Re: 6522 VIA inputs

From: Gerrit Heitsch <>
Date: Sat, 22 Apr 2017 22:53:44 +0200
Message-ID: <>
On 04/22/2017 10:48 PM, smf wrote:
> On 22/04/2017 21:45, Gerrit Heitsch wrote:
>> You might overload the NMOS driver if the CMOS driver can supply more
>> current than the NMOS driver can sink. Over time that could cause damage.
> So it would depend on the CMOS output current? Would a current limiting
> resistor help?

Sure, if you limit the current to below what the NMOS driver can sink. 
Such a resistor will affect rise and fall times though.

On example where people overloaded an NMOS driver were the external 16KB 
memory expansions for the C16/C116. You cannot disable the internal RAM 
on these systems in a clean way from a card in the expansion port. What 
you CAN do is to brute force /CAS to HIGH. Of course, that will overload 
the output driver in TED.


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Received on 2017-04-22 21:01:46

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