6802 clock

pin

(so

divide

why not? isn't the devider on chip?

I'm building a simple 6802 single board system. I want to drive the CPU with an external oscillator, rather than using a crystal (got lots of 4 pin oscillators, not so many crystals). When using a crystal, the frequency of the crystal gets divided down by 4 by an internal part of the processor (so you use a 4 MHz crystal for a 1MHz clock).

When using an external oscillator, like I want to do, does the same divide by 4 occur? That is, should I use a 4 MHz external oscillator, or a 1 MHz oscillator for a 1 MHz system clock?

Lee K. Gleason N5ZMR Control-G Consultants snipped-for-privacy@houston.rr.com

--- Motorola spun off their µC product line to Freescale Semiconductor, but I don't think you're going to find much 6802 around, since it's been obsolete for a while.

Freescale suggests Rochester Electronics as a possible source, and Google will give you lots of hits. If what you're doing is new, why do you want to use a 6802 anyway?

If you choose to reply, it's considered, in this group, to be courteous if you bottom post.

-- John Fields Professional Circuit Designer

Sometimes a good 8-bit 1 MHz processor is all you need.

By the way who makes the 6802, is Motorola still around?

When using an external oscillator, like I want to do, does the same divide by 4 occur? That is, should I use a 4 MHz external oscillator, or a 1 MHz oscillator for a 1 MHz system clock?

Lee K. Gleason N5ZMR Control-G Consultants snipped-for-privacy@houston.rr.com

You just 'top posted' btw !

Graham

John is absolutely right. For the effort it would take to track down data sheets and crap on that old of a part simply doesn't make any sense. I did a quick google on "6802 data sheet", without the quotes, and out of thousands of answers, none of them was about the old Moto micro. Heck, I saw a Basic Stamp Development Kit in Fry's not too long ago, for about a hundred and twenty-five bucks.

What country are you in?

Good Luck! Rich

--
Yes, but that\'s not the point, which is that the 6802 is obsolete and
only available from "surplus" dealers.

For a desperate one-off, that might be OK, but going through the
expense and hassle of stepping back in time when _many_ good 8 bit µC
are available for cheap in the present hardly makes the exercise seem
worth while.

On Sat, 23 Jul 2005 15:36:16 +0100, Pooh Bear wrote: ...

And, as usual, the middle ground gets lost in the noise of the battle.

It's not about "top posting" or "bottome posting". If you're responding to a certain item, snip all of the irrelevant crap, but put your answer underneath the question. What's so hard about that?

I used to be a top-poster, and I made all of the arguments in favor of top-posting, like, "But my comment is the most recent!" "But my comment is the most important!!!" that sort of thing.

Well, I've personally settled on, "When in Rome, do as the Romans do."

Although, in a multidimensional thread, intermediate posting can facilitate the discussion, but that's apparently WAY too advanced of a concept for the majority of people to grasp. Sigh.

Thanks! Rich

No I was just asking? Motorola came up with a good range of micro, I went to a few of there seminars, back in the 70's

--- Motorola spun off their µC product line to Freescale Semiconductor, but I don't think you're going to find much 6802 around, since it's been obsolete for a while.

Freescale suggests Rochester Electronics as a possible source, and Google will give you lots of hits. If what you're doing is new, why do you want to use a 6802 anyway?

If you choose to reply, it's considered, in this group, to be courteous if you bottom post.

-- John Fields Professional Circuit Designer

Then your news-client is broken. Cutting irrelevant parts does help, too.

--
Met vriendelijke groet,

   Maarten Bakker.

I beg to differ. Everything appears out of context.

That attitude is likely to cost you many a response. So you won't see some 'useful shit' since many ppl won't bother replying to an arrogant top-poster.

Do you not turn your head to listed to ppl too ? Maybe you only see and hear what you want to ?

Graham

p.s. note the way I responded individually to each item. You can't do that with top-posting.

Quite a few people build things using obsolete microcontrollers just because they can, I agree that if this is a production device then there's better choices, but if just fooling around or making something nostalgic then go for it.

Is it really that hard to follow either way? I get much more annoyed by the bickering by anal retentive people who'd rather bitch about it than just read the post or ignore it. Top post, bottom post, I don't care, it's just not that hard to follow either way.

I have brand new stuff in my junk box that has been obsolete for decades. If I have it, I'll use it, if only out of a sense of frugality. If I were building a commercial product, then availability would definitely be a primary consideration.

top posting are made by logical people, I have no idea what Karl said, I am not wearing my mouse out and wasteing all day to look through a lot of shit to see a few line somewhere hidden in the message, you are lucky I can read your reply without scrolling down.

Frank wrote:

You just 'top posted' btw !

Graham

Gee, John, just being difficult, or trying to start a war?

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

--
Who, me?^)

A 6802 is essentially a MC6800, MC6875 and a MC6810 integrated into one IC. The MC6802 intruction set is the same as the MC6800.

The MC6801/3 has increased instructions.

IF you really want a kicked up 6800, try opencores.org. There is a

6800 core that will drop into a Spartan 2 FPGA and runs at a E clock frequency of 12.5 MHz.

Today there are a few of the older 8 bit micros that have FPGA open source cores that can run at higher speeds than the originals. There is even a Z80 core that runs at 35Mhz.

james