There is a Tech Note or disscusion archive on the Tarnover site that talks about replacing two 74LS chips with 74F to correct a timing issue between the 6502 and 65c02 on a II+. It had an indepth review of the effected circuits. Kevin On Sun, 24 Jun 2001 12:31:59 -0400, "Tom Zuchowski" wrote: >I don't have personal experience in doing a 6502/65C02 swap, but I do >industrial digital electronics repair for a living and I have never heard of >a case where you could not swap the "standard" NMOS version of a VLSI chip >with the CMOS version. There are no doubt a few instances of such >compatibilities, but I assure you that they are very rare, and they will be >very narrow in their scope. On the whole, the biggest differences to the >user between NMOS and CMOS IC's is that the CMOS version consumes far less >power and it is generally able to utilize a larger scope of supply voltages. > >I can't imagine ANY way in which a 65C02 could damage a II+ motherboard. As >for the ROMs/EPROMS, they are virtually 100% interchangeable electronically, >though the CMOS versions consume a LOT less power. The timing requirements >are a little different and the 65C02 may not work, but it can't possibly >damage the motherboard. Let's remember that any time you mess with a >motherboard you are running a risk of damage, especially on our old, old >Apple II stuff. I can probably come up with a half-dozen different things >that might have killed Cliff's II+, but I don't think it had anything to do >with electronic incompatibility with the 65C02. > >Tom Zuchowski > > >"Stephen Shaw" wrote in message >news:9h51ft$39s$1@venus.itns.co.za... >> Very doubtful that the 65C02 caused the II+ to die. >> >> On Fri, 08 Jun 2001 16:51:22 +1000, John L wrote: >> >> > On Thu, 07 Jun 2001 22:37:19 -0700, Cliff Allo >> > wrote: >> > >> >>Because the 65C02 may have a different resistance or voltage >> >>requirement from the stock 6502, you risk burning your ROMs if you >> >>simply swap the CPUs. At least that's how I killed my ][+. >> > >> > >> > Can anyone here confirm or deny this ? >> > >> > I have a ][+ running with a 65c02 - no apparent problems. >> >> -- >> The reason computer chips are so small is computers don't eat so much. > It is located in the Apple Assembly Line Archives. The file A2.AAL.ARCHIVES.INFO.txt is an index to the BXY disks. 8412, 8503 and 8509 have the most info on the 65c02 in a II+ http://tarnover.dyndns.org/Pubs/Apple.Assembly.Line.Archives/ Also, there used to be a filed called aal.zip in this directory. It had all the text files already extracted. The zip file is gone. Somebody should convert the .BXY disks to .DSK disks so we can read the text files on an emulator. On Tue, 26 Jun 2001 13:23:48 +1000, John L wrote: >On Mon, 25 Jun 2001 15:04:41 -0400, agentwd40 >wrote: > >>There is a Tech Note or disscusion archive on the Tarnover site that >>talks about replacing two 74LS chips with 74F to correct a timing >>issue between the 6502 and 65c02 on a II+. It had an indepth review of >>the effected circuits. > >Is this technote/discussion in the "FAQ and Info" directory on >Tarnover ? > >What name does it come under ? > > > >