Talk:MOS Technology 6502

Contents

1 2A03's extra A/V features 2 6501<>6502 slot converters? 3 Clock multiplication 4 Terminator  6502 code 5 MOS Technology?

2A03's extra A/V features

The 2A03 lacked the 6502's decimal mode but added 23 memory-mapped registers for sound generation, object drawing, and joypad reading.

This can't be correct. All 6502 based systems use memory mapped IO, as the 6502 doesn't provide any other means of doing IO. All the sound and specialized graphics are provided by other specialized chips. --jay kominek (i'm not outright correcting this as there is a small chance that it is correct. comments?)

I looked this up and if there is any error it appears to be related to it being audio-only. I think you may be confusion memory-mapped I/O with I/O _register_? I assume the difference would be the ability to work the registers directly without any memory accesses. User:Maury Markowitz

--Gavin86 00:12, 26 Dec 2004 (UTC) The 2A03 was used in the NES audio only. The modified 6502 CPU the NES used did not, as correctly stated, have a decimal mode. The NES Picture Processing Unit (PPU) is known as the 2C02. For reference: 2A03 (http://nesdev.parodius.com/2A03%20technical%20reference.txt) and 2C02 (http://nesdev.parodius.com/2C02%20technical%20reference.TXT)

6501<>6502 slot converters?

The fact that the processor only had a different pin arrangement than the 6501 makes me wonder if anyone made converters (much like the slockets that became common with Athlons and/or Pentiums of more recent times). Anyone know? —Mulad, May 29, 2003.

It wouldn't be too hard, except for the clocking stuff, which is different on the 6502. Simply get a 6800 datasheet (remember, the 6501 had the same pinout as the 6800), and a 6502 datasheet, and match the pins.

Clock multiplication

I think the 6502 was a static design and the comment about internal clock multiplcation is plain wrong. I had to write a grant application comparing processors mid 80's the real difference was that Z80 et. al. had clock dividers where the 6502 did not. I also have no knowledge of it ever doing 2 instructions at the same time. Archivist 23:57, Nov 13, 2003 (UTC) (For the application at the time, 6800 Z80 6802 6502 65C02(2Mhz), the 65C02 won hands down and was designed in.)

AFAIK the 6502 used a lot of dynamic logic, as was common in the NMOS days. It does not have a clock multiplier, but several phase shifted clocks that are internally generated. Check here for more information than you ever wanted to know http://impulzus.sch.bme.hu/6502/6502/6502_kapcs.php3 (oh wait, its hungarian..)
Btw, the Z80 did not have clock deviders, but a state machine. --Qdr 16:53, 13 Jul 2004 (UTC)

WDC's current line is now fully static, at least the 14mhz are from what I remember. --PZ

Terminator  6502 code

Thanks to Fixative for contributing the checksum program fact to the Trivia item on Terminator! Does someone by any chance have access to a copy of that exact code, either the complete program or the Terminator snippet? (yes, I plan to buy the DVD and press "still picture" at the magic moment, but I still think it strange that Google is unable to find me that code; also, since I was and am a Commodore man, I didn't read Nibble back in the day... come to think of it, Nibble probably never was available in Norway anyway). --Wernher 23:25, 22 Feb 2004 (UTC)

MOS Technology?

There is evidence that the company is not named "MOS Technologies", but rather "MOS Technology, inc.". See for example this datasheet: [1] (http://www.6502.org/archive/datasheets/mos_6581_sid.pdf). Anybody else has input on this? --Qdr 16:55, 13 Jul 2004 (UTC)

I'll have to check it in my databooks/sheets. I'd guess there's probably a reason the MOS articles started out under the "Technologies" name in the first place. --Wernher 21:34, 13 Jul 2004 (UTC)

I'm in the process of editing pages containing refrences to "MOS Technologies" to "MOS Technology", to give it it's proper name. This website has early MOS Technology, Inc. documents, dated January 1976. [2] (http://www.ping.be/kim-1__6502) It is a common mistake to refer to MOS as MOS Techonolgies. I for one made that mistake years ago. Saying "MOS Technologies" sounds right, where as saying "MOS Technology" sounds slightly awkward (for me at least). (Bill Bertram 00:16, 14 Jul 2004 (UTC))