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Digiblaster

Started by mr_lou, 08:09, 24 May 10

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Do you have a Digiblaster expansion for your real CPC?

Yup, I made it myself!
10 (27%)
Yea, I bought it.
3 (8.1%)
No dude, but I'd like to have it!
19 (51.4%)
No way, not interested in anything but "real" CPC sound
5 (13.5%)

Total Members Voted: 36

mr_lou

I've gotten a bit curious about the Digiblaster expansion.
  So I looked at the schematics. It seems relative simple.
So I guess the only way of getting myself a Digiblaster, is to build it myself?
  How many here has a Digiblaster for your real CPC? Do you know of anyone I can pay to make it for me (because I'm lazy)?

EDIT: Adding link to schematics.
http://cpcwiki.eu/index.php/Digiblaster_howto

woody.cool

I voted " No dude, but I'd like to have it!"
I've not got ANY expansions for my CPCs except an Amstrad FD-1.There's so much that I want to get for the CPC too, but never see/hear of much expansion wise.

robcfg

I'm in the process of building one.


Let's see if I can do it right!  8)

mr_lou

woody.cool, I'm using a CPC464 too. I also only had the FD-1 external drive at first. But then I managed to build myself a 3.5" drive, and later bought a 64k expansion. So now I have a CPC464 with 128k, 2 disk-drives and tape station.  :) I prefer to stick with the 464 because it's the one I grew up with.

robcfg, I have the centronics plugs, so I only need to buy the components. But I never know how to assemble the components. I should probably buy one of those printboards that's full of holes, but I've never really gotten the grasp of electronics, even though I've been very interested.

We ought to have an electronics-dude here at the forum, that we can pay for doing projects like this for us.  :)

For now I've written octoate asking him if he's interested in selling his old Digiblaster he made for his CPC464 long time ago. If he isn't interested in selling, and if you manage to make your own, then you should start a small production line for this thread.  8) hehe

woody.cool

Quote from: mr_lou on 11:19, 24 May 10
woody.cool, I'm using a CPC464 too. I also only had the FD-1 external drive at first. But then I managed to build myself a 3.5" drive, and later bought a 64k expansion. So now I have a CPC464 with 128k, 2 disk-drives and tape station.  :) I prefer to stick with the 464 because it's the one I grew up with.
I have a CPC6128 as well as a CPC464. I grew up with the CPC6128, but prefer the CPC464 because on the odd occasion that I use tapes, they are far more reliable in the internal tape deck of the CPC464 than an external player of a CPC464.

robcfg

 
QuoteI should probably buy one of those printboards that's full of holes


That's exactly what I've got  ;)

Devilmarkus

#6
I voted for "Yup, I made it myself!"

I built it in the 90s. Sad that I lost it :(

Digiblaster is really very simple to build.
Perhaps someone could improve it to get stereo sound?
(use 2 ports instead of 1?)
Could be done by exact port number.
Digiblaster uses the printer port which has range between EF00 and EFFF.
Perhaps this could be splitted?
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Bryce

I made my own. I made a PCB layout for Centronics Port, still have it somewhere I'm sure. I'll upload it if anyones interested in etching the boards.

Bryce.

MacDeath

Just a question concerning those additionnal Sound cards :

Do they add a channel ?
Does the jack output features the normal sound signal (the 3 AY channels) + the extra channel ? (mixed) or do you have to pass through and Hi-Fi mixer ?

I know the speech synthe are some thing like that, but more as some kind of programmable pseudo MIDI stuff...
This one add 8bit samples so you have to put direct datas instead of instructions to a special vocal synthetizer.
Yet the advantage : it can pass through the printer port, so in fact you "print" the sample...

Is it better CPU-wise to use this ?

Another advantage is that you keep you extention port free for other stuff (better mass-repartition on the ass of your Amstrad...lol...).


mr_lou

Quote from: MacDeath on 18:21, 24 May 10
Do they add a channel ?
Does the jack output features the normal sound signal (the 3 AY channels) + the extra channel ? (mixed) or do you have to pass through and Hi-Fi mixer ?

As far as I understand, it only gives you an additional feature, of being able to playback sampled music, like MOD files on the Amiga.
The Digiblaster outputs only sampled music. AY-sounds still comes from the standard output plug, not from Digiblaster.
However, I think it would be relatively easy to connect the AY-output to the Digiblaster, so that you only have 1 general output for both sound types.

Quote from: MacDeath on 18:21, 24 May 10
Is it better CPU-wise to use this ?

