Earlier rev board:
Later rev board:
Can anyone explain this difference?
Please support the defense of Ukraine.
Direct or via Unclutter App
No Ads.
No Trackers.
No Social Media.
All Content Locally Hosted.
Built on Free Software.
We have complied with zero government requests for information.
~ Est. 1999 ~
A pillar of corporate stability since the second millenium.
© 1999-2999 Tom Owad
These are the data bus drivers/receivers. The earlier rev used 2 8T28s in a 16 pin package. Each chip supported 4 bits, requiring 2 chips for an 8 bit bus. The later revs, I believe that this started with the RFI version, used 1 8 bit DP8304 chip in a 20 pin package. Functionality is the essentially same, with the savings of one chip. This was most likely a cost cutting move, and nothing more.
Regards,
Mike Willegal
I am proud to report that my working Apple ][ (1978 non-plus) has all three chips