Talk:WDC 65C816

Title change and merge: "65816 Microprocessor" + "65802 Microprocessor" --> "WDC 65816/65802"

Why the name change? In short: because <company name> <processor name>, where <company name> belongs to the originating company, is the de facto standard for microprocessor articles in WKP. Note that this also applies to processors which are/have been second-sourced (i.e., manufactured by one or more companies other than the originating one).

Rationale for the article merge: It seemed natural, as the 65802 is a straighforwardly "feature-reduced" version of the 65816. The 65816 is listed first in the title, as that processor is the main variant of the two. --Wernher 14:54, 16 July 2005 (UTC)

Source of performance statement wanted

I removed the following from the article: "It worked at 1,5 mips." Could the contributor or others please give a source of performance figures for the 65816/802 processors? It would be an OK addition to the article. --Wernher 14:12, 17 October 2005 (UTC)

The performance of the 65C816 measured in MIPS will be basically the same as in 6502, just the 65C816 can work with much higher clock speeds. here (the snapshot on the right) is an example benchmark for a 14 MHz 65C816, and it averages at 3,1 MIPS. The result could be better, but memory writes, which are a part of the test, are slow on that machine. 82.210.159.30 12:23, 4 June 2006 (UTC)

Advertising removed

The recently added material that looked like direct advertising from WDC's website was removed by me. The feature list, which I wikified, gives all the information needed, in a more neutral manner. --Wernher 15:12, 27 February 2006 (UTC)

SNES 65816

It would be nice to know how exactly the SNES's "customised" 65816 differs. According to SA-1 chip, it's a (Ricoh?) 5a22. It seems that there might not be much difference from a software point of view, though [1]. BTW, {{MOS CPU}} has an entry for "Ricoh 5a22"... If someone can confirm that this is really the SNES CPU, we can have that redirect here. --StuartBrady 23:51, 7 March 2006 (UTC)

The SNES CPU is a Ricoh 5A22, which is based on the 65c816; if there are any differences in the core, I don't know about it. However, it has a number of additional features in the package: DMA logic, joypad reading circuitry, interrupt generation circuitry, multiplication and division hardware, an additional address bus, and a variable clock divisor based on the memory region accessed. The SA-1 is also based on the 65c816 with additional features: DMA logic, interrupt generation circuitry, internal RAM, additional arithmetic circuits, bitmap format conversion circuitry, a barrel shifter for variable data access of 1-16 bits, access collision avoidance, memory mapping circuitry, and an integrated version of Nintendo's CIC lockout chip. Anomie 16:21, 21 October 2007 (UTC)

SuperCPU

According to List of home computers by category, there was a (third party?) external CMD SuperCPU accelerator for the Commodore 64 and C128. Would that be worth mentioning and if so, where? --StuartBrady 00:06, 14 March 2006 (UTC)

Successor to 6502 or 6510?

It seems to me that this 65816/65802 builds upon, not the 6502 but its successor the 6510 (which has more capability). - Theaveng 10:48, 21 October 2007 (UTC)

Not so! The 6510 did not have "more capability," whatever that means. It (the 6510) had the exact same instruction set as the 6502, complete with the same limitations and bugs, e.g., the malfunctioning JMP(xxFF) problem. Also, the 6510, like the 6502, was an NMOS part and was only available in two clock speeds.

The 65816/65802 have always been CMOS parts, are available in much higher clock speeds than the 6510, and like the 65C02, work correctly. JMP(xxFF) behaves as it should, a BRK executed at the same time an IRQ occurs is honored, etc.

Also, the CMOS lineage actually existed before the 6510. Western Design Center and Rockwell were both shipping 65C02s in 1981. I know, because I used one to modify a CBM 8000 machine.

BDD (talk) 06:38, 17 December 2007 (UTC)

The 6510 has a 6 bit i/o port which the 6502 lacks, and (afaik) was not carried over to the 65816/65802 (though some of the variants have such things).
—überRegenbogen (talk) 19:28, 8 January 2009 (UTC)

It seems to me the the 65816 is the successor to the 65C02 rather than the 6502 or its variants, while the 65802 is a crippled variant of the 65816. Though YMMV. — Preceding unsigned comment added by 98.160.239.73 (talk) 22:18, 14 February 2014 (UTC)

Article update

Some time in the not-to-distant future I am going to edit this article to be more in line with similar articles for other members of the 6502 family.  Although the 65C816 has the "heart" of a 65C02, it is sufficiently advanced over its eight bit counterpart to warrant a more in-depth treatment, especially on the hardware features that only it has (e.g., the ABORT hardware interrupt).  The present article is mostly a recapitulation of the bullet points from WDC's product page and doesn't give the reader much information beyond the MPU's development history and the systems in which it was/is used.

