Re: 65C02S in place of 1541 6502

From: Jim Brain <brain_at_jbrain.com>
Date: Thu, 5 Dec 2019 19:20:37 -0600
Message-ID: <b98fbbaa-2a58-99cc-4c04-10dd4238d62e_at_jbrain.com>
On 12/5/2019 6:53 PM, laughton_at_cyg.net wrote:
>
> The pinout may be a problem.  Or not...  But here's the low-down.
>
>
> The W65C02 uses pin 36 to input the BE signal (Bus Enable). This needs 
> to be held high.
>
>
> Pin 5 is the MLB output -- Memory Lock.  But this pin was previously a 
> no-connect, so it's unlikely to cause trouble (unless the mobo PCB 
> does have a connection for some reason).
>
>
> Pin 1 is the VPB output.  This pin was previously VSS.
>
>
> I suggest all three pins be bent outward so they don't engage the 
> socket.  Then tie BE to pin 8 (VDD).
>
Did, and the unit works now.  I don't know if 5 bent out is needed, but 
safe ruled the day.

Thanks for the quick response.  Obviously, this ignores the reason as to 
why this person wants to do this (he has perfectly good ICs in the unit 
now), but it is good to know.

Jim


>
>  -- Jeff
>
>
>
>
> On 2019-12-05 19:37, Jim Brain wrote:
>
>> Someone noted to me today that they replaced their NMOS 6502 with a 
>> WDC CMOS 65C02S in a 1541, and the unit failed to boot.
>>
>> I have verified it also does not work.
>>
>> Before I go trying to determine why things are not working, anyone 
>> already know why and what needs to be done to address?
>>
>> Jim
>>
>> -- 
>> Jim Brain
>> brain_at_jbrain.com  
>> www.jbrain.com
>
>

-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2020-05-29 23:46:31

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