Hi the 65c02 high level was near VCC I had 2 Synertek 6502 both were at 2.5v for the high level... 2 differents machines SYM1 and CBM8032, same results... looks like the problem is linked to the synertek On 05/11/2016 21:50, Francesco Messineo wrote: > On Sat, Nov 5, 2016 at 9:37 PM, didier derny <email@example.com> 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 list Message was sent through the cbm-hackers mailing listReceived on 2016-11-05 21:00:45
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