Bigdumbdinosaur (talk) 04:13, 24 October 2012 (UTC)

Requested move 23 July 2019

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: Moved – Unopposed if I read it correctly. (non-admin closure) Dicklyon (talk) 01:04, 11 August 2019 (UTC)

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WDC 65816 → WDC 65C816 – Rename article to include letter "C" similar to 3 other WDC articles: WDC 65C02, WDC 65C134, WDC 65C265. • Sbmeirow • Talk • 07:30, 23 July 2019 (UTC) --Relisting.  — Amakuru (talk) 16:35, 2 August 2019 (UTC)

Did the name actually include the "C" in the beginning? I can find lots of references from the era that do not include the C. It appears to have become more common later. Maury Markowitz (talk) 15:40, 2 August 2019 (UTC)

There are references to both on the internet, so what, but it is currently known with the "C" as 65C816. The old name is deprecated, so it should be treated as such on Wikipedia, though both should be included in the article. If you feel that without "C" is correct, then please show me photos of actual IC chips that don't have LETTER(S) between the "65" and "816", seriously please show the evindence, otherwise the old name is moot for the article title. • Sbmeirow • Talk • 18:57, 2 August 2019 (UTC)

Well where does it say that in the article? After all, it's trivially easy to find Bill himself calling it the 65816, but what would he know? Maury Markowitz (talk) 14:40, 5 August 2019 (UTC)

1) In 2019, why should a "C" not be added to the 65816 article name, though WDC 65C02, WDC 65C134, WDC 65C265 articles all have "C" in their name, as well as at the official webpage? • Sbmeirow • Talk • 23:48, 5 August 2019 (UTC)

2) Where are photos of 65816 chips without a "C"? Show me proof! • Sbmeirow • Talk • 23:48, 5 August 2019 (UTC)

I'm fine with the move, I'm asking where in the article we talk about the change in naming. You say "both should be included in the article", but that is not actually the case as it stands. Maury Markowitz (talk) 11:18, 7 August 2019 (UTC)

• Support move: See [ http://www.6502.org/documents/datasheets/wdc/older/wdc_w65c265s_mar_2000.pdf ]. --Guy Macon (talk) 00:35, 6 August 2019 (UTC)

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The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Venerable

Use of "venerable" to describe the NMOS 6502 is actually quite appropriate once one considers what "venerable" means:

Definition of venerable

1a : calling forth respect through age, character, and attainments

b : impressive by reason of age

Above was copied from the Merriam-Webster on-line dictionary of the English language.

I restored the phrase "venerable MOS Technology 6502 NMOS MPU" because the 6502 indeed meets the requirements of "age, character, and attainments." Also, that word has been part of the article's intro for nearly 10 years. I fail to see any good reason to remove it.

216.152.18.132 (talk) 01:15, 18 June 2022 (UTC)

24-bit addressing

From the intro:

Despite 24-bit addressing, the 65816 isn't a true 24-bit computer. Programs still operate in 64K chunks since registers are 16-bit. To access other parts of internal memory a technique similar to bank switching is needed.

The highlighted text is completely false! Addressing constraints apply only to program execution, not data accesses, and there is no “bank switching.”

Contiguous program code cannot span banks without the use of JML and/or JSL, only because when the program counter (PC) wraps, the program bank (PB) will not increment (which characteristic, in my opinion, was an unnecessary constraint that was apparently the result of Apple’s meddling in the 65C816 design process). It has nothing to do with register sizes. A program whose size is greater than 64KB can be executed if JML and/or JSL are used to transfer control between banks.

Data fetches and stores can be bank-aware using 16-bit addressing modes—same as with the 6502/65C02, or bank-agnostic using 24-bit “long” addressing modes. 16-bit addressing is generally one clock cycle faster per memory access, but long addressing can fetch from or store to anywhere in the 16MB space.

I am removing the subject text from the article.

Bigdumbdinosaur (talk) 20:26, 23 May 2023 (UTC)

I would have liked to thank you for improving the accuracy of our article -expert attention is always welcome- Bigdumbdinosaur, but I notice you removed much more from the article than what you said you would. The article should, in my opinion, explain what differentiates the 65816 from a true 24-bit processor, i.e. explain the limitations, and ideally, to do so in a reader-accessible manner; i.e. as non-technically as possible. (Precise details only the initiated can appreciate can always be covered later in the article). Also, you removed the part where the processor is contrasted to the MC68000 which all three major suppliers of home computers opted for, including a very valuable historical tidbit (the BYTE interview with the Woz). In order for that piece to fit, the average reader should leave our article with some understanding why that decision was made. Here's hoping you're willing to discuss further improvements to the article. Regards, CapnZapp (talk) 05:20, 24 May 2023 (UTC)

I'll go ahead and try to reincorporate the cut text into the article as per above. Any expert is welcome to attend the article. CapnZapp (talk) 13:33, 29 May 2023 (UTC)

W65C802

Per WP:LEAD Apart from basic facts, significant information should not appear in the lead if it is not covered in the remainder of the article.

In other words, we currently talk about the 65802... but only in the lead. Let's avoid a {{lead extra info}} tag. CapnZapp (talk) 05:27, 24 May 2023 (UTC)

WDC 65C832 citation

Perchance this discussion might help: Stack Exchange CapnZapp (talk) 05:43, 24 July 2023 (UTC)

The 65C832 concept was hatched in the latter 1980s and was essentially DOA by the late 1990s.  The 65C832, at best, was a proposed solution in search of an undefined problem.  Given that little-to-no design work was done on it before it was permanently dropped, I see no good reason to even mention it.

216.152.18.132 (talk) 18:31, 15 December 2023 (UTC)

24-bit claim

You're gonna need to discuss my edit comment ("that section isn't there to counter some claim. It is there in order to explain and contrast. Feel free to improve the phrasing, but don't throw out the baby with the bathwater") and not just repeat your revert, 216.152.18.132.

Please begin by understanding why I want that text there. Then you are free to change the phrasing. Thank you CapnZapp (talk) 20:40, 29 January 2024 (UTC)

Your argument is wrong.  No one has ever made a claim that the 65C816 is a 24-bit microprocessor.

216.152.18.132 (talk) 01:38, 14 February 2024 (UTC)

I am not suggesting anyone has. CapnZapp (talk) 05:23, 14 February 2024 (UTC)