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How to interface speaker to 6502? [message #7763]

Sun, 07 June 2020 17:30

ashtons
Messages: 8
Registered: May 2020
Location: Louisiana

Junior Member

Hello.

Right now I'm trying to figure out address decode logic for a project I'm working on, which is supposed to have a simple speaker of some sort (I haven't figured out the exact model speaker as I don't know precisely what I should look for), and I realized that I don't know how to interface said speaker to the processor I'm using in this processor, a 6502. I have some assumptions (that involve a Digital-to-Analog Converter) but I'm not entirely sure if they're correct or if it would apply to just any speaker I choose.

(I'm partially worried that this sounds dumb but I am legitimately unsure.)

[Updated on: Sun, 07 June 2020 17:31]

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Re: How to interface speaker to 6502? [message #7787 is a reply to message #7763]

Sun, 14 June 2020 17:24

etchedpixels
Messages: 333
Registered: October 2015

Senior Member

Better place to ask might be 6502.org but you probably want to grab some of the old books on the subject and/or read and play with

http://wilsonminesco.com/6502primer/

http://searle.x10host.com/uk101/uk101.html

The audio side can be a D2A convertor, a single bit driven by the CPU or a sound chip that does all the work. Most of the 6502 home computers used sound chips as they were primarily game consoles.

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Re: How to interface speaker to 6502? [message #7789 is a reply to message #7763]

Mon, 15 June 2020 09:18

drogon
Messages: 2
Registered: February 2019
Location: Scotland

Junior Member

ashtons wrote on Sun, 07 June 2020 17:30

Hello.

Right now I'm trying to figure out address decode logic for a project I'm working on, which is supposed to have a simple speaker of some sort (I haven't figured out the exact model speaker as I don't know precisely what I should look for), and I realized that I don't know how to interface said speaker to the processor I'm using in this processor, a 6502. I have some assumptions (that involve a Digital-to-Analog Converter) but I'm not entirely sure if they're correct or if it would apply to just any speaker I choose.

(I'm partially worried that this sounds dumb but I am legitimately unsure.

the simplest way would possibly be the way the Apple II did it (google for the schematics), but in essence an address was decoded and that signal fed into a flip-flop with the output directly to the speaker (via a buffer transistor IIRC).

You then had to make timed loops in software to make tones, or use a 1-bit PWM audio system that was latterly used, but this requires RAM to store the data and very precise timings.

There are/were sound chips of the era - these you programmed the frequency, amplitude and duration into - some were cleverer than others. See C64 and BBC Micro descriptions for example.

If you're looking for a more modern way, then remember that samples eat RAM and you generally don't have much on the 6502...

-Gordon

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