On Sat, Nov 5, 2016 at 9:37 PM, didier derny <didier@aida.org> wrote: > while checking some signals on the 6502 of my 8032 motherboard > I found the 'high' level rather low 2.5v (I expected around 4v...) > > so I took my SYM1 board and tested several 6502 > MOS 6502 around 4v > Rockwell 6502 around 4v > Rockwell 65c02 around 5v > Synertek 6502 around 2.5v > CM630 around 4v (bulgarian clone) > > I tried several 6502 of each type... 2.5V is really a bit outside the acceptable output High level for TTL logic. 2.7V is the official minimum level for the High state. However, TTL inputs should accept as High any voltage => 2V. If the current capability of the outputs isn't degraded (i.e. if 2.5V is maintained at all the inputs when loaded at the max fan-out), I'd say it should still work. CMOS outputs, on the other hand, should go to the power rails, if they aren't broken. Do you have many Synertek and they all have the same output levels? Frank Message was sent through the cbm-hackers mailing listReceived on 2016-11-05 21:00:30
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