ZX81 driving a SID 6581

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crankorgan
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ZX81 driving a SID 6581

Post by crankorgan »

After the BBUM project I started collecting parts. I got two SID chips out of broken 64 computers. I won an auction for a bigger proto board with built in supplies. Now I got the SID mounted in the new proto board along with a LM386 audio chip.
The audio chip is working but the SID is giving me heartaches. I got a 1mhz osc feeding the SID and all pins have their requirements. The addresses are tied to ground so any DATA into the data inputs should make sound. Right now I just have jumpers on the SID chip. I emailed a guy asking for a sequence to hit the data lines with. Maybe one of you guys knows. The Internet seems to have big gaps on SIDs. Most chips have a diagram that shows how to test the chip using jumpers. I think the SID needs to be hit with a sequence to get it to make sound. I am reading about a TEST input? Anyway that's what I am up too!
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Andy Rea
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Re: ZX81 driving a SID 6581

Post by Andy Rea »

i found this http://www.waitingforfriday.com/index.p ... _Datasheet

not much help on this i'm afffraid, but i'd be guessing your gonna need a bunch of logic, since as the sid runs at just 1Mhz, and the data transfers need to sync up with the clock signal supplied to the sid... i reckon maybe you could divide the 3.25Mhz clock of the zeddy by 3, giving just over 1Mhz, and then your gonna need some trick logic to insert wait states (probably) to make sure that the Z80 writes to the SID happen at the right time...

Ummm good luck

Andy
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crankorgan
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Re: ZX81 driving a SID 6581

Post by crankorgan »

I found a guy that is driving one off a parallel port.

http://www.loper-os.org/vintage/paralle ... rasid.html

There always seems to be a trick! I got that data sheet. I found this guys info!

http://www.mikekohn.net/micro/sid_player.php

I think the CS signal is the Key!
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1024MAK
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Re: ZX81 driving a SID 6581

Post by 1024MAK »

SID chips have been interfaced to non-Commodore computers, e.g. there is a design in the UK for an Acorn BBC Micro to interface to a SID. See http://stardot.org.uk/forums/viewtopic.php?f=3&t=2530

If I were to have a go at getting a Z80 based computer to talk to a SID, I would try using two register / latch chips (74HC373). One to drive the address and some of the control lines and the other to drive the data bus lines. You would need a flip-flop type "one shot" circuit to enable the latch chip outputs only when they both have "new" data, and the 1MHz clock is high, and of course for one data transfer only...

Good luck :mrgreen:

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crankorgan
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Re: ZX81 driving a SID 6581

Post by crankorgan »

1024Mak

Yes I am going to use the three 74LS373 LATCHes wired on the first proto board that drove my Christmas light project. Latch 1 will do address and latch two will do Data. It looks like three will have to do the /CS as a strobe. I was hoping just and address and data would do the trick. I can also use latch three to do RESET. From what I read /CS is more of a strobe input than Chip Select. Thanks for the link.

John
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Andy Rea
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Re: ZX81 driving a SID 6581

Post by Andy Rea »

Sounds good to me, driving everythin off port/memory decoded latches would certainly make it all slow enough to be reliable read by the 1Mhz clock of the SID.

Andy
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sirmorris
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Re: ZX81 driving a SID 6581

Post by sirmorris »

SIDs need note on/note off triggers in order to make sound, you can't just poke random data at them. There's a test program you could convert here:

http://ploguechipsounds.blogspot.com/20 ... hmark.html

When I made AtomSID I didn't worry about syncing with any clocks...

C
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Andy Rea
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Re: ZX81 driving a SID 6581

Post by Andy Rea »

sirmorris wrote:
When I made AtomSID I didn't worry about syncing with any clocks...

C
yeah but teh acorn CPU runs at 1Mhz does it not ?, according to that datasheet the SID clock is used to latch the data into the registers, so i was just guessing that maybe a Z80 running at 3.25Mhz, might be a tad too quick to write directly without waits, but that all bye the bye now if the SID is going to be connected via latches, which will take many cycles to write new data to, and will surely be slow enough :D

Andy
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crankorgan
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Re: ZX81 driving a SID 6581

Post by crankorgan »

I love this stuff to a certain point. I got the SID on one proto board with all it's requirements met with jumpers but no sound. Today after a long walk I will add two push button switchs. One so I can do a RESET and one that hooks to /CS. With the Addresses wired to 00000 and Data wired I should get a sound after it is powered up and RESET is hit followed by /CS.
I am old school! I have to know what a chip needs to function before I wire it.
crankorgan
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Re: ZX81 driving a SID 6581

Post by crankorgan »

The RESET and /CS switch did nothing! Off to do more reading!
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