The pushbutton reset with which I had the trouble with the HMOS parts was the one on the RC. The 1232 didn't work in either case with the MCU's that didn't work properly. Those same presumably defective MCU's reset O.K. on power-on, but the pushbutton reset, in either the case with the comparator and counters, or in the case with the RC, didn't reset at all when the reset pushbutton was used. Now, I did monitor the pulse width resulting from either action, and, while the pushbutton along with the RC was of whatever length the RC determined it would be, it didn't seem to matter.

It's rather annoying that these parts have problems with so simple a function. Other MCU's, 'HC11, 'HC05/08 have never exhibited such peculiarity. I used simple RC resets on 8048's without ever encountering a problem. Z80, 680x, 6502, etc, all happily tolerated RC reset without a cough. 1 nF and 10K-ohms was generally adequate, though one could use 0.1 nf, or 1 uF without a thought, whether the pullup was 1K or 50K.

I still think the parts are broken. The ones that work seem to work fine, and the ones that mess up always mess up.

RE