Reading the signature bytes of 87C51

[Mer_pri]

Hi,

I am trying to read the signature bytes of 87C51 according to the datasheet I will have to read 89H from address 30H and 58H from 31H. I have two set of chips with me. 

In one say A I am able to read out 89H and 57H but with another say B I read out 89H and 58H. I am not sure when A and B were purchased. 

Need some clarity on this. Not sure why same devices read out different signature bytes.

Thanks.

[Diego_INTEL]

Hello @Mer_pri,

Thank you for contacting Intel Embedded Community.

Unfortunately I don't have much information regarding this device as it is kind of old and not embedded.

Best regards,

@Diego_INTEL