Hey guys. So, this isn't 6502 specific, but as I am very interested in cpu design, I intend to design BETTER processors that have fixed previous problems, but the issue is naming. Believe it or not, that is probably the main thing stopping me from just starting a new processor that is better than the 65S4ME. Why make a new one instead of fix the old one? TBH its just my personal preference, I already have worked quite a bit on the 65S4ME and would prefer to start new. Take more consideration into things... but back to the point, I need a name for it. I need names for the processors I intend to create in the future. I guess what I'm asking for is ideas on names and ideas on how to create good names (recursive acronyms FTW). What do you all think?

Hmm, is the name more important, then the product? It is probably out opinion that it's better to create a new thing the fixing problems in an old version. For a personal project this might be a good idea, but if you think about the real life, it's not. Why?
Well, we are talking about a processor, that in all cases will be a part of a more complex product. By creating a complete new processor, you may change design and layout compared to the old version. That causes a lot of trouble if somebody used the old version in his system and now wants to get the new version working without the need of redesigning the whole system and rewriting all the software. If you are a company, you would disappear from the market before you've finished your second design.
Don't get me wrong. It is totally OK if you're doing this for your private project. It is only up to you how far you go.
But what are the reasons for stopping with your 64S4ME? What are the problems and the gaps that make you stuck with it? How far did you come with the emulator for the 65S4ME? Can you show some code or is the "design page" the last thing that happend?
Do you know the Second System Syndrome? (http://en.wikipedia.org/wiki/Second-system_effect)

Mario.

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How should I know what I think, until I hear what I've said.

Like you said, for a personal project its okay...
Well, I just think that I want to rethink the instruction set and addressing modes. Thats basically it. I mean, I got pretty far actually. This:



Practically 6502 code, would create a basic echo program..

I did not create things like indexed addressing which was a large issue. As far as the assembler goes, it was minimal and very buggy but it worked...

Overall, considering the things I've learned in my time here, I'm just not really all that happy with the way it was working out. I mean it worked... but I think it could be a lot better and like I said, I would just really prefer to redesign it for two reasons, 1. i just would, 2. i enjoy the design process anyway.

*reads*

Hmmmm...

Way back when, we used to call this "creeping featurism."

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

I had much more fun reading the 'Talk' section ... it's a bit sad to me that the main article was
edited to death, even if it had problems.

Mike

Yeah, you aren't inconveniencing anyone by starting fresh, using your new knowledge and previous
experiences as a guide.

BTW, why do your lda instructions use absolute addressing, and your sta instructions use immediate
addressing to perform the same style of access? My 65m32 allows store immediates, but only to
modify a value during a register-to-register transfer ... it's the same as a load immediate register-to-
register (which also allows a numeric modifier), but it doesn't affect any flags, while load usually does.

Mike

- TBH I don't really know what you mean... ??

As far as starting fresh, I suppose I should keep going with the 65S4ME... the benefit of that is that it already has a decent name
But really, I do want to EVENTUALLY create a new processor. I guess I should "finish" this one and after thats over, work on a new processor which is "a step up"?

No one would blame you for abandoning something that doesn't 'flip your switch' anymore. It's a free
country, and most of us are adults here ... take your project in whatever direction suits you, and we'll
try to help.

Regarding store immediate:

No-one is telling you how to implement your assembly language (mine has clearly caused some
head-scratching around here), but this sample shows the standard syntax for the assemblers
that most of us old farts know and love. The '#' operand prefix assembles into an immediate
instruction (one that takes the operand at face-value), and the absence of the '#' prefix assembles
into an absolute or direct-page instruction (one that uses the operand to specify a memory address).
When the cpu sees an immediate-mode opcode, it loads the following value 'directly' into the register.
When the cpu sees an absolute-mode opcode, it loads the following value into a memory access
register, basically using the value as a pointer into memory. If you look at any source code for
most processors, you will find that something like sta #1234 is notably absent, since you are trying
to do the high-level language equivalent 1234 = a. In my assembly language, this is not an error,
but just one of many no-ops, since there is a hidden default register z embedded within the operand.
a + 1234 is assigned to register z, and the result is discarded at the next instruction fetch.

I hope that this explanation makes more sense.

Mike

[Edit: I just remembered something about the 6800 ... staa #0 was not available in the assembly
language, but there was an undocumented op-code slot for it. If you executed this two-byte instruction,
the 6800 would do its best to comply, by storing the run-time contents of accumulator a after the 0
operand in the second byte of the instruction, and continuing execution at the byte after that ... kinky!!
Naturally, this only 'worked' if the instruction was in RAM.]

What about redesigning? I mean.. I just think it would be easier for me to make the changes I want to make if I started from scratch... so, redesign it...

It depends on a few things that only you can identify. An analogy: you are painting a large, beautiful
nature scene in oil, and you screw up a large, important part of the foreground. Do you toss the whole
painting and start over from scratch with a fresh, blank canvas, or do you try to scrape off the screw-up
and paint over it, hoping that nobody will notice any evidence of the correction in the final viewing?

In other words, it depends on how good you are at covering errors, how picky your potential viewers
are, and how it is going to make you feel when you look at the finished product, and find your eyes
always being drawn to the spot that you 'fixed'.

Mike

Well, in my perspective.. this is a "private" personal project and I don't think it will have much or any bad results... so i'll do it.