Why the 6502

[Arlet]

BigDumbDinosaur wrote:

Yes, and at 20 MHz they perform at about the same level as the 65C02 running at 10 MHz. As always, you only get what you pay for.

There are several products using the eZ80 core, backwards compatible with Z80, runs up to 50MHz, improved cycle times.

[BigEd]

[Oops, several replies in between, unsurprisingly given BDD's claim]

BDD said something about relative performance, possibly calibrated against the 1970s offerings where a 4MHz Z80 would be a little faster than a 1MHz 6502 but not as fast as a 2MHz 6502. (See here and here)

I notice that the Z80 page on digikey says this:

Quote:

The Zilog Z80 CPU family of components are fourth-generation enhanced microprocessors with exceptional computational power. They offer higher system throughput and more efficient memory utilization than comparable second- and third-generation microprocessors. The speed offerings from 6–20 MHz suit a wide range of applications

which might mean that the cycle counts on the 20MHz parts are better than the historical 4MHz parts we're used to comparing to.

Whether or not that's so, I also notice that the eZ80 runs up to 50MHz and the datasheet says this:

Quote:

The eZ80 CPU is one of the fastest 8-bit CPUs available today, executing code up to four
times faster with zero wait-state memory than a standard Z80® operating at the same frequency.

which certainly means they are now using a clocking strategy more familiar to us 6502 types.

[floobydust]

BigDumbDinosaur wrote:

EugeneNine wrote:

Hmm, and seems to be still available as well. http://www.mouser.com/ProductDetail/ZiL ... 3LaLmSsNlp

Darn you, i didn't need another project

That part is more like a primitive microcontroller than microprocessor. It runs at a relatively sedate 6 MHz.

That's true, but Zilog (now part of IXYS) offer embedded microcontrollers which tend to compete with some of the Atmel microcontrollers. However, they also offer a CMOS Z80 processor available at clock rates up to 20MHz. Of course overall performance will vary compared to a 65C02 which can (over)clock around the same, but the Z80 isn't that cheap either. Still it's another option out there in the 8-bit world.

http://www.mouser.com/search/ProductDet ... 84C0020PEG

[Tor]

Yep.. http://www.mouser.com/Search/Refine.asp ... d=Z84C0020

By some accident I managed to acquire too many of them. More than I have projects for.

[cbmeeks]

BigDumbDinosaur wrote:

cbmeeks wrote:

That's not true. Z80's are still made, cheaper than 65C02's and run "OFFICIALLY" at up to 20MHz.

Yes, and at 20 MHz they perform at about the same level as the 65C02 running at 10 MHz. As always, you only get what you pay for.

Oh, I don't doubt the performance. I knew I would get a little flack for mentioning the Z80. But I mostly meant that it's certainly not "dead" and that it still has a huge following. But I prefer the 65C02 all the way.

BigDumbDinosaur wrote:

Years ago (mid-1970s, to be precise), I learned the Z80 assembly language as part of a work assignment. I used it for about six months and then got involved with the 6502, learning its assembly language. I have not touched a Z80 since around 1980, but continue to write code for the 6502 family. That should tell you something...

I find both languages to be quite enjoyable, actually. I program (from time to time) on the Propeller and I find its assembly to remind me of the Z80 assembly. Again, I enjoy the 65C02 MORE...I just don't hate the Z80.

BigDumbDinosaur wrote:

I don't know anyone who knows anything about the Z80. Most likely that has to do with the proliferation of the 6502 in so many products.

Well, that depends on the circle of people you associate with, I suppose. I know quite a few competent Z80 developers and the Colecovision homebrew scene is very active.

Again, I'm not knocking the 65C02 (it's my favorite)...just saying...

[whartung]

Is the 6502 easier at a hardware level to work with than a Z80? Especially on simpler hobby boards today with static ram and such, or are they essentially the same?

[BigEd]

Grant Searle has 6-chip designs for both Z80 and for 6502 so I think the usability must be very similar.
http://searle.hostei.com/grant/z80/SimpleZ80.html
http://searle.hostei.com/grant/6502/Simple6502.html

[cbmeeks]

BigEd wrote:

Grant Searle has 6-chip designs for both Z80 and for 6502 so I think the usability must be very similar.
http://searle.hostei.com/grant/z80/SimpleZ80.html
http://searle.hostei.com/grant/6502/Simple6502.html

I forgot about that site! Thanks.

[EugeneNine]

Links no worky, must have killed the site with all the extra traffic

Wasn't the z80 an 8085 instruction set? I had collected some but never made a project with them.
I did an 8085 around 1994 or 1993, still have most of it.


edit, z80 is based off the 8080 and the 8085 is based off the 8080, guess my memory isn't that great after a couple decades.

[BigEd]

No, Z80 was a superset improvement of the 8080. The 8085 was a single-supply version of the 8080, perhaps with a couple of tweaks. Remember when you needed multiple different voltages for your computer chips? Oh wait, we're back with that now.

[DavidL]

Works for me:
http://searle.hostei.com/grant/#MyZ80
http://searle.hostei.com/grant/#My6502

[EugeneNine]

BigEd wrote:

No, Z80 was a superset improvement of the 8080. The 8085 was a single-supply version of the 8080, perhaps with a couple of tweaks. Remember when you needed multiple different voltages for your computer chips? Oh wait, we're back with that now.

Yea, i went back and edited after. I still have my old 8085 book and notes from class.

[EugeneNine]

DavidL wrote:

Works for me:
http://searle.hostei.com/grant/#MyZ80
http://searle.hostei.com/grant/#My6502

must be something with AT&T, I have little issues here and there but it was $40 a month cheaper than anyone else in the area so I live with the issues.

[BigEd]

If you want a quick look at some web pages from a different endpoint, try
browserling.com

[Arlet]

If you get a Z80 based microcontroller, with internal memories and peripherals, it's even easier to get started.