As far as I understand, using Digiblaster (sampled music) is actually rather harsh on the CPU. Devilmarkus tells me it takes about 96% of the CPU. But I'm thinking, that doesn't matter if it's used for background music in a game-menu.

Quote from: MacDeath on 18:21, 24 May 10
Another advantage is that you keep you extention port free for other stuff (better mass-repartition on the ass of your Amstrad...lol...).

That's true! I thought so too.

fano

Playing samples is heavy for CPU.Do not dream , it is not possible to play a game and to play digiblaster (or samples) in the same time as they eat almost all CPU time.
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Bryce

You can't feed the normal AY sounds into a digiblaster. The digiblaster is nothing but an extremely simple digital to analogue converter. Send values to the printer port and it creates analogue levels according to the value sent. This is obviously more taxing on the CPU, because you literally "build" the values of the output curve with digital values. Definitely not something you can do in the background.

Bryce.

mr_lou

Well I didn't have the patience to wait for Octoates reply, so I've ordered the parts now.
Then time will tell if I manage to build the thing.

How's it going with you robcfg?  :)

Octoate

Quote from: mr_lou on 21:27, 24 May 10
Well I didn't have the patience to wait for Octoates reply, so I've ordered the parts now.
Then time will tell if I manage to build the thing.
Sorry, my mail queue is still growing and I am not the fastest one to answer, but I wouldn't sell it anyway. It's so simple to build and very cheap that it won't make any sense to sell it.
--

mr_lou

#14
Quote from: Octoate on 23:37, 24 May 10
Sorry, my mail queue is still growing and I am not the fastest one to answer, but I wouldn't sell it anyway. It's so simple to build and very cheap that it won't make any sense to sell it.

Surely that would depend on what I'd be willing to pay?  ;)
Anyway, I'm not complaining about your response time. I'm merely acknowledging my own impatience.  :)

It might be simple to build for some, but I'm sure that for others it's a complex task. From finding the parts, to assembling them. Otherwise we'd all have one.  8)

And we should all have one, shouldn't we? The poll seems to indicate so at least.


Anyway, I have a question about Digiblaster playback. When I listen to MDL files using standard AY output, I've noticed that volume commands from the MOD are ignored. Are they also ignored when using Digiblaster output? Is this a general limitation with sampled sound on the CPC, or only when using AY output?



EDIT:
MacDeath: I've just seen the demo  Digital  Orgasm, which uses sampled music. And despite of this, lots of  things are going on on the screen. That's impressive I think. (Even  more so that it runs on my CPC464 (128k / CRTC2)).

arnoldemu

#15
The digiblaster sound output is seperate from the AY.

It is possible to play digiblaster at the same time as AY but to get best effect you would need to mix them externally to the CPC using extra hardware. They both have their own outputs.

Playing a digiblaster tune does take a lot of CPU power. It would not be possible to play digiblaster in a game.
A demo can do it because the play routine has been patched and the effects have been squeezed into the very little spare time.
The whole demo has been "cycle counted" so that everything runs and the music plays ok.

In a game you don't have that luxury because cycles change as things change on screen, and in addition because the digiblaster is not interrupt driven you can't play it interrupted and must use the cpu to time data sent to it.

However, having a sampled tune in a title screen or something similar is a good alternative, or pausing the game to play it.

Now this is where the kc compact is good, you can reprogram the interrupts and here, digiblaster could be played while a game is running.

EDIT: My digiblaster was given to me already constructed, but I also bought some parts to build my own.
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mr_lou

Quote from: arnoldemu on 09:45, 25 May 10
The digiblaster sound output is seperate from the AY.

It is possible to play digiblaster at the same time as AY but to get best effect you would need to mix them externally to the CPC using extra hardware. They both have their own outputs.

That's what I thought! So indeed that does mean that we can make a music-disk with 6-channel music.  :)
The player routines just have to be merged. E.g. the player routine for an MDL file + the player routine for a STarKos track.
First create a 3-channel MDL file using Digitracker, then a 3-channel SKS file using STarKos (or Arkos Tracker), and then play both tracks at the same time. Could be groovy.  8)
The Digiblaster just has to be built with an extra jack-input plug, so that you can connect the output of the AY into the input of the Digiblaster, so that the output of the Digiblaster contains both outputs.  :) Kinda like the sound from the Amiga 500 goes into the TV-modulator using a Y-cable.

Who can make a player-routine that takes care of playing an MDL and SKS file at the same time?

