Page 200 - Troubleshooting Analog Circuits

Appendix A

Digital ICs with Nonstandard Pinouts

I printed this little list of ICs that have nonstandard pinouts in EDN Magazine. back
in the fall of 1990, saying, “Tell me if this list is incorrect or incomplete,” but I have
not heard any complaints.
Example: The DM7486 and DM74S86 and DM74LS86 and MM74C386 all have
the same pinout. But the DM74L86 and MM74C86 have a different pinout. When the
L86 came out, it was not pin-compatible with the 7486, and of course the C86 came
out to be compatible with the L86. Several of these parts are rare and obsolescent
and sole-sourced, and you will probably never see one, but they are listed here for
completeness.
Here is the complete list:
74H01
74~51, Ls51
74H53

74L54, LS54, H54
74855
74L71
74L78, LS78A

74L85, C85
74L86,C86
74L95,C95
Readers might also want to be aware that the DM74107 (for example) is pulse-
triggered, but the 74LS 107 is edge-triggered, so in some cases they might not be
exactly interchangeable. There are other similar cases, which can be gleaned from the
fine print of the data sheets of digital ICs. Refer also to Chapter 10. pages 123-124.
for a discussion of other incompatibilities of digital ICs.

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