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SubjectRe: Sounds suspiciously like a homework question :) *nt* Reply to this message
Posted bysellenoff
Posted on08/10/04 12:22 PM

Thanks for nothing Bart T!

It's not a homework question, unless you think someone who's 32 years old still has homework to do! Maybe I need to post a copy of my driver's license and passport to get a question answered!?

It's quite a sorry situation when that's the first and only response to someone asking for help! I've seen it before in forums all over, and sometimes it is obvious that a student is trolling to get free homework done, but I still think people should be given the benefit of the doubt.

Sorry if I sound pissed, but I am quite insulted by your response. I only wish I *did* get an education in any of this stuff when I was in school, then I wouldn't need to be asking for help.

FWIW - I'm not a newbie to emulation, digital circuits, or hardware.. (see www.pinmame.com for the majority of my work, plus some drivers for mame & fixing up a cpu core for mess(tms7000)) but the problem is it was all *self taught* in my limited spare time, and as such, there are glaring gaps in my understanding of certain things.

The question comes from sound board hardware for an Alvin G & Co. pinball machine which I am trying to improve the existing emulation I did. The current music plays too slowly, yet the samples play too fast. I've mucked around with guessing a combination of CPU Freq & FIRQ rate, and can't seem to get something quite right..

Having recently gotten access to a manual, I thought I'd try and figure it out from the schems. So I grabbed hold of the 6809 datasheet and did some reading, but I just don't understand the very brief explanation. That's where the question comes from...

I would very much appreciate some kind of help!

> > Was wondering if someone could help me understand how to calculate the timing
> of
> > these 2 signals from the 6809.
> >
> > Assuming the external crystal is set to drive the 6809 @ 8Mhz (which i believe
> > is the top speed the chip can go - on the 68B09), what would the frequency of
> > the E & Q lines be?
> >
> > The hardware i'm looking at uses E to pulse a 4020 counter which eventually
> > toggles the FIRQ of the 6809, and obviously I'm trying to calculate the
> correct
> > freq. to generate the firq.
> >
> > I've looked over the 6809 datasheet and just don't really follow it. I've
> never
> > been good with timing in general, and those datasheets are not written to be
> > easily understandable unless you already get the concept! :)
> >
> > So if someone could explain, not only the answer, but how I could have derived
> > the answer from looking at the datasheet, it would be greatly appreciated..
> >
> > Thanks
> > -Steve
> >
> ----
> Bart

Entire Thread
Subject  Posted byPosted On
*E & Q timing on M6809  sellenoff08/09/04 06:15 PM
.*Sounds suspiciously like a homework question :) *nt*  Bart T.08/09/04 11:55 PM
...Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 12:22 PM
...*Re: Sounds suspiciously like a homework question :) *nt*  Bart T.08/10/04 09:12 PM
....*Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 11:56 PM
...*Re: Sounds suspiciously like a homework question :) *nt*  Riff08/10/04 08:21 PM
....*Re: Sounds suspiciously like a homework question :) *nt*  sellenoff08/10/04 11:53 PM