Re: Universal Sound Board?

At 12:31 PM 5/2/97 -0800, you wrote:
>>I agree. When you want a DAC, buy a DAC. Though I think you can do
>>multiplies quite a bit faster in a PIC than the 8051 (I've written math
>>packages for both). So if you want to do any kind of, on the fly, volume
>>control, sending the data through a PIC might get you a little better
>>thorough put...
>
>Hmmmm. We could do what the Universal Sound Board does and use PWM outputs
>from the PIC tied to caps to make a envelope control for each voice
>output...
>
>Doesn't the 8051 have a MUL instruction? Thought for sure it did. Seems
>like its a 24 clock execution time? (So yeah, if you run a PIC at 20MHz
>and the 8051 at 12MHz, you'd have what-- around 48 instructions on the PIC
>to do a multiply and come out ahead of the '51... That shouldn't be too
>tough. ;-)

It must. The company I worked at two jobs ago (I contract) was a medical
manufactoring company. My job was to program an 8051 derivative, that was
connected to a DAC, to make all the sounds needed by a respirator. (Kind of
a Respirator Universal Sound Board) I had to do all the attack and decay
envelopes in software, and I didn't write MUL routine, so I'd say yes, it
does have a multiply. (As a side note: On one version of the sound card,
when something *bad* happened, oh like breath delivery going "flatline" the
error sound that sounded was Bullwinkle saying "Now watch me pull a rabbit
out of my hat!". Pretty funny, but the FDA takes such things VERY
seriously, and I personally erased that copy of the EPROM, just to be sure
it didn't go any further. Never can tell you know. And I can't imagine
anything more uncomfortable than being questioned in a wrongful death suit,
and having the defense attorney playing that sound. *Shudder*)

>>I should start by saying Tempest *is* my favorite game, but none the less, I
>>think the sounds of those Pokey chips basically *suck*.
>
>Well, in practice I'd agree with you, but I think the old "beep-boop" and
>weird grinding periodic noise sounds the POKEYs make are kinda cool in that
>"retro" way. And 4 voices for $.80 (price of a Ball-Blazer cart) is hard
>to beat...

Oh don't get me wrong, I wouldn't change the sound of my Tempest! I just
think they used what they had (what was cheap) and ended up with lousy white
noise, and tinny, little "beepie" sounds. And I know you couldn't make the
analog sounds that were used in even the original Asteroids. (Damn! I can't
believe I paid $2 for some old carts to get the Pokeys, I don't even know
what the carts are.)

>>>Or if you're going to use serial anyway, just use a single PIC and one of
>>>those Max528's. About $7 with serial input and 8 voltage output 8 bit
>>>D/A's in one package...
>>
>>I like this idea a lot! I'll have to look into that Maxim(sp?) chip (Does
>>Maxim make some cool chips or what?). I imagine the clock rate needed to
>>constantly refresh 8 continuous samples of audio is pretty high. (Oh like:
>>8*8*SampleRate)
>
>I think it's more like 16*8*rate since there's going to be some bits to
>select which channel to talk to. I think it's a 3-wire interface.

Ouch. That's fast.

>>It's also pretty simple to use an external latch (or two) as part of the
>>addressing of the 68HC11 to allow for banking. And the 68HC11 being a nice,
>>straight forward, Von Neuman device, table look ups [of the sampled wave in
>>EPROM] is simple. Though for simpling data moving, it is a tad slower than
>>tbe PICs...
>
>Yeah, I always just OR the program and data store enable pins together on
>the 8051... Aside from still having a "DPTR" it's a little more "normal"
>to use that way... ;-)
>
>>I know, hence the external counters and a lower end PIC. But then again how
>>many sound cards do you intend to buy? Even if you used 4 $11 PICs, another
>>$50 worth of "other stuff", a $50 PCB. Considering the prices I've paid for
>>my collection of Sega Boards, a "Universal Sound card at $150" sounds like a
>>deal to me! If one were available "right now", I'd be filling out a check,
>>"right now"! And hell, if I owned the card I'd want the $25 reprogrammable
>>PICs anyways! I'd want a "Universal" Universal Sound card!
>>
>>Am I the only one to pay more than $150 for a game board?
>
>Well, there's those "magic" marketing price points.
>
>(some lower ones) $99, $199, $249, $499, $999 (and the higher ones)
>
>The rationale being that a particular group of consumers will be willing to
>purchase a particular item since it's "under" a price that they consider
>"high".
>
>I'm probably overly price-aware since our "real" business is low-margin,
>high volume. If we sell 250,000 or something a month and we're paying an
>extra $.10 for it that's $300,000 a year off the bottom line. I definately
>want the multi-game ROM/input mapper board to be $99 or under. If the
>UniversalSB doesn't fit on there at that price I suppose it could be
>another $99 board... ;-)

My current job is consumer products and I can get caught up in the same
thing (save a dime and your a hero). So I was just taking a step back and
wondering how much *I* would pay, once.

I think the real key here is that if your volunteering to lay this out by
(*choke*) hand (*cough*), a low part count would be the goal. One $100 part
that did everything we needed, with just the data and address lines needing
connecting would be much more desirable than $20 worth of glue logic that
did the same thing, if it consisted of 39 ICs, 10 transistors, 14 caps, etc.

<snip>

>
>Maybe we should be looking at modifying the existing Universal Sound Board?
>It already has 9 DACs with Whit noise generators, etc. We could bank
>switch the downloadable RAMs out with EPROM and add another couple
>interface port latches and use the existing hardware card with a new
>program to be the sound source for Zektor/Elim/SF...

Sounds like a more *realistic* goal, if you could create all the proper sounds!

-Zonn
Received on Fri May 2 14:15:49 1997