用汇编？？这一句我也不知道什么意思，不过建议用KEIL C，从AVR转向51很简单

我和你相反，用了一年半51单片机，我也开始玩AVR，现在公司一直用AVR的单片机，原来我一直用STC的单片机。

NOMOD51
Abbreviation: NOMO
Arguments:    None.
Default:      The A51 assembler pre-defines all special function registersof the 8051 CPU. The A251 assembler and
              the  AX51assembler do not pre-define any CPU special functionregisters.
Control Class:Primary
μVision2 Control: Options – Ax51 – Special Function Registers – Define 8051 SFR Names.
Description:  The NOMOD51 control prevents the A51 assembler from implicitly defining symbols for the default 8051  special function registers. This is necessary when you want to
include a definition file to declare symbols for the s

请看keilc下的帮助文件KeilC51HLPA51.pdf。

哦.谢谢 afeibfp 的帮助.

和LZ的经历相差不多，现在也是STC 51，也在弄汇编