6502.org Forum  Projects  Code  Documents  Tools  Forum
It is currently Thu Mar 28, 2024 10:09 am

All times are UTC




Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject:
PostPosted: Wed Oct 27, 2010 10:57 pm 
Offline
User avatar

Joined: Fri Aug 30, 2002 1:09 am
Posts: 8412
Location: Southern California
Quote:
I don't want to look as being too critic about the old 6502. It was a remarkable design. Probably the best MIPS/$ and MIPS/#transistor of its time.

Since you are new here, I will repeat that it is still selling in the quantity of hundreds of millions of units per year; but most of them are invisible, being at the heart of custom ICs, the fastest of them running over 200MHz, able to handle up to about ten million interrupts per second.  WDC's primary business is licensing IP, not selling hardware.

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Wed Oct 27, 2010 11:31 pm 
Offline

Joined: Mon Mar 02, 2009 7:27 pm
Posts: 3258
Location: NC, USA
A 200MHz 6502?!.... I heard it before and I'm sure I'll hear it again, but jeez that speed is sweet for a 6502!

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Oct 28, 2010 4:32 am 
Offline

Joined: Sat Jan 04, 2003 10:03 pm
Posts: 1706
BAH! That's nothing! You just wait until I finish my optical 6502 clone...

;)

(j/k; but, were such a device indeed to exist, its maximum speed would be limited the slower of light propegation delay (about 1 ft per nanosecond) of the longest inter-gate distance, or the element with the highest index of refraction. An interesting topic for another day...)


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Oct 28, 2010 5:59 am 
Offline
User avatar

Joined: Thu May 28, 2009 9:46 pm
Posts: 8114
Location: Midwestern USA
ElEctric_EyE wrote:
A 200MHz 6502?!.... I heard it before and I'm sure I'll hear it again, but jeez that speed is sweet for a 6502!

Even at a mere 20 MHz, the old 65C02 clips right along. The '816 does even better when fully exploited.

_________________
x86?  We ain't got no x86.  We don't NEED no stinking x86!


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Thu Oct 28, 2010 11:08 pm 
Offline

Joined: Sat Jan 04, 2003 10:03 pm
Posts: 1706
Indeed, and I think I even have a working conceptual design for a Hardware Object-Oriented Programming Language Accelerator (HOOPLA -- yes, it's intentional. If AmigaOS can get away with BOOPSI, I can get away with HOOPLA!!).

Why must I have so many projects? Why can I not finish one before starting another? :)


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Fri Oct 29, 2010 2:20 am 
Offline

Joined: Mon Mar 02, 2009 7:27 pm
Posts: 3258
Location: NC, USA
kc5tja wrote:
...(j/k; but, were such a device indeed to exist, its maximum speed would be limited the slower of light propegation delay (about 1 ft per nanosecond) of the longest inter-gate distance, or the element with the highest index of refraction...)


You are thinking within the relativity Laws of Einstein..

Think of a black hole now. Those relativity laws are now under the Laws of electromagnetism, controlling light... a hyper galactic light coil... as opposed to a speaker coil, same principle i think

Ah jeez you got me started. This is WAY off-topic. My apologies

:lol: :lol: :lol: :lol: :lol: :lol: :lol:

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Fri Oct 29, 2010 10:19 am 
Offline

Joined: Mon Mar 02, 2009 7:27 pm
Posts: 3258
Location: NC, USA
I was going on about an electromagnetic optical computer. Anyway, I happened across this article this morning:

http://news.yahoo.com/s/afp/20101028/tc ... ogyitworld

China has the fastest computer @2507 trillion calculations/sec, using IC's from the US!

_________________
65Org16:https://github.com/ElEctric-EyE/verilog-6502


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Fri Oct 29, 2010 11:14 am 
Offline

Joined: Tue Jul 05, 2005 7:08 pm
Posts: 986
Location: near Heidelberg, Germany
kc5tja wrote:
Why must I have so many projects? Why can I not finish one before starting another? :)


So true, so true.... :-)

André


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sat Oct 30, 2010 8:53 pm 
Offline
User avatar

Joined: Thu Dec 11, 2008 1:28 pm
Posts: 10760
Location: England
jesari wrote:
Thanks for the explanation about the 6502 pipelining. I must admit there is some pipelining: last steps of execution in parallel with next instruction fetch. I think this is not always possible, but it can be done on some instructions, and is far from those pipelines found on typical RISC processors.

Hi Jesari
A few minutes ago we updated the pre-release simulator on the 6502.org website. It's even faster than before, and you can visit a URL like
http://visual6502.org/JSSim/expert.html ... =60&r=0020
to run a program of your choice and see the values moving between the various registers - including registers not visible to the programmer.

