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Posted By

gerliczer
on 2021-08-22
03:44:15
 Re: 7501 pinout

P5 is not routed to any pin. Zimmerman's collection has the Hardware Specification that also states that. The other two are incorrect.

Posted By

unclouded
on 2021-08-21
22:42:19
 7501 pinout

What's the correct pinout for the 7501? Different sources seem to disagree about whether the on-chip parallel port pins should be named P0 to P6 (consecutively) or P0 to P4 then P6 and P7 (P5 missing).

In the consecutive camp:
- [Wikipedia](https://commons.wikimedia.org/wiki/File:Mos_7501.png)
- [Zimmers](http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/plus4/manual/p4-07l.gif)

And in the gappy camp:
- [A MOS datasheet that seems to show a manual correction](https://myoldcomputer.nl/Files/mos_7501_8501.pdf)


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