i could, but why/how would having MUL and DIV effect compatibility? the B Register is also used for 16 bit arithmetics, and they don't change the function of any existing Instructions...
so i don't really see the point of doing that unless i were to make an addon/Co-Prcoessor to an existing 6502 CPU

_________________
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?

My 6809 computer had a special socket on the CPU board for a 9511 or 9512 math processor.

http://www.cpushack.com/2010/09/23/arit ... n-and-now/

SWTPC also sold the MP-N, a card containing a National Semiconductor calculator chip.

https://deramp.com/swtpc.com/MP_N/MP_N_Index.htm

I see your point, but it makes it sound like i should give up on the project since the '816 already seems to do very similar things...
and to be honest i'm natually prone to abandon projects like these... manually programming nearly 256 instructions really isn't appealing to noone's surprise.



to be honest i'd rather just sit down with Chromatix to design and build a Sophisticated Memory mapped Co-Processor than to store 2MB of LUTs.

Don't be put off by other things! The '816 has nothing to do with your project. You have you own preferences and your own vision: what's important and how to do it.

_________________
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?

makes me think that making a Co-Processor for the 65816 to enhance it's functions would seem more worth while than starting from scratch....
but then again, i have never made a Co-Processor nor have i worked with the 816 before...

I'm currently just very demotivated to continue this... I'll sleep over it.

The '816 is not a great example for a new project, because a new project won't have the same constraints or cost functions.

Proxy, it would be a great shame to see you retire from this project.

And for everyone else, including me, this could be a good lesson in the cost of relating new ideas always back to the same old ideas. Much better to read carefully where someone is coming from and what they are trying to do. Write for your audience, and aim to be encouraging. Adding a smiley does not entirely defuse a grenade.

Ed, don't you think saying that on a 6502 forum is a bit out of place? Of the entire 6502 family, the '816 is by far the most capable and most adaptable to the things that the 6502/65C02 don't handle well. If someone like me who had no prior experience scratch-designing a computer could get an '816-powered machine running on the first try, Proxy should have no trouble doing the same. Having working hardware on the bench beats having theoretical hardware on a sheet of paper every time. And at the risk of redundancy, it's always good to keep in mind that this is a 6502 forum.


Virtually everything in technology today relates back to old ideas. In fact, from my vantage point of having been involved with computers for so long, I don't see all that much that is truly new. Yes, processors are faster than ever (although that curve is starting to flatten a bit), hard drives are bigger and faster, programming tools are more powerful and less taxing to use, etc. However, the basic technology is not much different than what it was 50 years ago when I was writing machine code for Post Office letter sorting computers. Or to put it in automotive terms, despite all the technological advances that have occurred in motor vehicles, we still have steering wheels, gear shift levers and brake pedals in our cars, same as what my grandparents had in their cars in the 1920s and 1930s.

A fellow I worked for for a number of years had some good aphorisms that apply here:

In order to go forward you have to learn from the past.

Evolution, not revolution.

Don't reinvent the wheel!

And of course there is Santayana's timeless advice...


I've read most of this topic and my impression—pardon me for being blunt—is we have yet another person who thinks he will reinvent the 6502. I hate to discourage anyone in the world of technology, but the 6502/65C02/65C816 family evolved as it did for some excellent reasons. Yes, there are things that could be different or better. That is true of virtually everything man-made.

That said, when someone suddenly gets a notion to add all sorts of bells and whistles to what is basically a (to more-or-less quote Bill Mensch) "a cost-sensitive processor" I have to ask them if they have studied the design they are aiming to make over. Using an aviation analogy, suppose I yank the engine, wings and tail off a Beech D17 and replace them with the engine, wings and tail from a P51 Mustang. Would my Beech D17 still be a Beech D17? Or, would it be a P51? (Would it even fly? Anyone brave enough to find out? ) The answer to questions 1 and 2 would be no, right? That being the case, would you call something that has features that were never part of a 6502 a 6502?

Much of what I have read in this topic is—and again I will be blunt—fantasy. Why encourage someone to take a path that likely will lead them to failure? Again using an aviation analogy, why not just encourage would-be aviators who have only a limited knowledge of aerodynamics to fully extend their arms, leap off a cliff and start flapping like hell? Even though just about everybody who has tried that has ended up punching a hole in the ground with their head, we can't be discouraging such folly, can we?


Don't be discouraged. Losing motivation is often a natural response to realizing that you may have taken on more than you can handle at present. Perhaps a period of goal-evaluation would be useful. You have bitten off a very large chunk of meat that is proving to be difficult to chew and swallow. It's good to have lofty goals. However, it's even better to have realistic ones.

BTW, designing a math coprocessor for the 65C816 could make you rich and famous...well, famous, if anything.

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

It was unfortunate that Apple insisted on legacy compatibility and also on continuing to use that weird disk interface that depended on a bus anomaly. But computing is littered with stories like that, and as you noted, the ][GS likely would have done poorly without some backward compatibility.

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

No, BDD, it's not appropriate always to push the 816 as the best solution, and it's not consensus that it is a marvellous product.

If you've managed to discourage someone, it's a bit late to re-iterate all your points and then tell someone not to be discouraged. Far better to learn the lesson.

There are already threads about how and in what ways the 816 is an appropriate choice. The polite thing to do, when you have a hobby horse such as this, if you can't bear not to mention your favourite thing, is to post a simple link to a previous thread where all these points have been made.

This forum has a good reputation for being welcoming and helpful and good natured. Let's not spoil it by pushing every thread into the same direction.

Don't worry i get discouraged very quickly by about anything.

I'll still finish this though. mostly for the sake of finishing a project.

I have decided on the Instructions i want to add, there are 93 new opcodes. bringing the total amount to 244, leaving a total of 12 opcodes empty for any future use.
today i'll try to program them all in, once done i'll make an Opcode table that not only shows the opcodes but also compares their cycle times with the original instruction set.

_________________
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?

One of WDC's soft core models has a memory mapped maths accelerator. You write the multiplier and multiplicand to memory registers and read the product from another location. You could do the same for division.

_________________
Andrew Jacobs
6502 & PIC Stuff - http://www.obelisk.me.uk/
Cross-Platform 6502/65C02/65816 Macro Assembler - http://www.obelisk.me.uk/dev65/
Open Source Projects - https://github.com/andrew-jacobs

The C256Foenix project (which may or may not still be going) also has memory-mapped maths acceleration: https://wiki.c256foenix.com/index.php?title=GABE. The floating-point coprocessor looks fairly neat.