Quote from: arnoldemu on 09:45, 25 May 10
However, having a sampled tune in a title screen or something similar is a good alternative, or pausing the game to play it.

That's what I think yes. I vote that everyone gets a Digiblaster, and future games uses sampled music in the title screen more often.  :)

Quote from: arnoldemu on 09:45, 25 May 10
EDIT: My digiblaster was given to me already constructed, but I also bought some parts to build my own.

Those who has extra Digiblasters should sell 'em to one of the many who voted "No dude, but I'd like to have one".  ;)

Bryce

Ok, it seems that quite a few people chose the "No dude, but I'd like to have one", I'll see what it would cost to make a small batch of them (Centronics only though) and get back to you with a price. Who's REALLY interested, or did you all just click it, but not really want one?

Bryce.

mr_lou

Quote from: Bryce on 11:56, 25 May 10
Who's REALLY interested, or did you all just click it, but not really want one?

You can't ask a question like that.
You'll have to put up a price, and ask who's interested enough to pay that amount + shipment.
I've just ordered the parts, so I know that the parts alone is about at least 10 euro. It will probably take you at least 1 hour to built and test. How much is your time worth an hour?  ;)

I'm gonna try and see if I can built one myself, now that I've ordered the parts. I was thinking about trying to put it inside my CPC, since I never use the printerport for anything anyway. And then hook the output up to the existing jack output.  8)
Not sure if it's a good idea yet, but it sure sounds groovy, doesn't it? hehe

Bryce

How much is my time worth? You can't ask a question like that! :D If that was a factor, I wouldn't be able to supply them at any reasonable price. The price also depends on how many people want them. It's less time and effort to make a batch of say 10 parts, than it is to make them singly, so I would only make one batch. The component prices won't change much for such a small batch, so yes, I presume the parts would cost about 10€ per Digiblaster. But I can't offer 3 or 4 different types, the choice of Internal / external / English / German / Plus versions will have to be decided collectively. A plus version would probably make most sense, as you can connect it to a normal CPC with a printer cable. The english version is probably a no-go, because I doubt I can source those edge connectors any more. Or I could just offer the bare board (components but no connector) and let the user connected as he/she sees fit.

Bryce.

mr_lou

Luckily I managed to save a lot of those edge connectors from my girlfriend's fathers basement, before he cleaned it up and threw a lot of old hardware out. There was a bunch of those connectors from old PC floppy cables.  :)

Since my CPC's has those edge connectors, I'm not in your target group. But in my opinion, I think you should make a poll, asking how many is interested in buying one with centronics plug, and put an estimated price too.
I also think you should add an input plug from the AY-output, so that people don't have to switch plugs when switching between games/demos that uses AY-output / Digiblaster output.

A little question about that: Since the Digiblaster output is mono, it would probably render the AY-output mono as well, if we just connect the two outputs together, right? But can that be prevented by using 2 diodes to split the Digiblaster output into stereo before connecting with the AY-output?

I'm planning on either using a little stereo jack to stereo jack cable from AY-output to Digiblaster input, to mix the outputs, so that I don't have to switch between the AY-output and Digiblaster output manually all the time. Or else just solder everything together inside my CPC, to achieve the same effect, only more compact.  :)

Bryce

You'll probably have to make some sort of mixer arrangement, with "dual-mono" from the digiblaster being mixed with the AY output. Haven't checked exactly what the AY output signal looks like, but a few diodes might be enough.

Bryce.

mr_lou

Quote from: Bryce on 12:58, 25 May 10
You'll probably have to make some sort of mixer arrangement, with "dual-mono" from the digiblaster being mixed with the AY output. Haven't checked exactly what the AY output signal looks like, but a few diodes might be enough.

That's what I hope. But how to mix 2 signals otherwise? A small circuit needed?

Bryce

The proper way would be to use a pair of op-amps with some balancing and gain feedback resistors and a capacitor or two to filter out the DC, but that's getting too complicated. The easiest (cheap and nasty) way is to balance the signal with two resistors (in line with each input signal) or maybe use potentiometers so that you can balance the two inputs to the same volume level.

Bryce.

Or was that complete "spanish" ?

mr_lou

Hmm... well, I'm no electronics expert. I'm just enthusiastic.  ;)

Found this when googling. http://www.all-electric.com/schematic/simp_mix.gif

Don't you agree, that if you're about to make a batch of new Digiblasters, they should mix the AY-output into 1 general output? Wouldn't that make the Digiblaster more attractive in the future?

I might attempt to build-in such a mixer in my own Digiblaster somehow.

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