturers of the 6522 and later CMOS versions opted to keep it that way. You can always view others' source code that uses the 6522... even the Vic-20 source is out there and that does quite a bit with it, including the RS-232 interface via (no pun intended) bit-banging on the parallel port.

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Regards, KM
https://github.com/floobydust

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

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

Yep, I've read Garth's stuff many times (and will be implementing some of it).


Well, a few different things that I didn't want to flood the board with tons of "how do I do this??" questions.

One such example is that I'm looking for a way to do a simple tone generator like how the Apple II does it.

This is a good example of what I'm looking for:

viewtopic.php?t=342#p2307

I assume the "to hi-Z load" would be a speaker?

Also, I have a few books on interfacing hardware to the VIC-20, C64, etc. They are really good ideas on small projects to implement. So I can look there too. I was just wondering if there was a "6522 Bible" or something like that.

Again, mostly so that I don't have to keep pestering you guys.



Yeah, this is a good point and may mean changing the way I was doing my interrupt hardware. I'm more interested in interfacing with vintage chips. The SD card I'm using is just for convenience. I hope to interface to the 1541 drive, etc.



I've seen that work around. Basically delayed the clock a little IIRC.



That C128-D is worth some money if you still have it. I bought one a few years ago and could literally sell it for almost twice what I paid.

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Cat; the other white meat.

I wonder if there is a good cookbook for 6522 projects.

Here's a book:
Practical interfacing projects with the Commodore computers (1985, Robert Luetzow)

That's exactly what I was trying to ask but sometimes I ramble on. lol

I have a "cookbook for VIC-20", etc. Would be cool if there was one devoted to the 6522. I'm thinking my best bet is to just find these interfacing books and reading through them.

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Cat; the other white meat.

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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?

There is a section about the interval timers of the 6522 in this book:

http://www.atarimania.com/documents/Pro ... iments.pdf

What they managed to achieve out of that Apple II speaker is pretty amazing. I think the record was 5-bit audio, IIRC.

Anyway, yes! That's what I'm looking for. I actually have PB7 free and love the idea of using it to drive a speaker for simple tones. Is there a schematic for that? Or, should I go off the 9-value one we've been talking about?



Yes, I was quite surprised at the lack of dedicated books to the 6522. And you're right...the "Tip of the Day" and "Circuit Potpourri" is great. It's where I've spent most of my time learning about the 6522. Seems there are tons of articles here and there that feature a 6522 but nothing actually devoted to it in print.



Thanks for that! I have dozens and dozens of books in my collection but never saw that one.

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Cat; the other white meat.

Oh! I forgot all about that one. That's a good recommendation.

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

The Apple II audio essentially wired the output of an address decoder ($C03x IIRC) to a flip-flop then to a transistor to drive the speaker. that would be more efficient (ie. less cpu cycles) than a read/modify/write to flip the output of a VIA pin but use what you've got to get going.

I remember toggling the address (read or write - didn't matter!) and watching the speaker cone move in & out (simple things to keep me amused while pouring over the Apple II schematics!)

-Gordon

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--
Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/

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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?

Much heavier? Do you mean driving more than 50% duty cycle? What would happen if I accidentally set PB7 as output and drove it 100%? I know I won't hear audio but I don't want to damage anything.



Yes! This would be fantastic. I know very little about DC circuits and about 1000x less on analog. Would love to see some write ups with more analog stuff.

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Cat; the other white meat.

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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?