我是一新手，在使用keil对一asm文件编译时出现如下信息：
Build target 'Target 1'
linking...
BL51 BANKED LINKER/LOCATER V5.03 - SN: Eval Version
COPYRIGHT KEIL ELEKTRONIK GmbH 1987 - 2002
"STARTUP.obj",
"51.obj"
TO "p89c58"
RAMSIZE(256)
*** WARNING L5: CODE SPACE MEMORY OVERLAP
   FROM:    0000H
   TO:      0002H
*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL
   SYMBOL:  ?C_START
   MODULE:  STARTUP.obj (?C_STARTUP)
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL
   SYMBOL:  ?C_START
   MODULE:  STARTUP.obj (?C_STARTUP)
   ADDRESS: 4587H
******************************************************************************
* RESTRICTED VERSION WITH 0800H BYTE CODE SIZE LIMIT; USED: 45C0H BYTE (871%) *
******************************************************************************
Program Size: data=9.0 xdata=0 code=17804
LINK/LOCATE RUN COMPLETE.  3 WARNING(S),  0 ERROR(S)
*** WARNING L5: CODE SPACE MEMORY OVERLAP
   FROM:    0000H
   TO:      0002H
*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL
   SYMBOL:  ?C_START
   MODULE:  STARTUP.obj (?C_STARTUP)
*** WARNING L2: REFERENCE MADE TO UNRESOLVED EXTERNAL
   SYMBOL:  ?C_START
   MODULE:  STARTUP.obj (?C_STARTUP)
   ADDRESS: 4587H
*** FATAL ERROR L250: CODE SIZE LIMIT IN RESTRICTED VERSION EXCEEDED
   MODULE:  STARTUP.obj (-----)
   LIMIT:   0800H BYTES
Target not created
请问上面的警告是什么意思？怎么解决？谢谢！！！