That's probably my problem

CMOS logic will have no problem driving 28C256. When you removed the EEPROM from the circuit, it was eliminated from being a problem.

 

That's probably my problem

not likely.

here is the code I showed earlier performing in simulation.



the code is:

        eprom_write(0x5522);                //send test value 1
        delay(100);                            //waste some time
        eprom_write(0x2255);                //send test value 2
        delay(200);                            //waste some time

the first value being sent is 0x5522, and then 0x2255. You can compare those values with the output on the shift registers.

 

not likely.

here is the code I showed earlier performing in simulation.

View attachment 118715

the code is:

        eprom_write(0x5522);                //send test value 1
        delay(100);                            //waste some time
        eprom_write(0x2255);                //send test value 2
        delay(200);                            //waste some time

the first value being sent is 0x5522, and then 0x2255. You can compare those values with the output on the shift registers.

The reason why I believe the HCT is the answer is because my EEPROM might require more current on its inputs to run properly and the HC version wouldn't provide enough current. I think its worth switching since HCT provides 5x more current compared to HC according to that link I showed

 

The reason why I believe the HCT is the answer is because my EEPROM might require more current on its inputs to run properly and the HC version wouldn't provide enough current.

AT28C256 input current is 10uA max. You already established that the EEPROM wasn't the problem when you removed it from the circuit.

 

Have I missed somthing or it the OP still trying to make it work without fixing the power supply problem ?

Les.

 

Have I missed somthing or it the OP still trying to make it work without fixing the power supply problem ?

Still throwing things at the wall and hoping something will stick...