Latest posts of: mace

Wow, I completely forgot about it in the meantime, but that is excellent work!

Quote from: robertmo on November 29, 2009, 07:57:13 PM

Are there any Game Blaster back pictures to check whether it uses IRQ or DMA? Or does anyone already know it?

I believe there are even entire schematics floating around.

Yes, sorry I haven't replied yet, I'll try to find it for you.

I can no longer find the schema I drew up myself.
But it's basically this one:

Only the 74 chip I used is a 74HCT04, in stead of the 74HCT00.
The 04 is an inverter, but the principle is the same.
If you have trouble figuring out the pin numbers with a *04 let me know, I can help you with that.

The power supply was a PC power supply as mentioned before.

Quote from: Doctor Creep on August 25, 2009, 12:00:37 PM

A friend got the same problem using Linux OS + MT-32 + USB-Midi cable. Can anybody recommend a sysex send tool for Linux?

Uh, cat ?

Quote from: Lennart on August 06, 2009, 12:58:33 PM

Quote from: mace on July 31, 2009, 06:50:14 PM

My guess is address decoding, I really need to get my hands on one so I can try to create a truth table and burn a replacement with it.

Well, if you promise you'll be careful with it and not fry it (or blend, grill, impale or whatever Wink

), I'm willing to lend you my Creative Music System card, so that you can study it. I live in the Netherlands too, so that's a nice coincidence.

Just PM me and we'll work it out.

Thanks!

I'm quite busy at work right now but in a few weeks things will quiet down some more and I'll be sure to take you up on your offer by then.

Yeah, those little differences make Roland, well, Roland. Cheesy

Quote from: Great Hierophant on August 01, 2009, 04:41:09 PM

Here is a high resolution scan of a Game Blaster:

http://www.crossfire-designs.de/index.php?lang=en&what=showimage&name=images/articles/soundcards/gameblaster.jpg&title=The Game Blaster&num=3

As can be seen, other than the CMS-301 chips, the rest of the chips with the exception of the CT-1302 chip are bog-standard 74LS series parts. If you only used those chips, would you be able to recreate the addressing scheme of the Game Blaster, I/O 210, 220, 230, 240, 250 or 260?

Good idea, you'd need the circuit diagram tho.

Quote from: NewRisingSUn on August 01, 2009, 05:48:33 AM

Remember that the Creative Music System/Game Blaster is basically a cut-down version of the Cubic CT/XT's computer's audio I/O card. I would assume that the chip handled speech in the original design.

The chip is a very basic PAL16, it cannot handle speech.

A PAL16 can be programmed with basic digital gates. Much like our modern CLPD and FPGA chips but again much more basic.

Quote from: Great Hierophant on August 01, 2009, 12:51:55 PM

Would the glue ICs on the card itself be sufficient to support the address decoding options the card requires? The Sound Blaster does not have anything similar on it and it supports CMS and alot more.

Quite possible, the glue chips are probably custom IC's or some kind of programmable IC, so they could easily handle it.

Quote from: robertmo on July 29, 2009, 08:44:33 PM

We will be able to check it in dosbox debugger when it supports these games.

And Harekiet also wonders what is that lage chip for

Maybe there are programming guides somewhere for game blaster so it will be possible to fingure out what is it used for.

My guess is address decoding, I really need to get my hands on one so I can try to create a truth table and burn a replacement with it.

Quote from: enigma on July 26, 2009, 12:12:48 AM

Sorry for digging out this old thread, but

I got the NCR rebuild of the DB60XG, which is 100% identical as far as I know.
I can't get the MT32 switching running there. It seems to have no effect.
I tried
gsplay.exe MT32
which worked for SCB-55 and I also tried running the MT32emul.mid

There seems to be no difference between normal GM set DB60XG and MT32 set DB60XG.
There was some difference between DB60XG and DB50XG except the Line-In capability.
Could it be that they left the MT32 compatible soundbank out for the DB60XG ?!?

Someone knows?

I dunno.

I can try it out though, I've got a NEC DB60XG too.

Quote from: Salient on June 09, 2009, 06:41:43 PM

Awesome!

I like the switch in the front, too.
Is it so, when you switch off the unit, the transformer keeps 'powered on'?
In my case it is like that, I was thinking of a true 230V on/off switch as well but then again, as far as I know a transformer with no load doesn't get hot and doesn't consume much power anyway.

No mine switches the 230 so no power whatsoever is drawn when it's off.

Edit: I still keep saying 220, haha. Grin

Pictures:

Overview:

Not my best soldering, I had to adjust the components a few times so it's kinda messy, works fine tho.

This is the swich on the front panel, I may change it for a less conspicuous one.

Here you can see the regulator I used.

