TAG

Controlling real chips with Retrocade synth

Recommended Posts

While digging into the retrocade project I thought about how easy it would be to control real chips, since the HDL chips are implemented with the same interfaces as the real chips it seems to me that it would be very simple to modify a SID peripheral for example to just connect the interface signals to IO and drive a real chip SID.  It would be a great way to compare the real thing to the HDL versions, and a way to use real chips if you had them.

Share this post


Link to post
Share on other sites

yes, it would be very easy to do, in fact when I was designing the RetroCade board I had considered adding a socket for an original SID chip...

 

Jack.

Share this post


Link to post
Share on other sites

Just don't forget to put some level shifting between the FPGA and whatever old chip you're trying to talk to. It's really unfortunate that so few modern digital parts are 5V tolerant. It isn't particularly hard to get around that limitation but it's one more obstacle.

Share this post


Link to post
Share on other sites

I'm actually about to do this exact sort of thing shortly (not with a SID, different sound chip). If there is interest I can start a new forum topic and rant about it as I go along complete with pictures.

  • Like 1

Share this post


Link to post
Share on other sites

I scraped ebay for some time ago and ended up with these 6581, SMC0608S, YM2203C, SAA1099P, SN76477N, AY-3-8910, but not that chip,damn..

Got also some dacs:TDA1543, DIR9001, BB PCM61P, MCP4921, YM3016-D, YM3014B, YM3012

 

Are these types of chips difficult to wire up?, going to read that thread anyway, looks very detailed, kudos to that!

Share this post


Link to post
Share on other sites

Your best bet is to look up the datasheets for each of those chips. Most of these sound chips have similar interfaces regardless of how they function internally. Usually there is a clock signal and then a parallel bus is used to access a series of registers within the chip. The number and function of these registers is specific to each chip but the difficulty is similar. The hard part will be coaxing them into making sounds that are pleasant to listen to.

 

For example, here's a datasheet for the AY-3-8910

http://pdf1.alldatasheet.com/datasheet-pdf/view/166797/ETC1/AY-3-8910.html

 

The other thing I would do is scour the internet for other projects incorporating the chips you are interested in using. There are quite a few chiptune synth projects out there.

 

The DACs are probably not terribly interesting. You can get pretty much the same result with a resistor ladder or a delta-sigma DAC in the FPGA.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now