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Photo of 6800 board

Hi. Why is there a photo of a 6800 demonstration board? Although some of the same engineers designed both, I don't think it's relevant and it should be removed. - Richard Cavell (talk) 17:18, 12 January 2017 (UTC)[reply]

You mean the “Motorola 6800 demonstration board built by Chuck Peddle” in the “Origins at Motorola” section. This shows that Chuck Peddle was very familiar with the 6800 processor while he worked at Motorola. There was a bit of a dust up about Chuck copying the 6800 design. The board is notable and is on display at the Computer History Museum in Mountain View, California. -- SWTPC6800 (talk) 22:56, 13 January 2017 (UTC)[reply]
Fine, but why is it in the MOS (not Motorola) 6502 (not 6800) article? The same engineer designed the Pontiac GTO and the Chevy Vega, but the Vega article doesn't have a picture of the GTO. Jeh (talk) 23:12, 13 January 2017 (UTC)[reply]
The GTO engineers did not take General Motors documents to a new company to design a lookalike car. Chuck Paddle actually built this prototype board. It shows the background experience in microprocessors of one on the 6502 designers. -- SWTPC6800 (talk) 03:17, 14 January 2017 (UTC)[reply]
I don't think that's sufficient reason. Articles should be about their subjects. The subject here is the 6502, not the 6800. Chuck Peddle is a subtopic within this article it but this demo board shows his work on a different project for another company. Per the 6800 article, he didn't design the 6800 architecture; his role in the 6502 project was different. Nobody is saying the board isn't notable or isn't worth a picture, only that its picture doesn't really add to the presentation of facts in this article. I agree that the demo board has some relationship to the 6502, but that relationship is too tenuous to support the picture being here. Why isn't there a picture of an early demo board for the 6502? Or maybe of the justly famous KIM-1? Conversely, why isn't this picture in the 6800 article? Jeh (talk) 02:08, 17 January 2017 (UTC)[reply]
The Apple I has jumpers to select 6502 or 6800, the pinouts are very close. I suspect other boards were designed to work for either chip. Gah4 (talk) 20:57, 1 March 2018 (UTC)[reply]

Transistor count

For NMOS (and PMOS) logic, depletion mode transistors are used in place of resistors. Since they don't have any transistor function, some might not count them. That seems about the right order of magnitude to make up the difference between the two numbers, but I don't know which number is traditionally used. Gah4 (talk) 18:19, 1 May 2017 (UTC)[reply]

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How many have been produced so far?

According to minute 3:00 of this talk on YouTube, more than 10 billion were produced by one company alone. It would be nice to have a proper source for production numbers (presumably of the entire 65xx family) so the information can be included in the article.

Name of stack pointer

"SP" is common usage for other machines, but the hardware data sheet agrees with the text, which refers to it as "S". TEDickey (talk) 02:11, 8 November 2019 (UTC)[reply]

OK although my extremely dim recollection is that "SP" was common. At any rate, whoever created the table certainly thought "SP" was right because they helpfully bolded the full name (Stack Pointer) in the same manner done for PC. It is true that the instruction set includes TXS which uses S and PHA is defined in terms of S. Johnuniq (talk) 04:13, 8 November 2019 (UTC)[reply]
The designers needed registers to have single-letter name if they're to be used in the instruction mnemonics that they'd fixed at three letters. PC isn't so they could go with convention. SP is so that may be why it's only S. My opinion of the datasheet at the time was that two letter names were clearly used for two-byte registers and one letter for single byte registers. That might be led by my Z80 experience, as it used that naming scheme. But so might the 6502 designers/datasheet-authors, who would have known of the 8080 which used the same register naming scheme. I remember it described in many places as a 16-bit register with rollover in the low byte and always 01h in the high byte. Either way, we should go with what the datasheet and the instruction set use rather than anyone's recollected opinion, otherwise we're writing conjecture.ToaneeM (talk) 09:19, 9 November 2019 (UTC)[reply]
Of course, but the data sheet nowhere says "the stack pointer register is known as S". I listed what it says, and it simply uses S in a couple of places where extreme brevity was required. Johnuniq (talk) 02:31, 10 November 2019 (UTC)[reply]
Page 31 of the hardware manual lists the registers and calls it S there as well, without the need for brevity TEDickey (talk) 11:27, 10 November 2019 (UTC)[reply]
That sounds conclusive: S it is, of course.ToaneeM (talk) 16:43, 10 November 2019 (UTC)[reply]
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