You could instead run the included short demo program with
http://visual6502.org/JSSim/expert.html ... loglevel=5

This is the first version to fix the timing control state signals, so you can see the state of the machine: it's not a shift register, but something like it. You should be able to see the overlap of successive instructions in a lot of cases.

You might want to arm yourself with Donald Hanson's big block diagram - many of the same names are used.

If you turn on the chip layout view, you'll find you can also zoom in and explore the values of any signals.

Hope you find it interesting! (Thanks to Barry, Brian and Greg, as always.)

Cheers
Ed

Edit: update links, from pre-production to released version


Last edited by BigEd on Wed Nov 10, 2010 8:33 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sat Oct 30, 2010 9:12 pm 
Offline

Joined: Sat Jan 04, 2003 10:03 pm
Posts: 1706
BigEd wrote:
so you can see the state of the machine: it's not a shift register, but something like it.


I find it timely that you mention this; as I woke up this morning, I decided to work through my old bus synchronization circuitry, asking myself, "What if I represented state as a binary number instead of (in essence) a ring counter?" It's doable, but logic becomes much more complex (6-input AND gates versus 2- or 3-inputs).

Interestingly, you are free to assert multiple states at once, as the 6502 does, if you keep your states fully decoded at all times. You can't do that by representing states as a single number. This is essential for supporting pipelining too.

People can really learn a lot by observing how the 6502 handles its state progression. This is a HUGE service to the electrical engineering community as a whole, and 6502 enthusiasts in specific.


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Mar 13, 2011 11:42 am 
Offline

Joined: Sun Mar 13, 2011 4:58 am
Posts: 17
Location: Rindge NH USA
I think, as one of the above posters put it, the 6502 should be classified as "pre-RISC", or as I'd put it "proto-RISC". It definitely doesn't meet the classical definition of RISC, but it was developed before RISC (as such) existed.

That said, it does have some similarities to later RISC processors. Such as a small instruction set, hardwired decode logic, pipelining (even if limited), and a precursor to large register sets in the form of the zero page.

But I think the most important point that makes it RISC-esque is that the ISA is elegant. It's my favorite ISA. The only complaint I've got is that the X and Y registers aren't orthogonal. When I'm in the zone, I can fit the ISA in my headspace, which is a good thing.

_________________
@loop: lda (src),y — sta (dst),y — iny — bne @loop — inc src+1 — inc dst+1 — dex — bne @loop


Top
 Profile  
Reply with quote  
 Post subject:
PostPosted: Sun Mar 13, 2011 8:31 pm 
Offline

Joined: Tue Jul 05, 2005 7:08 pm
Posts: 986
Location: near Heidelberg, Germany
Karatorian wrote:
But I think the most important point that makes it RISC-esque is that the ISA is elegant. It's my favorite ISA. The only complaint I've got is that the X and Y registers aren't orthogonal. When I'm in the zone, I can fit the ISA in my headspace, which is a good thing.


Yes, that is one real good thing. I remember an interview with Chuck Peddle where he said that they talked to programmers what they needed for an efficient instruction set, which the MOS team optimized, where other CPU designers more worked from theoretical considerations. And that approach really shows.

In fact I think the ISA is so elegant that I decided to extend it to a more modern approach. See my 65k project: http://www.6502.org/users/andre/65k/index.html

André


Top
 Profile  
Reply with quote  
 Post subject: Re: CISC or RISC
PostPosted: Thu Dec 07, 2023 11:27 pm 
Offline

Joined: Thu Dec 07, 2023 11:23 pm
Posts: 1
I would argue that the best answer is it's a pre-RISC CPU. The distinction RISC <-> CISC makes sense from the time on when RISC was coined as a movement to counter CISC complexity. Since the 6502 family never suffered from complexity issues, and doesn't use micro-code, I prefer the term "pre-RISC" to "pre-CISC", but you may use either for symmetry.


Top
 Profile  
Reply with quote  
 Post subject: Re: CISC or RISC
PostPosted: Sat Dec 09, 2023 4:31 am 
Offline
User avatar

Joined: Fri Dec 11, 2009 3:50 pm
Posts: 3327
Location: Ontario, Canada
leidner wrote:
the 6502 family never suffered from complexity issues
A wryly entertaining observation!

Welcome, leidner :)

-- Jeff

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 44 posts ]  Go to page Previous  1, 2, 3

All times are UTC


Who is online

Users browsing this forum: Google [Bot] and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: