Drew Sebastino wrote: koitsu wrote:
You're wanting information on the incomplete W65T32, or the 65C832
. It's a 65C816-compatible CPU. Read: it offers no new general-purpose registers (still stuck with A/X/Y), just that they can be 8/16/24/32-bit. You don't get any new instructions (still no bloody mul/div), no new addressing modes, no nothing. Blah.
I was thinking of the W65T32. I had never even heard of the 65C832, but it's about the least they could have done to upgrade the 65C816; I would have at least added multiply and divide instructions before I would have added 32 bit registers.
Although those are commonplace in modern processors, we might have to be careful what we ask for (if we were to get any more 65xx products). The 6502 was originally intended for embedded control, not desktop computers. Multiply can be done as quickly as the logic states can ripple through the multiple levels of logic, but that's not true of divide. What would a divide instruction do to one of the 6502's absolutely outstanding features which is interrupt performance which absolutely blows the doors off of something like the 68000? I've brought a dozen or so products to market using PIC16 microcontrollers, and never once have I needed a multiply instruction in them. Never. There was a time I needed a divide, but it was not in the part of the code that needed much performance, and it was ok to do it in a long, iterative routine. Also, the applications I put the PIC16's in had very little handling of quantities beyond 8 bits; IOW, 16- or 32-bit registers really would not have made any significant improvement on performance.
koitsu wrote:As with all the 65xxx "upgrades", the fact they're backwards-compatible is really what kills them.
I'm inclined to agree; maybe than other for the 65C832 which could have been designed for Apple IIGS backwards compatibility, it really doesn't make sense. You're not going to plug some 32bit processor into your C64.
No; the point would have been to make a machine (let's call it an Apple IIx for the sake of discussion) which can, while multitasking, run 32-bit IIx programs,at the same time with IIGS
programs that have not been recompiled for the new processor, at the same time with 8-bit Apple II programs which have also not been recompiled for the new processor. That would have been Apple's requirement, as it was with the IIGS
to be able to run stock Apple II programs. I'm not saying I agree with that philosophy. I can understand the desire to be able to tell the customer that his existing software investment is protected; but unless he's trading in his old computer, he can still run it yet have a new computer also whose designers took the opportunity to shed backward compatibility to gain other benefits.
(It's safe to say another commercial 65xx processor isn't getting made.)
Probably; but hobbyists are getting more and more expert with FPGAs, so it's not unrealistic to think we might have a high-performance upgrade someday. We don't need wafer-fab-scale investments anymore to do it.
Garth wrote:The following is from my links page though:
Excellent resource. I agree with one of the users in the forum topic you linked; turning zero page into on chip cache could do a lot to help mitigate the 65xx memory speed bottleneck.
I don't remember which topic that might have been. In most ways, that would help the '02; but remember "ZP" on the '816 can be moved around on the fly, placed anywhere in the first 64K of the memory map, and it doesn't even have to start on a page boundary. It can also be made to overlap the stack space (which is also free to occupy any part of the first 64K and can span many pages), allowing you to use all the ZP (actually direct-page, or DP) addressing modes in the stack area as well.
Drew Sebastino wrote:I'm not sure what this processor would have served, not with ARM having had taken over everything but the PC and server markets. I don't even know how WDC is still in business.
Most of WDC's business consists of licensing intellectual property to companies that put the '02 into custom ICs for dedicated jobs, in everything from toys to life support. One thing client companies find very attractive is the extremely low license fees compared to those of ARM. For an example, Mike Naberezny, owner of 6502.org, last year decapped the microcontroller in his VW Jetta instrument panel, for a project to try to integrate it with some other things for kind an "intelligence center" for the car. What he found was that the IC had a 65c02 in it. WDC's volumes have been huge (over a hundred million a year in recent years); but I perceive that the volumes are dropping and Bill Mensch is starting to see that the old marketing approach is going to have to change.
koitsu wrote:Like the 8-Bit Guy wanting to do some kind of computer that's driven by a 65816? Really dude? Who cares. Use ARM or something else and stop that nonsense. There are other more feasible full-featured (32-bit/64-bit) CPUs that there's no reason you'd need want a 65xx -- more capability, more general-purpose registers
Note that more general-purpose registers does not necessarily mean you'll have better performance. Sophie Wilson, chief architect of the ARM processor, said, "an 8MHz 32016 was completely trounced in performance terms by a 4MHz 6502." (The 32016 was National's 32-bit processor, having 15 registers, including 8 general-purpose 32-bit registers.)
and are a lot more versatile support-wise (like, for example, a decent C compiler).
It should be much easier to develop a decent C compiler for existing 65xx processors than to develop a bigger processor. I can see "The 8-Bit Guy's" goal though. A friend writes, "The often-noted quality of the eight bit computers of 30 years ago was that they encouraged recreational software development. I had worked with computers for nearly 14 years before I bought a Commodore 64 in 1983, but had never had fun writing code until I learned the machine architecture of the 64, got an assembler and dove in." A problem with PCs or smartphones or similar is that the non-computer-engineer has no hope of ever understanding them or having full control. And as soon as you put something like a RPi in a supposedly retro machine, people will put all the regular bloatware on it again and defeat the purpose of an efficient computer that the user can fully understand and control.
I like professional programmer Samuel Falvo's philosophies laid out in these two essays of his: