Re: high level on different 6502

From: didier derny <>
Date: Sun, 6 Nov 2016 08:14:24 +0100
Message-ID: <>
the measure was taken with an oscilloscope directly on the 6502,

for the loads they are the one normally on the bus

I've not added anything on the bus

On 06/11/2016 00:04, Segher Boessenkool wrote:
> On Sat, Nov 05, 2016 at 10:01:31PM +0100, Francesco Messineo wrote:
>> the High voltage at 2.5V isn't  a problem in itself (if it keeps the
>> level when loaded). TTL logic real "bad" noise margin is on the low
>> level (0.5V max output vs 0.8V max input).
>> So in theory 2.5V High should work as it has a still better noise
>> margin than the correct Low levels. Look also at the actual Low level
>> voltages on these parts however.
> The 6502 datasheet says output high is at least 2.4V.  The RIOT (6532)
> datasheet says input high is at least 2.4V.  If the outputs can only
> reach 2.5V then they will be slow ramping up to 2.4V, as well.
>> Then, one might wonder if Synertek parts were always marginal or they
>> didn't age well, but I can't surely tell :)
> Did you measure it with any (external) load?
> Segher
>         Message was sent through the cbm-hackers mailing list

       Message was sent through the cbm-hackers mailing list
Received on 2016-11-06 08:00:02

Archive generated by hypermail 2.2.0.