Re: high level on different 6502

I only have 4 boards with a 6502

cbm 8032

SYM 1

MICRO KIM

REPLICA 1


same result on cbm and sym, I'll try on the micro kim and replica 1

note: the replica 1 has an instability and crash often  (seems due to 
the propeller)

I'll try on these 2 boards



On 06/11/2016 15:13, Gerrit Heitsch wrote:
> On 11/05/2016 09:37 PM, didier derny 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...
>
> Since I was curious and able to test it... A few years ago I built 
> myself a replica of the EMUF232 on a perfboard (was a real pain in 
> the...). That's a 6502 system with 2 x 6522, 1 6551, 32KB RAM running 
> at 1.8432 MHz. As a CPU I used a SY6502A, datecode 8047.
>
> When checking the address lines on the scope today, the CPU produces a 
> HIGH of 3.5-3.7V. So it can't be Synertek in general unless the 
> drivers are less powerful than Rockwell and MOS and your board has 
> more load on the lines. If possible, check the SY6502 in another 
> board, maybe a 1541.
>
>  Gerrit
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