ARM Technical Support Knowledge Articles

80C517A MA-STEP SHIFT BUG

Applies to: C51 C Compiler

Answer

QUESTION

I've heard there is a bug in the MA version of the 517A. If the 4 bit shift instruction (right or left) is used, one must wait 1 machine cycle before reading the result. I assume a simple NOP will suffice. Does the Keil toolset for the 8051 take this into consideration?

ANSWER

Yes. The C51 Library takes care of that. There is no need to modify anything in your program for this to work correctly.

Article last edited on: 2004-05-16 17:43:28

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