How to use upper 128byte of AT89S52. i.e. SFRs(80H to FFH) Address indirectly with KEIL C51 for general purpose which are not in use. They are directly addressable only as SFR.
according to datasheet: 1. The lower 128 bytes of RAM (00H to 7FH) are directly and indirectly addressable. 2. The higher 128 bytes of RAM (80H to FFH) are indirectly addressable. 3. The special function registers (80H to FFH) are directly addressable only.
Please help me thanks!
"Using a 16-bit loop counter for a loop over idata exposes a fundamental misunderstanding about the '51 architecture."
Oh jeez, come on! Even the most experienced of programmers can sometimes come up with quick test functions using code templates that may include 16 bit counters. Haven't you ever done that? I know I have - And I consider myself to have more than just a fundamental understanding of the '51 architecture.
"No loop over idata can ever, possibly, need a 16-bit loop counter."
It may not be needed, but where in the rule book does it say you must not do it?
Might as well extend your comment and say 7-bit ASCII should never be stored in a 16 bit variable - Clearly ludicrous.