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livinginthestoneage
January 29th, 2007, 10:20 AM
Okay...Well, I'm going over some options for my planned project, and I need a sound chip...So far, I've come up with two, (although, feel free to suggest something else, if you have a better idea)

Well, I am wondering about an SID, or Paula...

And no, not the 8580 SID...I mean the "flawed" 6581 SID.

I know that Paula is part of a custom chipset for the Amiga, and I'm not sure if I can use the chip independantly from Denise and Agnus. I have no desire to use the other two, I'm not trying to re-invent the Amiga. ;) I also have no use for the additional (non-audio) portions of Paula, so meh...

Or there is the 6581 SID, or perhaps dual 6581 SIDs...

Anyone have any input on this?

Micom 2000
January 29th, 2007, 10:58 PM
Well I opened up one of my Amiga 1000s and couldn't see any chips labelled Sid, Agnes, or Paula, nor any flawed chips which might be the physically challenged Sid you mention. I didn't bother checking out my Amiga 2K or 3K since I doubted they would have people-named chips in them either. I do somewhat remember that there was Carlos or Pancho memory or something like that which I never could quite fathom.

Mind you I'm really a Tramiel ST kind of guy. No frivolity with Sam. Is it true he gave Amiga back to Commodore when he heard that the Amiga engineers were naming chips after thier girl(and boy)/friends ? Just an Amiga moment I guess.

The closest I've come across terminology like that was in the IBM PS2s where they had Lagunas and Bermuda motherboards (or something like that). And wasn't Lisa actually the name of St. Jobs daughter ?

Can you imagine her dismay when she had to intone at Apple birthday parties :

" I AM THE DAUGHTER OF JOB ".

And then a flash of lightning would illuminate her !!! FLASHHHH

An Apple moment I guess.

Who says nerds are dull and unimaginative ??

L.

carlsson
January 30th, 2007, 12:22 AM
The chips have code names, but not neccessarily printed onto the chips themselves. SID is the sound chip in Commodore 64 et.al. (UltiMAX, C128, B128, P500 and a few more). Paula is part of the Amiga chipset. I believe the "flaw" refers to how the filters were implemented in the different versions of the SID chip. Some musicians rely on the older implementation where sound differs from unit to unit, some prefer the newer, more uniform one.

I'm not good in hardware, but doesn't Paula work entirely with DMA samples while an old school chip like SID, AY, POKEY and so on generate sound from fixed waveforms? Of course, for most chips except SID the amount of waveforms is restricted to two: square wave and white noise.

Exactly what are you planning to do? While loose SID chips are a bit pricey in some places (if you have the right connections, they can be almost free, but let's assume eBay pricing), I'm not sure if Paula's can be had at all if you're not cannibalizing partly broken Amigas. Of course, sometimes it is cheaper to buy a partly broken C64 incl. shipping than just the SID chip.

livinginthestoneage
January 30th, 2007, 03:32 PM
Pokey is not happening...Pokey sounds awfully out of tune.

Anyways, I'm planning on designing a 16-bit computer from scratch, and teaching myself whatever I need to learn along the way to make it work. In the end, I'm planning on this thing being used as a synthesizer. I plan on obtaining the parts from broken computers (like a broken Amiga or C64, or a few, as I'm toying with the idea of multiple SID chips, if I do go the SID route, which I think I'm starting to learn towards.) I was wondering about the AY chip, but from the sounds of it, I'd be better off with a SID.

Now I'm trying to decide what to use as a main processor... Right now, I have a TMS9900L, or i could throw out 16-bit and go with a 6502 I have. I'm also wondering about using a 68000, or a 65816...I'm not using an Intel chip...I know that...I have a TMS9918A I'm planning on (so far) for using for the VDP, although something with a sharper resolution akin to say, the monochrome hi-res mode of the ST, would be better. Colors aren't a priority, and as far as I'm aware, the TMS9918A cannot display 80 columns.

Micom 2000
January 31st, 2007, 03:17 PM
Carlsson, that was meant to be an ironic, humorous take on the insider pretentions of some of us nerds. Especially when one hasn't a clue of what we are talking about. I should have possibly put a bunch of smileys in there, since nonsensical blatherings can be taken seriously. The english language, especially from Irish speakers must be taken with multiple grains of salt.

Since my father was Irish and my mother was Danish, dinner-times with my Danish aunt could be hillarious with my father presenting outrageous ideas and my outraged aunt refuting them, with my mother interjecting, "Hugh, Stop That ! , to his delighted grins and us kids hillarity.

Lawrence

carlsson
January 31st, 2007, 11:08 PM
Well, it wouldn't be a total surprise if some custom chips had code names printed onto them. In the case of the Amiga, I thought they did, because the code names are printed on the schematics supplied with the manual. I suppose the numerical codes appear on the schematics too, so one can locate which chip is which.

Heh, a homebrewn computer with a 68000, a 6581 SID and a TMS9918 sounds like an odd beast never heard of before. Are all chips reasonably easy to interface as long as you have the proper electronics skills?

livinginthestoneage
February 2nd, 2007, 02:50 PM
I'm not entirely sure if they are easy to interface, to be honest. I have some electronics skills, but this project is more so to teach myself the skills I don't know.

I'm not sure if it will be a 68000 yet, it may possibly end up being a 65816, as I found one. Also, in addition to a 6581 SID (or a pair, as I'm thinking the SID sound in true stereo would be great), I've also come across an EMU8000 chip that I'd like to add as well.

In the end (probably a few years from now), I plan on this computer being mostly used just to generate music, which explains why I may settle for a TMS9918A (although, I'd prefer something that is capable of 80-columns, I don't think the TMS9918A can support that).

I did find a MC68EC000, but as I'm probably going to start with breadboards, i'm thinking I should stick to chips that are DIP.

Does anyone know of a homebrew computer forum anywhere? I tried to find one, but this was the best I found.

80sFreak
February 2nd, 2007, 03:35 PM
6502.org (http://www.6502.org/) is a great place to start. Also, it might be a better idea to start with something from that site to learn how everything goes together and see how it works before creating your own design..

Just my two copper pieces...

Cheers,

80sFreak

livinginthestoneage
February 3rd, 2007, 02:18 AM
Heh...well lucky me. I just got two DEC/Harris J-11 processors. I believe these things support SMP as well...

Kaptain Skitzo
February 3rd, 2007, 07:04 AM
I happen to have some loose Amiga and C= 8-bit chips. If you are interested, feel free to drop me a line.

carlsson
February 3rd, 2007, 11:03 AM
Perhaps a MC6845 (or MOS6545) is a suitable low-end graphics chip for 80 column output?

livinginthestoneage
February 3rd, 2007, 03:52 PM
I looked into that, and it seems like it will do the job. These J-11s I just don't think will cut it. It would be simpler and have a better result to just go with a 65816 clocked at 22MHz, which I'm thinking is what I'm going to do.