Components used:

-IEC type connector with fuse holder as power input.
-SPST toggle switch
-transformer, 2x9V I forgot the current rating. Wired in parallel.
-LM2940T-9.0 LDO regulator, this is like a 7809 but with just 0,5 voltage drop.
-6800uF electrolytic.
-100uF electrolytic.
-2x 100n ceramic capacitors for decoupling.
-4x 1N5819 diodes for the diode bridge.

I've finally recieved my 9V LDO regulator, I'll install it tonight and post some pictures when I get the time to do so.

Quote from: Great Hierophant on May 23, 2009, 11:48:10 PM

Quote from: mace on May 23, 2009, 06:33:24 PM

Exactly right, and I can't stress that enough, Tip is negative, ring/sleeve is positive!!
This goes against the general standard.

Center negative AC adapters are more common with Japanese electronics. Nintendo and Sega used them in systems with external power bricks.

Really? I didn't know that.

Quote from: Salient on May 24, 2009, 05:05:53 AM

Oh, I installed the regulator just to be sure, I was in the assumption the 9V was used for some circuits and that the 7805 was there for specific parts only.
But as I now understand is that the whole system is just running at 5V?

That's what Laust said, yeah, I never realized this.

I'm going to check it today if I find the time, just to be sure.

Quote from: Laust on May 23, 2009, 08:54:30 PM

12V isn't harmful, the MT-32 will just run a bit hotter. The 9V input is routed straight to another voltage regulator, an 7805. These have a wide input range, all the way to 35V. However, the capacitors on the input are only rated 16V, so I wouldn't go beyond that...

Keep in mind that this only applies to the old-style MT-32 (not sure about the new one). I know that the CM-xx does "more" with the 9V input than route it to an 7805, so those units could be damaged by trying this.

Hmm, you know, I didn't even check that, but if that is the case then I can just remove the 7809 altogether, because regulating it twice is just retarded of course.

Salient, you've inspired me to do the same thing to my MT-32, Only I went and made a front panel switch.
My front panel was pretty scratched up in that place anyway so I didn't really mind.

Now all I had was a 9V AC transformer, and after rectifying and smoothing it leaves 10,5 volts DC. Which is not enough for the 7809 I'm using so it's outputting 8,5 volts. The MT-32 works flawlessly tho.

Now, I've ordered a LM2940T-9.0 which is a Low-dropout replacement for my 7809, the LM only has a .5 drop so the 10,5 volts should be more than enough to make a stable 9V.

My SC 155 has significantly less space inside, but I have a very small switching 15 volt supply which I will try to convert to 9V or I'll just put a 7809 behind it.

I have both a ACB-220 and a ACI-220-J

The ACB came with my MT-32 and is 9V 1200mA
The ACI came with my SC-155 and is 9V 1000mA

Basically anything 9V 800mA or more is going to be fine.

Quote from: Great Hierophant on May 23, 2009, 02:23:18 PM

The original Roland adapter is the ACB series. This adapter comes in 100, 120, 220 and 240 VAC varieties. The output is 9VDC, 1200mA. It is almost a universal adapter, it can be used with many, many other Roland modules and products. The MT-32 only requires 650mA, having a power supply with greater amperage than the device requires is never an issue because the device will use only what it needs. Make sure the tip of your adapter is center negative.

Exactly right, and I can't stress that enough, Tip is negative, ring/sleeve is positive!!
This goes against the general standard.

Quote from: Salient on May 23, 2009, 07:36:29 AM

Quote from: mace on May 23, 2009, 06:56:09 AM

That means that the lower one is swinging like a latin dance party. Cheesy

Well, isn't the whole point of these things to output music? Cheesy

Good point. Grin

Quote

I'm gonna get those caps and add them just to be safe. I never conciously realized it would be this 'bad'.

Quote from: Salient on May 23, 2009, 05:15:37 AM

I know those caps aren't there, I went for the quickest and simplest solution (and I didn't have them at that time).

The MT-32 is running for a year now without flaws but maybe i should still add them since it wouldn't be that much work.
Is the elco on the output REALLY needed?

Not necessarily the elco, but the 2 small ceramics really are needed.

Here's a picture of a oscilloscope and you can see what happens if a 78XX starts to oscillate due to poor decoupling (like in your case Wink

)

The top one has the caps installed, and the bottom one doesn't.
They look similar, but if you look in the lower left you can see that the scale of the top one is 20mV and the lower one is 2 Volts.

That means that the lower one is swinging like a latin dance party. Cheesy

After adding like 10c worth of caps the output oscillation is reduced by a factor of one hundred

Now it's perfectly possible you will never have any problems, but as you can see, you're walking a fine line here and you might just end up with a busted synth.