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???
01/02/03 14:29
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#35411 - RE: P89C557E4
while (1}

{

P1 = 0

p1 = 1

}


This is what i have.



run it and put a scope on a p1 pin.



P1 is always HIGH (= +5V)



EA is connected to /PSEN by a 3k3 resistor, and seems to be +5V

EW is +5V (active low, thus disabled)




It Is NOT EA it is !EA, and thus it must be low to enable external program fetch.


external program should be disabled.
PSEN is +5V
EA is a square wave

EA is connected to PSEN via a 3k3 resistor, this is how i got the hardware.

!PSEN should pulse if the chip is running, put a scope on.



I did do that, and it displays a square wave



List of 15 messages in thread
TopicAuthorDate
P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      
RE: P89C557E4            01/01/70 00:00      

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