The base difference b/w S52 and C52 as Ian and Sawaak said is the S52 supports insustem programmin as C52 does not and there is another differce which i found was that whrn makin a programmer for C52 u will need a 12 V power supply where as for a programmer for S52 u just need 5 V power supply.
HI:
The 8051 structure of AT89c52 and AT89s52 are the same,but the type of flash
is different,for AT89c52:
VPP = 12V VPP = 5V
Top-side Mark AT89C52 AT89C52
xxxx xxxx - 5
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