MOS 6522 replacements - WDC W65C22N

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I want people to know I have used the N version of the W65C22 VIAs and I love'em. The manufacturer is Western Design Center aka WDC.

Usually, when you use CMOS versions of the 6522 chips, there is a problem with IRQ sharing since they use a totem pole output. The W65C22N fixes this problem and uses an open drain output.

The 2 main advantages to using a CMOS version of the VIAs is they use only a small fraction of the power of the original Commodore/MOS/CSG chips, usually less than 1/10th and, as a consequence, they don't heat at all.

I put a pair of the W65C22N in a 1541 drive along with a Rockwell R65C02 and it effectively turned it into a "no heat" drive.

The 6522 is used in the Commodore VIC-20 computer, some PET computers, the VIC-1540 disk drives, all 1541 drives and variants, the 1570 and 1571, the Emplant Macintosh emulator for Amiga computers and many early Macintosh computers.

Original 6522 chips also had a problem with their shift registers and this is fixed in the W65C22N.

The 2 units I bought were purchased from Mouser at 6.95$US each.

See:
http://www.westerndesigncenter.com/wdc/w65c22-chip.cfm

Just make sure you avoid the W65C22S if you want to be sure you get a direct drop-in replacement for old MOS 6522 chips.
 
This thread is what makes the C= / Amiga community great. Folks who go out and discover something, and share it for everyone's benefit. I wish the world was more like we are here. :) Thanks eslapion!

*picks up some chips for a rainy day*
 
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Well, when I first mentioned the W65C22N to other people, the first reply I got was that all CMOS versions of the 6522 cause problems with IRQ sharing. The N revision was specifically designed to resolve this problem so I thought I should let people know.
 
disco said:
Both Rockwell and WDC (except S) work fine. I've ordered some Rockwells after reading this (scroll to "Update", it is about half way down, this guy tested them all):
http://blog.tynemouthsoftware.co.uk/2015/11/vic20-penultimate-cartridge-part-1.html
Click to expand...

No, he absolutely did not test them all.

The Rockwell R6522 is okay but the Rockwell R65C22P or R65C22J are absolutely not okay; these are CMOS VIAs with a totem pole output on the IRQ and they will cause exactly the same problem as all other CMOS VIAs.

All Rockwell R65C22 do exactly the same thing as the W65C22S and should be avoided at all cost on 8 bit Commodore equipment.
 
I just bought a pack of 10 W65C22N in DIP 40 package so I thought it would be a good idea to revive this thread.

I thought of offering them along with GandALF as a form of 'Cool 1541' package since CMOS versions of the 6522 made by Western Design Center consume only 3mA of power while MOS 6522 ICs consume about 60mA (on the 5Vdc source). This represents a 20:1 reduction. No more heat!
 
I am saddened to read on various forums people have destroyed their VIC-20 or 1541 disk drives using the R65C22 or the W65C22S instead of the correct W65C22N.

Please let people know a substitute for the venerable old MOS 6522 is still available and in production. The W65C22N from Western Design Center is still in active production and is quite inexpensive.
 
Does anybody know a good source of W65C22N in Europe? Mouser charges 20€ for shipping, so it is only an option if buying in quantity.

Thanks!
 
eslapion said:
I am saddened to read on various forums people have destroyed their VIC-20 or 1541 disk drives using the R65C22 or the W65C22S instead of the correct W65C22N.
Click to expand...

Are you sure about the R65C22? Its datasheet states that IRQ is an open-collector drain output, contrary to the full output driver of the W65C22S.

Thanks!
 
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eduardocasino said:
Are you sure about the R65C22? Its datasheet states that IRQ is an open-collector drain output, contrary to the full output driver of the W65C22S.

Thanks!
Click to expand...
The Rockwell R65C22 had different varieties and which ones were open-drain and which ones were full totem-pole output was determined by a suffix letter. Since these are very old chips, I can't get the datasheet you found. You also did not post a link to the one you found.

I can only say for sure the W65C22N from Western Design Center (not to be mistaken with Western Digital) is still in production and is safe to use. The W65C22S is not unless you add a diode and the same is true for some R65C22 but I can't tell which ones. To be safe, I suggest you avoid them since you can only get old chips and lately China has been a champion at selling fakes of just about anything.
 
Thank you, I finally went by the safe way and purchased some W65C22N a few months ago, mainly because of what you also say about fakes from China.
 
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