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There is a lot of circuitry connected to the piezo. I'll trace it out.

OK, it's an oscillator that R15 enables. It's got the same wiring as this: http://rayshobby.net/learning-electronics-1-multivibrator/

C1 and C2 are 0.003uF, R1 and R4 are 1K, R2 and R3 are 100K.

Instead of a battery, the common resistor leads are connected to the TMS's R15 output and one side of the piezo. The other side of the piezo is connected to T1's collector.

I connected a resistor between pin 5 of the TMS socket on the PCB and VSS, and measured a 2.4kHz signal at the piezo.

And that works out well with the equation on that web site, which gives 2.405kHz.

Entex Jackpot Blackjack/Gin Rummy has the same circuit, but the components are laid out a lot easier to trace! Pretty much exactly like that schematic was drawn.

Last edited by seanriddle; 04/23/15 10:37 PM.
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Got it, thanks. =)

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sean do you have the top-metal die pics of the Coleco h2h games?


Originally Posted By kevtris
Another one bites the dust!

http://blog.kevtris.org/blogfiles/Handhelds/Mattel%20World%20Champ%20Baseball/

This one had a really weird VFD in it, with strangely laid out grids, which are marked up on the ident image.

Added and working.

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Originally Posted By hap
sean do you have the top-metal die pics of the Coleco h2h games?

I took pics but didn't composite them. I'll stitch them together and post them.

Edit: I posted the H2H Football die with the other info. I'll let you know when Baseball is out there.

Last edited by seanriddle; 04/24/15 08:56 PM.
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Originally Posted By hap
Entex Raise The Devil and Electronic Poker are working.

Is there anything non-standard about the speaker setup in the poker game? If so, can you make a schematic? In MESS, I'm getting messy farts instead of beeps.


Nobody likes messy farts. ewww. I traced out the audio circuit for donkey kong. Looks like pin 53 is the audio itself and pin 35 is the "decay" pin.

There's one transistor that just turns the feeper on and off (via pin 53) and the other controls the pulldown resistor on the feeper which controls its volume. There is a 0.47uf cap and 91K resistor on the base of it, which is connected to pin 35.

This is similar to how le boom does it volume decay.

Galaxian's audio works like you said- pin 40 is the audio output, and pin 41 is the oscillator control. There's a resistor/cap circuit on pin 41 so that it can be controlled.

Looks like when 41 is low, it discharges the capacitor and stops the oscillator. When high, it will oscillate at maximum frequency, and when tristated (input mode) it will slowly decrease in pitch. I was thinking of throwing it on a scope to see what happens.

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Originally Posted By hap
kevtris is it possible to determine the number of stack levels in HD388x0 by altering your dumping program? For example, call from address A 1 time, then from address B xx times, and return xx+1 times to see whether or not address A is lost.

The reason is, CGL Super Kong works ok if I increase the stack size in the mcu emu core. This game has the B revision of the MCU. Hitachi docs say the stack size is 4, maybe they increased it on the B rev.


Hmm, not really. I am using the factory test code now to dump these. I wouldn't doubt it however if they increased stack levels and maybe did other things- they did reset the mask numbers. I wouldn't have expected them to do this unless they changed functionality somehow too.

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I posted the Head to Head Baseball top metal die shot.

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I tried to dump the NEC 8048C that was inside that game... unfortunately I got absolutely nothing out of it. I haven't encountered a "protected" one before; I'm pretty sure I have dumped similar NEC 8048's so I dunno what's going on. I'll have to fire up the allpro and give it a shot on there, since I have an 8048 dumping script for it.

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Thanks! I'll start on the h2h football game. Are all those early American football games so complex because they're trying to milk off Mattel Football success and imitate the concept?

Mattel Championship Baseball (the game kevtris dumped) is also very complex. The ones by Entex and Bandai are gambling minigames compared to it.

kevtris: 8048 is from what? The Mego Mini Vid game? As for Galaxian audio, there must be more to it than just decreasing frequency. If my ears are right, I hear a change in duty cycle time too. https://www.youtube.com/watch?v=z4XndQf6NnU

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the 8048 is from that mini vid sea battle game. On Galaxian, what happens is it's a relaxation oscillator I think, so as pitch decreases, I guess the effective duty cycle would change too. The pulse width doesn't change, but the period between pulses does. i.e. the high time is constant but the low time varies.

And yes, that baseball game is stupidly complicated. The football game I dumped by mattel is also stupidly complicated as well (world champ. football).


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